Chapter 2 Atoms, Molecules, and Ions James F. Kirby Quinnipiac University Hamden, CT Lecture Presentation © 2015 Pearson Education, Inc.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Atomic Theory of Matter The theory that atoms are the fundamental building blocks of matter reemerged in the early nineteenth century, championed by John Dalton.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Dalton’s Postulates 1)Each element is composed of extremely small particles called atoms.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Dalton’s Postulates 2)All atoms of a given element are identical to one another in mass and other properties, but the atoms of one element are different from the atoms of all other elements.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Dalton’s Postulates 3)Atoms of an element are not changed into atoms of a different element by chemical reactions; atoms are neither created nor destroyed in chemical reactions.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Law of Conservation of Mass  The total mass of substances present at the end of a chemical process is the same as the mass of substances present before the process took place.  This law was one of the laws on which Dalton’s atomic theory was based.  Lavoisier

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Dalton’s Postulates 4)Atoms of more than one element combine to form compounds; a given compound always has the same relative number and kind of atoms.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. My fourt posulate is an extension of a law formulated by the French chemist, Joseph Proust ( ), in Proust’s Law of Definite Proportions states: Different samples of the same compound always contain its con- stituent elements in the same proportion by mass. If we analyzed any number of samples of sodium chloride, NaCl, collected from different sources, we would find in each and every sample the same ratio BY MASS of sodium (Na) to chlorine (Cl). Thus, if the ratio of the MASSES of different elements in a compound is fixed, the ratio of the ATOMS of these elements in the compound must also be constant.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Law of Multiple Proportions  If two elements, A and B, form more than one compound, the masses of B that combine with a given mass of A are in the ratio of small whole numbers.  Dalton predicted this law and observed it while developing his atomic theory.  When two or more compounds exist from the same elements, they can not have the same relative number of atoms.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Discovery of Subatomic Particles In Dalton’s view, the atom was the smallest particle possible. Many discoveries led to the fact that the atom itself was made up of smaller particles.  Electrons and cathode rays  Radioactivity  Nucleus, protons, and neutrons

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. ATOMIC STRUCTURE Dalton thought of atoms as being indivisible and, thus, extremely small. Millikan Thomson Rutherford Becquerel A series of investigations that began in the 1850s and extended into the 20th century demonstrated clearly that atoms themselves had internal structure; i.e., atoms are made up of even smaller particles!!. SAY IT ISN’T SO!!! WHAT ARE THEY?

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. The Electron (Cathode Rays) Streams of negatively charged particles were found to emanate from cathode tubes, causing fluorescence. J. J. Thomson is credited with their discovery (1897).

© 2015 Pearson Education, Inc. How do we deduce from the figure that cathode rays travel from cathode to anode? a.The cathode and anode are labeled in figure (a). b.A green gas exists in the vacuum tube. c.Cathode rays consist of charge particles. d.the manner in which the magnet diverts the path in figure (b)

© 2015 Pearson Education, Inc. How do we deduce from the figure that cathode rays travel from cathode to anode? a.The cathode and anode are labeled in figure (a). b.A green gas exists in the vacuum tube. c.Cathode rays consist of charge particles. d.the manner in which the magnet diverts the path in figure (b)

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. High Voltage - + Cathode Anode Fluorescent screen A B In the absence of an electric field, electrons emitted by the cathode are drawn to the anode, pass through the hole in the anode center, and strike the fluorescent screen at point A. In the presence of an external electric field, electrons emitted by the cathode eventually strike the fluorescent screen at point B. This is due to the negatively charged electrons being deflected by the negative part of the electric field and attracted toward the positive part of the field. See Textbook page 30 Cathode ray tube

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. The Electron Thomson measured the charge/mass ratio of the electron to be 1.76  10 8 coulombs/gram (C/g).

© 2015 Pearson Education, Inc. If no magnetic field were applied, would you expect the electron beam to be deflected upward or downward by the electric field? a.Downward because a negative particle is repelled by a negative plate and attracted to a positive plate. b.Upward because a negative particle is attracted to a negative plate and repelled by a positive plate. c.Downward because a negative particle is attracted to a negative plate and repelled by a positive plate. d.Upward because a negative particle is repelled by a negative plate and attracted to a positive plate.

© 2015 Pearson Education, Inc. If no magnetic field were applied, would you expect the electron beam to be deflected upward or downward by the electric field? a.Downward because a negative particle is repelled by a negative plate and attracted to a positive plate. b.Upward because a negative particle is attracted to a negative plate and repelled by a positive plate. c.Downward because a negative particle is attracted to a negative plate and repelled by a positive plate. d.Upward because a negative particle is repelled by a negative plate and attracted to a positive plate.

© 2015 Pearson Education, Inc. Using a cathode ray tube and his extensive knowledge of electromagnetic theory, Thomson determined the ratio of electric charge to mass for an electron x 10 8 coulombs/gram The coulomb (C) is a unit of electric charge. R. A. Millikan successfully measured the charge on, and mass of, an individual electron by studying the motion of single tiny oil drops that acquired charge from ions in the air x g (mass of an individual electron) Incredibly small charge and mass!! x C (charge on an individual electron)

© 2015 Pearson Education, Inc. QUICK TIME VIDEO

© 2015 Pearson Education, Inc. Robert Millikan’s (in)famous “Oil Drop” Experiment ++ - charged plate atomize r viewing microscop e oil droplets under observatio n oil droplets charge x C mass of electron = = = 9.10 x g charge/mass x 10 8 C/g (Based on Fig. 2.5, p. 39, Chang 7th ed.) small hole

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Millikan Oil-Drop Experiment (Electrons)  Once the charge/mass ratio of the electron was known, determination of either the charge or the mass of an electron would yield the other.  Robert Millikan determined the charge on the electron in 1909.

© 2015 Pearson Education, Inc. Would the masses of the oil drops be changed significantly by any electrons that accumulate on them? a.Yes, the electrons add significant mass to the oil drop. b.No, the electrons add only a small mass to the oil drop. c.Yes, the electrons cause the oil drops to stick together.

© 2015 Pearson Education, Inc. Would the masses of the oil drops be changed significantly by any electrons that accumulate on them? a.Yes, the electrons add significant mass to the oil drop. b.No, the electrons add only a small mass to the oil drop. c.Yes, the electrons cause the oil drops to stick together.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Radioactivity Radioactivity is the spontaneous emission of high-energy radiation by an atom. It was first observed by Henri Becquerel. Marie and Pierre Curie also studied it. Its discovery showed that the atom had more subatomic particles and energy associated with it.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Radioactivity Three types of radiation were discovered by Ernest Rutherford: –  particles (positively charged) –  particles (negatively charged, like electrons) –  rays (uncharged)

© 2015 Pearson Education, Inc. (1) Which of the three kinds of radiation shown consists of electrons? (1) a.β b.γ c.α d. (A) and (C)

© 2015 Pearson Education, Inc. (1) Which of the three kinds of radiation shown consists of electrons? (1) a.β b.γ c.α d. (A) and (C)

© 2015 Pearson Education, Inc. (2) Why are these rays deflected to a greater extent than the others? (2) a.Beta particles are negatively charged. b.Alpha particles are positively charged. c.Alpha particles are less massive than beta particles. d.Beta particles are less massive than alpha particles.

© 2015 Pearson Education, Inc. (2) Why are these rays deflected to a greater extent than the others? (2) a.Beta particles are negatively charged. b.Alpha particles are positively charged. c.Alpha particles are less massive than beta particles. d.Beta particles are less massive than alpha particles.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. The Atom, circa 1900 The prevailing theory was that of the “plum pudding” model, put forward by Thomson. It featured a positive sphere of matter with negative electrons embedded in it.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Discovery of the Nucleus Ernest Rutherford shot  particles at a thin sheet of gold foil and observed the pattern of scatter of the particles.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. E. Rutherford ( ) Structure of the Atom: The Proton & Nucleus Rutherford’s experiment for measuring scattering of  particles by a thin metal foil: Rutherford used  particles to probe atomic structure. Thin gold and other metal foils served as targets for  particles. See the illustration below (from S. Zumdahl slides). Most of the  particles penetrated the metal foils with little or no deflection. However, an  particle would be deflected at a large angle or back toward the source!   

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. 1.atoms positive charge is concentrated in the nucleus 2.proton (p) has opposite (+) charge of electron 3.mass of p is 1840 x mass of e - (1.67 x g)  particle velocity ~ 1.4 x 10 7 m/s (~5% speed of light) (1908 Nobel Prize in Chemistry) QUICK TIME VIDEO

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Structure of the Atom: The Proton & Nucleus E. Rutherford ( ) Rutherford formulated his model of the atom, based on the results of his  -scattering experiments:     Mostly empty space, which would explain why most  particles passed through the foil undetected. Atom’s positive charges concentrated in the nucleus, a dense central core within the atom. This would explain why those  particles that came near or directly at the nucleus experienced large deflections or reversed directions (repulsion of positive charge by positive charge). We now know these positively charged particles in the nucleus as protons: Mass of proton = x g -- about 1840x the mass of an electron. Typical atomic radius is about 100 pm (pm = picometers). Radius of atomic nucleus ONLY about 5 x pm !!! IT’S LIKE PLACING A MARBLE IN THE MIDDLE OF THE HOUSTON ASTRODOME!!!

© 2015 Pearson Education, Inc. What is the charge on the particles that form the beam? a.–1, because the beam consists of beta particles. b.+2, because the beam consists of alpha particles. c.+1, because the beam consists of beta particles. d.–2, because the beam consists of alpha particles.

© 2015 Pearson Education, Inc. What is the charge on the particles that form the beam? a.–1, because the beam consists of beta particles. b.+2, because the beam consists of alpha particles. c.+1, because the beam consists of beta particles. d.–2, because the beam consists of alpha particles.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. The Nuclear Atom Since some particles were deflected at large angles, Thomson’s model could not be correct.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. The Nuclear Atom Rutherford postulated a very small, dense nucleus with the electrons around the outside of the atom. Most of the volume is empty space. Atoms are very small; 1 – 5 Å or 100 – 500 pm. Other subatomic particles (protons and neutrons) were discovered.

© 2015 Pearson Education, Inc. What is the approximate diameter of the nucleus in units of pm? a.100 pm b.1 pm c.10 –2 pm d.10 –4 pm

© 2015 Pearson Education, Inc. What is the approximate diameter of the nucleus in units of pm? a.100 pm b.1 pm c.10 –2 pm d.10 –4 pm

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Structure of the Atom: The Neutron Rutherford’s model of the atom left one question unanswered: Why is the ratio of the mass of the He atom to that of the H atom actually 4:1 instead of the 2:1 ratio predicted by Rutherford’s model? - We electrons have very little mass compared to protons! Thus, our contribution to atomic mass is negligible!!

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Structure of the Atom: The Neutron A number of my colleagues and I postulated that another type of subatomic particle exists in the atomic nucleus. Lord Ernest Rutherford Sir James Chadwick ( ) My coworkers and I carried out the bombardment of Be (beryllium) metal with  particles. We observed that the Be gave off high-energy radiation that we found was unaffected by electric fields or magnets. 

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Structure of the Atom: The Neutron I gave the name neutrons to the subatomic particles that comprised the high-energy radiation given off by the Be metal. A neutron is an electrically neutral particle with a mass of x g -- just slightly larger than the mass of the positive proton ( x g). e-e- e-e- e-e- proton (p) neutron (n) p p n H He relative mass = 1 relative mass = 4

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Subatomic Particles Protons (+1) and electrons (–1) have a charge; neutrons are neutral. Protons and neutrons have essentially the same mass (relative mass 1). The mass of an electron is so small we ignore it (relative mass 0). Protons and neutrons are found in the nucleus; electrons travel around the nucleus.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Atomic Mass Atoms have extremely small masses. The heaviest known atoms have a mass of approximately 4 × 10 –22 g. A mass scale on the atomic level is used, where an atomic mass unit (amu) is the base unit.  1 amu = × 10 –24 g

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Atomic Weight Measurement Atomic and molecular weight can be measured with great accuracy using a mass spectrometer. Masses of atoms are compared to the carbon atom with 6 protons and 6 neutrons (C-12).

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Symbols of Elements  Elements are represented by a one or two letter symbol. This is the symbol for carbon.  All atoms of the same element have the same number of protons, which is called the atomic number, Z. It is written as a subscript BEFORE the symbol.  The mass number is the total number of protons and neutrons in the nucleus of an atom. It is written as a superscript BEFORE the symbol.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Isotopes Isotopes are atoms of the same element with different masses. Isotopes have different numbers of neutrons, but the same number of protons.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. 8 O 16 ATOMIC NUMBER (Z) The number of protons in the nucleus of an atom of each element In a neutral atom: # of protons = # of electrons The element considered above is oxygen. How many protons does a neutral oxygen atom contain? How many electrons? Where are the protons located in the oxygen atom?

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. 8 O 16 ATOMIC MASS The total number of protons + neutrons in the nucleus of an atom of each element In a neutral atom: mass number = # of protons + # of neutrons A = Z + # neutrons Where are neutrons located? What is their charge? Mass Number (A)

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Isotopes Atoms that have the same atomic number but different mass numbers 1 H 1 2 H 1 3 H 1 3 Isotopes of Hydrogen hydrogendeuteriumtritium mass number = A atomic number = Z A X Z element symbol The accepted format for writing an isotope 1 proton 0 neutrons 1 proton 1 neutron 1 proton 2 neutrons

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Atomic number (Z) = number of protons in nucleus Mass number (A) = number of protons + number of neutrons = atomic number (Z) + number of neutrons Isotopes are atoms of the same element (X) with different numbers of neutrons in the nucleus X A Z H 1 1 H (D) 2 1 H (T) 3 1 U U Mass Number Atomic Number Element Symbol Or it can be written as X—A ex) Sr-90

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Try these isotopes! Determine: (a) no. of protons; (b) no. of neutrons; (c) no. of electrons. 235 U U Fe Th Cu I 53

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. How many protons, neutrons, and electrons are in C 14 6 ? How many protons, neutrons, and electrons are in C 11 6 ? Do You Understand Isotopes?

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Hwk: page 73-79: 12, 17, 21, 23, 26, 27, 28, 31, 92

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. LESSON 2

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Atomic Weight Because in the real world we use large amounts of atoms and molecules, we use average masses in calculations. An average mass is found using all isotopes of an element weighted by their relative abundances. This is the element’s atomic weight. That is, Atomic Weight = Ʃ [(isotope mass) × (fractional natural abundance)]. Note: the sum is for ALL isotopes of an element.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. An average carbon atom consists chiefly of 2 isotopes: 12 6 C 13 6 C 98.9% abundant; amu 1.1% abundant; amu

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc C 13 6 C 98.9% abundant; amu 1.1% abundant; amu Avg. atomic mass of C = (0.9890)(12.00 amu) + (0.0110)( amu) amu

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Avg. Atomic Mass = ( )( mass in amu ) +···

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Natural lithium is: 7.42% 6 Li (6.015 amu) 92.58% 7 Li (7.016 amu) 7.42 x x = amu Average atomic mass of lithium:

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Atomic masses of elements are indeed average masses: 1 H atom = amu 1 O atom = amu 1 Fe atom = amu …based on elements’ isotopes and their abundances

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Periodic Table The periodic table is a systematic organization of the elements. Elements are arranged in order of atomic number. Unlike the way we write isotopes, the atomic number is at the TOP of a box in the periodic table. The atomic weight of an element appears at the BOTTOM of the box. (They are not shown on this version of the Periodic Table.)

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Periodic Table The rows on the periodic table are called periods. Columns are called groups. Elements in the same group have similar chemical properties.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Periodicity When one looks at the chemical properties of elements, one notices a repeating pattern of reactivities.

© 2015 Pearson Education, Inc. If F is a reactive nonmetal, which other element or elements shown here do you expect to also be a reactive nonmetal? a.He and Ar b.Be and Ca c.H and Cl d.Ne and Ar

© 2015 Pearson Education, Inc. If F is a reactive nonmetal, which other element or elements shown here do you expect to also be a reactive nonmetal? a.He and Ar b.Be and Ca c.H and Cl d.Ne and Ar

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Intro. to the Periodic Table Movie

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. PERIODIC TABLE of the ELEMENTS Elements 104 through 109 have been named (Rf, Db, Sg, Bh, Hs, Mt). Based on repeating trends in chemical & physical properties of elements... Developed in 1869 by Dmitri Mendeleev, a Russian chemist….

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. 104 Rf Db Sg Bh Hs (265) 109 Mt (266) Elements 104 through 109 now have names... Rutherfordium (named for Lord Rutherford) Dubnium (named for the Dubna nuclear research facility in Russia Seaborgium (named for Glenn T. Seaborg) Bohrium (named for Niels Bohr) Hassium (named for Hassen state in Germany) Meitnerium (named for Lise Meitner)

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. GROUPS: (a.k.a. FAMILIES) OF ELEMENTS 1. Vertical arrangements of elements 2. Possess similar chemical & physical properties

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. GROUP 1 ELEMENTS (IA) ALKALI (AL-kuh-lie) metals Hydroge n (HI-dro- jen) Lithium (LITH-ee- um) Sodium (SO-dee- um) Potassium (po-TASS-ee- um) Rubidium (roo-BID-ee- um) Cesium (SEE-zee-um) Francium (FRAN-see- um)

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. GROUP 2 ELEMENTS (IIA) ALKALINE EARTH (AL-kuh-lin URTH) metals Beryllium (bur-RILL-ee- um) Magnesium (mag-NEE-zee- um) Calcium (CAL-see- um) Strontium (STRON-tee- um) Barium (BEAR-ee- um) Radium (RAY-dee-um)

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. GROUP 16 ELEMENTS (VIA) CHALCOGENS (CHALL-ko-jens) Oxygen (OX-ee- jen) Sulfur (SULL-fur) Selenium (sel-LEAN-ee- um) Tellurium (tell-LURE-ee- um) Polonium (po-LOW-nee- um)

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. GROUP 17 ELEMENTS (VIIA) HALOGENS (HAL-low-jens) Fluorine (FLOOR- een) Chlorine (KLOR-een) Iodine (EYE-oh-deen) Bromine (BRO-meen) Astatine (ASS-tuh-teen)

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. GROUP 18 ELEMENTS (VIIIA) NOBLE (or INERT) GASES Helium (HEE-lee- um) Neon (NEE-on) Argon (ARE-gone) Krypton (KRIP-tawn) Xenon (ZEE-non) Radon (RAY-dawn)

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. PERIODS: (or ROWS) OF ELEMENTS 1. Horizontal arrangements of elements 2. Possess common characteristics

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Main Group Elementsgroups 1, 2, 13  18 Representative Elements

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Transition elements = groups 3  12

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. The Lanthanide and Actinide series are also known as the Rare Earth Elements or Inner transition Elements

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Metals: Good conductors of heat and electricity; malleable; ductile; lustrous Nonmetals: Poor conductors of heat and electricity; hard Metalloids or Semi-Metals: Properties intermediate between those of metals and nonmetals In chemistry, all elements, natural & man-made, are grouped into one of three broad classifications:

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Periodic Table Metals are on the left side of the periodic table. Some properties of metals include  shiny luster.  conducting heat and electricity.  solidity (except mercury).

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Periodic Table Nonmetals are on the right side of the periodic table (with the exception of H). They can be solid (like carbon), liquid (like bromine), or gas (like neon) at room temperature.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Periodic Table Elements on the steplike line are metalloids (except Al, Po, and At). Their properties are sometimes like metals and sometimes like nonmetals.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Hwk: page 73-79: 35, 41, 43, 95, 96, 100

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. LESSON 3

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Chemical Formulas H 2 O (water) Those who do chemistry for a living use CHEMICAL FORMULAS to express composition of molecules and salts (i.e., ionic compounds) in terms of chemical symbols that represent the elements. Composition: Which elements are present--hydrogen (H) & oxygen (O) Composition: Combining ratios of the elements involved -- 2 hydrogens : 1 oxygen 2 H : 1 O

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Chemical Formulas The subscript to the right of the symbol of an element tells the number of atoms of that element in one molecule of the compound. Molecular compounds are composed of molecules and almost always contain only nonmetals.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Diatomic Molecules These seven elements occur naturally as molecules containing two atoms: –Hydrogen –Nitrogen –Oxygen –Fluorine –Chlorine –Bromine –Iodine

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Types of Formulas Empirical formulas give the lowest whole- number ratio of atoms of each element in a compound. Molecular formulas give the exact number of atoms of each element in a compound. If we know the molecular formula of a compound, we can determine its empirical formula. The converse is not true!

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. CHEMICAL FORMULAS 2 types MOLECULAR Exact no. of atoms of each element in smallest unit of substance EMPIRICAL Elements present in simplest whole-number ratio of their atoms C 6 H 12 O 6 glucoseCH 2 O

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. A molecular formula shows the exact number of atoms of each element in the smallest unit of a substance An empirical formula shows the simplest whole-number ratio of the atoms in a substance H2OH2O H2OH2O molecularempirical C 6 H 12 O 6 CH 2 O O3O3 O N2H4N2H4 NH 2 2.6

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. EMPIRICAL formulas The simplest chemical formulas Tell us which elements are present and simplest whole-number ratio of their atoms NOT NECESSARILY the actual number of atoms in a given molecule CH 2 O empirical formula C2H4O2C2H4O2 C3H6O3C3H6O3 C 6 H 12 O 6 molecular formulas Subscript “1” is understood & not written when there’s only ONE atom of an element present.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. MOLECULAR formulas Exact number of atoms of each element in the smallest unit of a substance O2O2 O3O3 H2OH2O H2H2 water ozone oxygen hydrogen Allotropes 2 or more distinct forms of an element

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Allotropes Carbon FullerenesGraphiteDiamond

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. H2OH2O NH 3 CO 2 CH 4 water ammonia carbon dioxide methane For these molecules, and many more, the empirical AND molecular formulas are the same.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Types of Formulas Structural formulas show the order in which atoms are attached. They do NOT depict the three-dimensional shape of molecules. Perspective drawings also show the three-dimensional order of the atoms in a compound. These are also demonstrated using models.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Chemical Formulas and Molecular Models OR “How Do We Visualize Something as Ridiculously Small as a Molecule?” USE MOLECULAR MODELS!!! CHH H H CH 4 C H H H H Molecular formula Structural formula Ball-and-stick model Space-filling model

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. 2.6

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc.

Which model, the ball-and-stick or the space- filling, more effectively shows the angles between bonds around a central atom? a.Ball-and-stick b.Space-filling

© 2015 Pearson Education, Inc. Which model, the ball-and-stick or the space- filling, more effectively shows the angles between bonds around a central atom? a.Ball-and-stick b.Space-filling

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Ions When an atom of a group of atoms loses or gains electrons, it becomes an ion. Cations are formed when at least one electron is lost. Monatomic cations are formed by metals. Anions are formed when at least one electron is gained. Monatomic anions are formed by nonmetals.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Ions An atom or group of atoms having a net positive or negative charge. Two types of ions... CATIONS Ions with a net positive charge. Formed by LOSS of one or more electrons from a neutral atom. ANIONS Ions with a net negative charge. Formed by GAIN of one or more electrons by a neutral atom. Monatomic ions: have only 1 atom Polyatomic ions: more than 1 atom

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. A monatomic ion contains only one atom A polyatomic ion contains more than one atom 2.5 Na +, Cl -, Ca 2+, O 2-, Al 3+, N 3- OH -, CN -, NH 4 +, NO 3 -

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Ions Na Na + CATION Cl Cl - ANION Na + + Cl - Na + Cl - IONIC COMPOUND Formed from cations and anions Sodium ion Chloride ion Sodium chloride -1e - +1e -

© 2015 Pearson Education, Inc. (1) The most common ions for silver, zinc, and scandium are Ag +, Zn 2+, and Sc 3+. Locate the boxes in which you would place these ions in this table. (1) Ag + Zn 2+ Sc 3+ a.2B3B4B b. 1B2B3B c.1B3B2B d.4B3B2B

© 2015 Pearson Education, Inc. (1) The most common ions for silver, zinc, and scandium are Ag +, Zn 2+, and Sc 3+. Locate the boxes in which you would place these ions in this table. (1) Ag + Zn 2+ Sc 3+ a.2B3B4B b. 1B2B3B c.1B3B2B d.4B3B2B

© 2015 Pearson Education, Inc. (2) Which of these ions have the same number of electrons as a noble gas element? (2) a.Ag + b.Zn 2+ c.Sc 3+ d.(B) and (C)

© 2015 Pearson Education, Inc. (2) Which of these ions have the same number of electrons as a noble gas element? (2) a.Ag + b.Zn 2+ c.Sc 3+ d.(B) and (C)

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Common Cations

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Common Anions

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Examples of Ions ** Monatomic Cations Li + lithium ion Na + sodium ion Mg 2+ magnesium ion Ba 2+ barium ion Cr 3+ chromium (III) ion* Cr 6+ chromium (VI) ion* Fe 2+ iron (II) ion* Fe 3+ iron (III) ion* Al 3+ aluminum ion Pb 2+ lead (II) ion* Pb 4+ lead (IV) ion* * For cations with more than one charge possible, a Roman numeral is used to denote the charge on the cation. Monatomic Anions F - fluoride ion Cl - chloride ion Br - bromide ion I - iodide ion O 2- oxide ion S 2- sulfide ion N 3- nitride ion P 3- phosphide ion C 4- carbide ion Polyatomic Ions NH 4 + ammonium ion PO 4 3- phosphate ion SO 4 2- sulfate ion CO 3 2- carbonate ion NO 3 - nitrate ion C 2 H 3 O 2 - acetate ion OH - hydroxide ion CN - cyanide ion ** Refer also to Figure 2.11, p. 49, Chang 7th ed.)

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Hydride H - Hydrogen H + Cesium Cs + Rubidium Rb + Barium Ba 2+ Strontium Sr 2+ Potassium K + Calcium Ca 2+ Lithium Li + Beryllium Be 2+ Sodium Na + Magnesium Mg 2+ Aluminum Al 3+ Carbide C 4- Phosphide P 3- Nitride N 3- Telluride Te 2- Selenide Se 2- Sulfide S 2- Oxide O 2- Iodide I - Bromide Br - Chloride Cl - Fluoride F - MONOATOMIC IONS CATIONSANIONS Hydrogen can be both a cation and an anion.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Metal Ion Cr 2+ Stock Name chromium (II)manganese (II) manganese (IV) copper (II) tin (II) tin (IV) manganese (III) manganese (VI) manganese (VII) copper (I) lead (II) iron (III) iron (II) vanadium (V) vanadium (III) chromium (VI) chromium (III) cobalt (II)gold (I) lead (IV) cobalt (III)gold (III) Cr 3+ Cr 6+ V 3+ V 5+ Fe 2+ Fe 3+ Pb 2+ Pb 4+ Au + Au 3+ Co 3+ Co 2+ Sn 4+ Sn 2+ Cu 2+ Cu + Mn 7+ Mn 6+ Mn 4+ Mn 3+ Mn 2+ METALS THAT FORM MORE THAN ONE CATION*

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Polyatomic Ions--A Partial List NH 4 + ammoniumCO 3 2- carbonate NO 3 - nitrateHCO 3 - bicarbonate NO 2 - nitrite SO 4 2- sulfate SO 3 2- sulfiteClO 4 - perchlorate HSO 4 - bisulfateClO 3 - chlorate PO 4 3- phosphate ClO 2 - chlorite PO 3 3- phosphite ClO - hypochlorite HPO 4 2- hydrogen phosphate H 2 PO 4 2- dihydrogen phosphate OH - hydroxideMnO 4 - permanganate CN - cyanideCr 2 O 7 2- dichromate C 2 H 3 O 2 - acetateCrO 4 2- chromate O 2 2- peroxide

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Ionic Compounds  Ionic compounds (such as NaCl) are generally formed between metals and nonmetals.  Electrons are transferred from the metal to the nonmetal. The oppositely charged ions attract each other. Only empirical formulas are written.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Writing Formulas Because compounds are electrically neutral, one can determine the formula of a compound this way: –The charge on the cation becomes the subscript on the anion. –The charge on the anion becomes the subscript on the cation. –If these subscripts are not in the lowest whole- number ratio, divide them by the greatest common factor.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Formulas of Ionic Compounds Usually the same as their empirical formulas Made up of ions -- actually, a 1:1 ratio of cations to anions Ionic compound itself is electrically neutral -- SUM OF POSITIVE and NEGATIVE CHARGES MUST EQUAL ZERO!! PRINCIPLE OF CHARGE BALANCE applied to formulas of ionic compounds: The subscript of the cation is numerically equal to the charge on the anion, AND the subscript of the anion is numerically equal to the charge on the cation. MORE TO COME…

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. CHARGE BALANCE: How it works 1. Ionic compounds are electrically NEUTRAL; that is, their overall charge equals ZERO. Examples: CrO 3 and CrCl 3 Both CrO 3 and CrCl 3 have an overall charge of zero. 2. Simple anions have known negative charges. The oxide anion, O 2-, in CrO 3 has a -2 charge. The chloride anion, Cl -, in CrCl 3 has a -1 charge. 3. The SUM of the positive charge from the cation and the negative charge of the anion must equal ZERO. This is the principle of charge balance. Use algebra to set up an expression to solve for the charge on Cr for each compound: Let x = charge on Cr in CrCl 3. (1)x + (3)(-1) = 0 OR x + (3)(-1) = 0 (no. of metal cations)(charge on cation) + (no. of nonmetal anions)(charge on anion) = 0

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. CHARGE BALANCE: How it works 4. Determine the charge on the metal cation. (no. of metal cations)(charge on cation) + (no. of nonmetal anions)(charge on anion) = 0 x + (3)(-1) = 0 x - 3 = 0 ; x = 3  This is the charge on Cr in CrCl 3. Now, you try this one: What is the charge on Cr in CrO 3 ?

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Formula of Ionic Compounds Al 2 O 3 2 x +3 = +63 x -2 = -6 Al 3+ O 2- CaBr 2 1 x +2 = +22 x -1 = -2 Ca 2+ Br - Na 2 CO 3 1 x +2 = +21 x -2 = -2 Na + CO 3 2-

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Formulas of Ionic Compounds OK, so we know the charges on the cation and anion, respectively… So, how do we write formulas of ionic compounds in this case? (no. of metal cations)(charge on cation) + (no. of nonmetal anions)(charge on anion) = 0 Try these… potassium iodide zinc fluoride iron (III) oxide

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. (d) Magnesium sulfide (e) cobalt(II) chloride (f) Aluminum oxide

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. (d) Strontium hydroxide (e) Sodium carbonate (f) Ammonium phosphate

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. What is the formula for mercury (I) carbide?

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Homework is a worksheet

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Hwk: page 73-79: 5, 7, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. LESSON 4

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Inorganic Nomenclature Write the name of the cation. If the cation can have more than one possible charge, write the charge as a Roman numeral in parentheses. If the anion is an element, change its ending to -ide; if the anion is a polyatomic ion, simply write the name of the polyatomic ion.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Patterns in Oxyanion Nomenclature When there are two oxyanions involving the same element –the one with fewer oxygens ends in -ite. –the one with more oxygens ends in -ate. NO 2 − : nitrite; NO 3 − : nitrate SO 3 2− : sulfite; SO 4 2− : sulfate

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Patterns in Oxyanion Nomenclature Central atoms on the second row have a bond to, at most, three oxygens; those on the third row take up to four. Charges increase as you go from right to left.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Patterns in Oxyanion Nomenclature The one with the second fewest oxygens ends in -ite: ClO 2 − is chlorite. The one with the second most oxygens ends in -ate: ClO 3 − is chlorate. The one with the fewest oxygens has the prefix hypo- and ends in -ite: ClO − is hypochlorite. The one with the most oxygens has the prefix per- and ends in -ate: ClO 4 − is perchlorate.

© 2015 Pearson Education, Inc. Name the anion obtained by removing one oxygen atom from the perbromate ion, BrO 4–. a.Hypobromite ion b.Bromite ion c.Bromate ion d.Bromine ion

© 2015 Pearson Education, Inc. Name the anion obtained by removing one oxygen atom from the perbromate ion, BrO 4–. a.Hypobromite ion b.Bromite ion c.Bromate ion d.Bromine ion

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Acid Nomenclature If the anion in the acid ends in -ide, change the ending to -ic acid and add the prefix hydro-. –HCl: hydrochloric acid –HBr: hydrobromic acid –HI: hydroiodic acid If the anion ends in -ite, change the ending to -ous acid. –HClO: hypochlorous acid –HClO 2 : chlorous acid If the anion ends in -ate, change the ending to -ic acid. –HClO 3 : chloric acid –HClO 4 : perchloric acid

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Nomenclature of Binary Molecular Compounds The name of the element farther to the left in the periodic table (closer to the metals) or lower in the same group is usually written first. A prefix is used to denote the number of atoms of each element in the compound (mono- is not used on the first element listed, however).

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Nomenclature of Binary Compounds The ending on the second element is changed to -ide. –CO 2 : carbon dioxide –CCl 4 : carbon tetrachloride If the prefix ends with a or o and the name of the element begins with a vowel, the two successive vowels are often elided into one. –N 2 O 5 : dinitrogen pentoxide

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Nomenclature of Organic Compounds Organic chemistry is the study of carbon. Organic chemistry has its own system of nomenclature. The simplest hydrocarbons (compounds containing only carbon and hydrogen) are alkanes. The first part of the names just listed correspond to the number of carbons (meth- = 1, eth- = 2, prop- = 3, etc.).

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Nomenclature of Organic Compounds When a hydrogen in an alkane is replaced with something else (a functional group, like -OH in the compounds above), the name is derived from the name of the alkane. The ending denotes the type of compound. –An alcohol ends in -ol.

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Hwk: page 73-79:

Atoms, Molecules, and Ions © 2015 Pearson Education, Inc. Review Questions Chapter 2

© 2015 Pearson Education, Inc. The nucleus of an atom contains a.protons and neutrons. b.protons and electrons. c.electrons and neutrons. d.protons, neutrons, and electrons.

© 2015 Pearson Education, Inc. The nucleus of an atom contains a.protons and neutrons. b.protons and electrons. c.electrons and neutrons. d.protons, neutrons, and electrons.

© 2015 Pearson Education, Inc. Two atoms with the same atomic number but different mass numbers are called a.mutants. b.isomers. c.isotopes. d.symbiots.

© 2015 Pearson Education, Inc. Two atoms with the same atomic number but different mass numbers are called a.mutants. b.isomers. c.isotopes. d.symbiots.

© 2015 Pearson Education, Inc. Select the incorrect statement about the mass and volume of an atom. a.The mass is determined mostly by the protons and neutrons. b.The volume is mostly empty space. c.The mass is concentrated in the nucleus. d.The volume is determined by the arrangement of the protons.

© 2015 Pearson Education, Inc. Select the incorrect statement about the mass and volume of an atom. a.The mass is determined mostly by the protons and neutrons. b.The volume is mostly empty space. c.The mass is concentrated in the nucleus. d.The volume is determined by the arrangement of the protons.

© 2015 Pearson Education, Inc. For an atom of fluorine, the atomic number is ___ and the average atomic mass is ___. a.9; amu b ; 9 amu c.10; 19 g d.9; 9 g

© 2015 Pearson Education, Inc. For an atom of fluorine, the atomic number is ___ and the average atomic mass is ___. a.9; amu b ; 9 amu c.10; 19 g d.9; 9 g

© 2015 Pearson Education, Inc. Atomic weights on the periodic table are decimal numbers instead of integers because a.the number of protons + neutrons determines atomic weight. b.of the existence of isotopes. c.of the very small mass of electrons compared to protons and neutrons. d.the number of protons + electrons determines atomic weight.

© 2015 Pearson Education, Inc. Atomic weights on the periodic table are decimal numbers instead of integers because a.the number of protons + neutrons determines atomic weight. b.of the existence of isotopes. c.of the very small mass of electrons compared to protons and neutrons. d.the number of protons + electrons determines atomic weight.

© 2015 Pearson Education, Inc. The elements found on the right side of the periodic table tend to ______ electrons. a.gain b.lose c.keep d.share

© 2015 Pearson Education, Inc. The elements found on the right side of the periodic table tend to ______ electrons. a.gain b.lose c.keep d.share

© 2015 Pearson Education, Inc. Metals and nonmetals react to form ________ compounds. a.molecular b.mixed c.empirical d.ionic

© 2015 Pearson Education, Inc. Metals and nonmetals react to form ________ compounds. a.molecular b.mixed c.empirical d.ionic

© 2015 Pearson Education, Inc. Positive ions are called a.positrons. b.anions. c.cations. d.nucleons.

© 2015 Pearson Education, Inc. Positive ions are called a.positrons. b.anions. c.cations. d.nucleons.

© 2015 Pearson Education, Inc. Compounds composed only of carbon and hydrogen are called a.binary acids. b.carbohydrates. c.hydrocarbons. d.alkanes.

© 2015 Pearson Education, Inc. Compounds composed only of carbon and hydrogen are called a.binary acids. b.carbohydrates. c.hydrocarbons. d.alkanes.

© 2015 Pearson Education, Inc. The elements located in Group VIIA (Group 17) on the periodic table are called a.alkali metals. b.noble gases. c.chalcogens. d.halogens.

© 2015 Pearson Education, Inc. The elements located in Group VIIA (Group 17) on the periodic table are called a.alkali metals. b.noble gases. c.chalcogens. d.halogens.

© 2015 Pearson Education, Inc. Which of the formulas below does not represent a compound that actually exists? a.CaCO 3 b.H 2 O 2 c.KMnO 4 d.Na 2 PO 3

© 2015 Pearson Education, Inc. a.CaCO 3 b.H 2 O 2 c.KMnO 4 d.Na 2 PO 3 Which of the formulas below does not represent a compound that actually exists?

© 2015 Pearson Education, Inc. Which name is incorrectly paired with the formula? a.hydroxide ion; OH – b.barium(II) chloride; BaCl 2 c.ammonia; NH 3 d.sulfur dioxide; SO 2

© 2015 Pearson Education, Inc. Which name is incorrectly paired with the formula? a.hydroxide ion; OH – b.barium(II) chloride; BaCl 2 c.ammonia; NH 3 d.sulfur dioxide; SO 2

© 2015 Pearson Education, Inc. Acids produce _____ ions. a.OH –1 b.OH +1 c.H +1 d.H –1

© 2015 Pearson Education, Inc. Acids produce _____ ions. a.OH –1 b.OH +1 c.H +1 d.H –1

© 2015 Pearson Education, Inc. NaOCl is named a.sodium chlorate. b.sodium chlorite. c.sodium perchlorate. d.sodium hypochlorite.

© 2015 Pearson Education, Inc. NaOCl is named a.sodium chlorate. b.sodium chlorite. c.sodium perchlorate. d.sodium hypochlorite.

© 2015 Pearson Education, Inc. LiNO 3 is named a.lithium nitrate. b.lanthanum nitrate. c.lanthanum nitrite. d.lithium nitrite.

© 2015 Pearson Education, Inc. LiNO 3 is named a.lithium nitrate. b.lanthanum nitrate. c.lanthanum nitrite. d.lithium nitrite.

© 2015 Pearson Education, Inc. The formula for aluminum carbonate is a.Al 2 (CO 3 ) 3. b.AlCO 3. c.Al 2 C 3. d.Al 3 (CO 3 ) 2.

© 2015 Pearson Education, Inc. The formula for aluminum carbonate is a.Al 2 (CO 3 ) 3. b.AlCO 3. c.Al 2 C 3. d.Al 3 (CO 3 ) 2.

© 2015 Pearson Education, Inc. Fe 2 O 3 is named a.diiron trioxide. b.iron(III) oxide. c.ferrous oxide. d.ironic oxide.

© 2015 Pearson Education, Inc. Fe 2 O 3 is named a.diiron trioxide. b.iron(III) oxide. c.ferrous oxide. d.ironic oxide.

© 2015 Pearson Education, Inc. Which acid is not an oxyacid? a.hydrochloric acid b.nitric acid c.sulfurous acid d.acetic acid

© 2015 Pearson Education, Inc. Which acid is not an oxyacid? a.hydrochloric acid b.nitric acid c.sulfurous acid d.acetic acid

© 2015 Pearson Education, Inc. HIO 4 is named a.iodic acid. b.iodous acid. c.periodic acid. d.hydrogen iodate.

© 2015 Pearson Education, Inc. HIO 4 is named a.iodic acid. b.iodous acid. c.periodic acid. d.hydrogen iodate.

© 2015 Pearson Education, Inc. Cl 2 O 7 is named a.chlorine(VII) oxide. b.dichlorine hexaoxide. c.dichlorine heptaoxide. d.bichlorine heptaoxide.

© 2015 Pearson Education, Inc. Cl 2 O 7 is named a.chlorine(VII) oxide. b.dichlorine hexaoxide. c.dichlorine heptaoxide. d.bichlorine heptaoxide.

© 2015 Pearson Education, Inc. C 3 H 8 is named a.ethane. b.propane. c.propanol. d.pentane.

© 2015 Pearson Education, Inc. C 3 H 8 is named a.ethane. b.propane. c.propanol. d.pentane.

© 2015 Pearson Education, Inc. TEST