Physical Science Chapter 17 Properties of Atoms and the Periodic Table Note: You will not be able to view the videos from the internet version of this presentation. Copyright laws prevent that option. 1

Unit 4 The Nature of Matter CLE: 32020.1.2. Describe the structure and arrangement of atomic particles.

17:1 Structure of the Atom Scientists have developed their own shorthand for dealing with long, complicated names. Chemical symbols consist of one capital letter or a capital letter plus one or two smaller letters.

17:1 Scientific Shorthand Elements are abbreviated in scientific shorthand—first letter or two of element’s name. DefinitionofAtoms 2.11

17:1 The Scientific Shorthand For some elements, the symbol is the first letter of the element's name. For other elements, the symbol is the first letter of the name plus another letter from its name. Because scientists worldwide use this system, everyone understands what the symbols mean. 5

17:1 Structure of the Atom Atomic Compounds Aluminum…Al Calcium……Ca Carbon…….C Chlorine……Cl Copper…….Cu Fluorine……F Gold………Au Helium……He Hydrogen…..H Iodine………I Iron………Fe Magnesium..Mg Memorize These. There will be quizzes often over the element and their symbols. STUDY. 6

17:1 Structure of the Atom Atomic Compounds Lead………..Pb Radium……Ra Chromium...Cr Zinc………Zn Neon………Ne Platinum…..Pt Sulfur………S Mercury….Hg Nitrogen….N Oxygen……O Potassium….K Silver………Ag Sodium…….Na Memorize These. There will be quizzes often over the element and their symbols. STUDY. 7

17.1 Irregular Chemical Symbols The chemical symbols for the following elements are not abbreviations of their English names. Copper is Cu, for cuprum. Gold is Au for aurum. Iron is Fe for ferrum. Lead is Pb for plumbum. Tin is Sn for stannum. Mercury is Hg for hydrargyrum. Silver is Ag for argentum. Sodium is Na for natrium. Potassium is K for kalium. Antimony is Sb for stibium and Tungsten is W for wolfram. 8

17:1 Structure of the Atom An element is matter that is composed of one type of atom. An atom is the smallest piece of matter that still retains the properties of the element. Atoms are composed of particles called protons, neutrons, and electrons. 9

Protons are particles with an electrical charge of 1+. 17:1 Atomic Components Protons and neutrons are found in a small positively charged center of the atom called the nucleus that is surrounded by a cloud containing electrons. Protons are particles with an electrical charge of 1+. 10

Protons and neutrons are made up of smaller particles called quarks. 17.1 Quarks—Even Smaller Particles Protons and neutrons are made up of smaller particles called quarks. So far, scientists have confirmed the existence of six uniquely different quarks. 11

Electrons are particles with an electrical charge of 1–. 17:1 Atomic Components Neutrons are neutral particles that do not have an electrical charge. Electrons are particles with an electrical charge of 1–. LookingInside2.34 12

17.1 Quarks—Even Smaller Particles Scientists theorize that protons are made of three quarks held together with the strong nuclear force. Another arrangement of three quarks produces a neutron. 13

17.1 Quarks—Even Smaller Particles Protons and neutrons are made up of smaller particles called quarks. Quarks are studied by colliding accelerated charged particles with protons, which leave tracks in a bubble chamber. Six quarks are known to exist; the sixth is called the top quark. 14

17:1 Models—Tools for Scientists Structure of the Atom 17:1 Models—Tools for Scientists Scientists and engineers use models to represent things that are difficult to visualize—or picture in your mind. Scaled-down models allow you to see either something too large to see all at once, or something that has not been built yet. Scaled-up models are often used to visualize things that are too small to see. 15

Scientists use scaled-up models to represent atoms. 17.1 Models—Tools for Scientists To study the atom, scientists have developed scaled-up models that they can use to visualize how the atom is constructed. Scientists use scaled-up models to represent atoms. 16

17.1 The Changing Atomic Model In the 1800s, John Dalton, an English scientist, was able to offer proof that atoms exist. Dalton use a sphere as an early model of the atom. Another famous Greek philosopher, Aristotle, disputed Democritus's theory and proposed that matter was uniform throughout and was not composed of smaller particles. 17

17.1 The Electron Cloud Model By 1926, scientists had developed the electron cloud model of the atom that is in use today. An electron cloud is the area around the nucleus of an atom where its electrons are most likely found. The electron cloud model shows electrons traveling around in specific energy levels around a nucleus of protons and neutrons. StructureofAtoms2.42

Question 1 Answer A. atom B. quark C. neutron D. proton Section Check Question 1 Which is the smallest piece of matter that still retains the property of the element? Answer A. atom B. quark C. neutron D. proton The answer is A. An atom is the smallest piece of matter that still retains the property of the element. 20

Question 2 What particles are found in the nucleus of an atom? A. protons and electrons B. protons and neutrons C. neutrons and electrons D. quarks and electrons 21

Answer The answer is B. Electrons are located in an electron cloud surrounding the nucleus of the atom. 22

Protons and neutrons are made of smaller particles called quarks. Question 3 What is the name of the small particles that make up protons and neutrons? Answer Protons and neutrons are made of smaller particles called quarks. 23

17.2 Atomic Mass The nucleus contains most of the mass of the atom because protons and neutrons are far more massive than electrons. The mass of a proton is about the same as that of a neutron. 24

17.2 Atomic Mass The mass of each proton and neutron is approximately 1,836 times greater than the mass of the electron. 25

17.2 Atomic Mass The unit of measurement used for atomic particles is the atomic mass unit (amu). The mass of a proton or a neutron is almost equal to 1 amu. The atomic mass unit is defined as one-twelfth the mass of a carbon atom containing six protons and six neutrons. 26

17.2 Protons Identify the Element The number of protons tells you what type of atom you have and vice versa. For example, every carbon atom has six protons. Also, all atoms with six protons are carbon atoms. The number of protons in an atom is equal to a number called the atomic number. 27

17.2 Mass Number The mass number of an atom is the sum of protons and neutrons in the nucleus of an atom. 28

17.2 Mass Number If you know the mass number and the atomic number of an atom, you can calculate the number of neutrons. number of neutrons = mass number – atomic number Atomic Mass2.09 Atomic Number2.55 29

Summary Learn These Facts. The atomic number is the number of protons. The number of protons is equal to the number of electrons. The number of neutrons is the mass number minus the protons. The number of neutrons plus the number of protons is the mass number. The elements on the periodic table are arranged by atomic numbers. Do the Practice Problems Now. 30

Element Symbol Atomic # Atomic Mass # P #N #E Helium He 2 4 Magnesium 12 Zinc 30 65 Bromine 80 35 Aluminum 13 14 Uranium U 146 92 Sodium 11 Krypton 48 36 Calcium 40 20 Silver 47 61 2 2 2 Mg 24 12 12 Zn 30 35 30 35 45 Br 35 13 13 27 Al 92 238 92 11 Na 11 23 Kr 36 84 36 Ca 20 20 20 Ag 47 47 34 108

Calculate the atomic mass of these compounds Calculate the atomic mass of these compounds. The unit for atomic mass is amu (atomic mass unit). PbO CuO HCl SO2 Al2O3 ZnCl3 Copy these problems into your notebook. Begin now. If you don’t finish, this is your homework for tonight.

Pb = 207.2 x 1 = 207.2 O = 15.999 x 1 = 15.999 223.199 amu Cu = 63.546 x 1 = 63.546 O = 15.999 x 1 = 15.999 79.545 amu PbO CuO

3. H = 1.008 x 1 = 1.008 Cl = 35.453 x 1 = 35.453 36.461 amu 4. S = 32.065 x 1 = 32.065 O2 = 15.999 x 2 = 31.998 64.063 amu HCl SO2

5. Al = 26.982 x 2 = 53.964 O3 = 15.999 x 3 = 47.997 101.961 amu 6. Zn = 65.409 x 1 = 65.409 Cl3 = 35.453 x 3 = 106.359 171.768 amu Al2O3 ZnCl3

17.2 Isotopes Not all the atoms of an element have the same number of neutrons. Atoms of the same element that have different numbers of neutrons are called isotopes. 33

17.2 Isotopes Models of two isotopes of boron are shown. Because the numbers of neutrons in the isotopes are different, the mass numbers are also different. You use the name of the element followed by the mass number of the isotope to identify each isotope: boron-10 and boron-11. 34

Isotopes Different isotopes have different properties. Number of neutrons is equal to mass number minus atomic number. Name of element followed by mass number identifies the isotope. Average atomic mass is the weighted-average mass of an element’s isotopes. Average atomic mass is closest to its most abundant isotope. 35

Isotopes4.18 17.2 Isotopes The average atomic mass of an element is the weighted-average mass of the mixture of its isotopes. For example, four out of five atoms of boron are boron-11, and one out of five is boron-10. To find the weighted-average or the average atomic mass of boron, you would solve the following equation: 37

How is the atomic number of an element determined? Section Check Question 1 How is the atomic number of an element determined? Answer The atomic number of an element is equal to the number of protons in an atom of that element. 40

Question 2 The element helium has a mass number of 4 and atomic number of 2. How many neutrons are in the nucleus of a helium atom? Answer Recall that the atomic number is equal to the number of protons in the nucleus. Since the mass number is 4 and the atomic number is 2, there must be 2 neutrons in the nucleus of a helium atom. 41

How much of the mass of an atom is contained in an electron? Question 3 How much of the mass of an atom is contained in an electron? Answer The electron’s mass is so small that it is considered negligible when finding the mass of an atom. 42

Organizing the Elements 17.3 The Periodic Table Organizing the Elements Periodic means "repeated in a pattern." In the late 1800s, Dmitri Mendeleev, a Russian chemist, devised the first periodic table based on atomic masses. 43

Organizing the Elements 17.3 The Periodic Table Organizing the Elements Because the pattern repeated, it was considered to be periodic. Today, this arrangement is called a periodic table of elements. In the periodic table, the elements are arranged by increasing atomic number and by changes in physical and chemical properties. 44

Mendeleev’s Predictions 17.3 The Periodic Table Mendeleev’s Predictions Mendeleev had to leave blank spaces in his periodic table to keep the elements properly lined up according to their chemical properties. Mendeleev looked at the properties and atomic masses of the elements surrounding these blank spaces. His periodic table was arranged based on atomic mass. 45

17.3 Improving the Periodic Table In 1913, the work of Henry G.J. Moseley, a young English scientist, made an arrangement of elements based on their increasing atomic numbers instead of an arrangement based on atomic masses. The current periodic table uses Moseley's arrangement of the elements. 49 UsingtheModernPT6.24

17.3 Electron Cloud Structure In a neutral atom, the number of electrons is equal to the number of protons. Therefore, a carbon atom, with an atomic number of six, has six protons and six electrons. 50

17.3 Electron Cloud Structure Scientists have found that electrons within the electron cloud have different amounts of energy. 51

17.3 Electron Cloud Structure Scientists model the energy differences of the electrons by placing the electrons in energy levels.

17.3 Electron Cloud Structure Energy levels nearer the nucleus have lower energy than those levels that are farther away. Electrons fill these energy levels from the inner levels (closer to the nucleus) to the outer levels (farther from the nucleus). 53

17.3 Electron Cloud Structure Elements that are in the same group have the same number of electrons in their outer energy level. It is the number of electrons in the outer energy level that determines the chemical properties of the element. 54

Energy level 2 can contain at most eight electrons. 17.3 Energy Levels For example, energy level one can contain a maximum of two electrons. Energy level 2 can contain at most eight electrons. 55

17.3 Energy Levels Each row in the periodic table ends when an outer energy level is filled. 56

17:2 Masses of Atoms Atomic Mass

Electron Dot Diagrams Elements that are in the same group have the same number of electrons in their outer energy level. These outer electrons are so important in determining the chemical properties of an element that a special way to represent them has been developed. 60

Electron Dot Diagrams An electron dot diagram uses the symbol of the element and dots to represent the electrons in the outer energy level. Electron dot diagrams are used also to show how the electrons in the outer energy level are bonded when elements combine to form compounds.

Same Group—Similar Properties Not all elements will combine readily with other elements. The elements in Group 18 have complete outer energy levels. This special configuration makes Group 18 elements relatively unreactive. 63

17.3 Regions on the Periodic Table The periodic table has several regions with specific names. The horizontal rows of elements on the periodic table are called periods. The elements increase by one proton and one electron as you go from left to right in a period. 64

17.3 Improving the Periodic Table The vertical columns in the periodic table are called groups, or families, and are numbered 1 through 18. Copy this to your notes. 65

17.3 Regions on the Periodic Table Elements are classified as metals, nonmetals and metalloids. All of the elements on the left side of the table are metals. 66

17.3 Regions on the Periodic Table Those elements on the right side of the periodic table, in yellow, are classified as nonmetals. 67

17.3 Regions on the Periodic Table The elements located on the stair-step dividing line are metalloids. 68

A Growing Family Element 112 was discovered at the same laboratory. In 1994, scientists at the Heavy-Ion Research Laboratory in Darmstadt, Germany, discovered element 111. Element 112 was discovered at the same laboratory. Both of these elements are produced in the laboratory by joining smaller atoms into a single atom. 69

Elements in the Universe The same elements exist throughout the universe. Elements are synthesized in laboratories all over the world. Hydrogen and helium are the building blocks of other elements. 70

Elements in the Universe Exploding stars, or supernovas, give scientists evidence to support this theory. Many scientists believe that supernovas have spread the heavier elements throughout the universe. 71

Calculation—Atomic Mass To calculate the atomic mass of a compound, add the atomic mass of each atom. Example FeBr3 Fe = 55.845 x 1 =55.85 Br = 79.904 x 3 = 239.712 239.712 + 55.85 = 296.557 amu 72

1. Ca(NO2)4 4. NaCl 2(H2SO4) 5. BaCl2 H2O 6. C6H12O6 18:3 The Periodic Table Calculate the average atomic mass of these compounds. 1. Ca(NO2)4 4. NaCl 2(H2SO4) 5. BaCl2 H2O 6. C6H12O6 Na x 1 = 22.990 Cl x 1 = 35.453 58.443 Ca x 1 =40.078 N x 4 = 56.028 O x 8 = 127.992 224.098 H x 4= 4.032 S x 2 =64.130 O x 8 =127.992 196.154 Ba x 1=137.327 Cl x 2 70.906 208.233 C x 6 = 72.066 H x 12 =12.096 O x 6 = 95.994 180.156 H x 2 = 2.016 O x 1 =15.999 18.015 73

Question 1 How are the elements arranged in the periodic table? Section Check Question 1 How are the elements arranged in the periodic table? 74

Answer The elements are arranged by increasing atomic number and by changes in physical and chemical properties. 75

Question 2 What do the elements in a vertical column of the periodic table have in common? Answer The vertical columns in the periodic table are called groups; elements in the same group have similar properties, such as electrical conductivity. 76

What do the dots in this electron dot diagram represent? Question 3 What do the dots in this electron dot diagram represent? 77

The dots represent the electrons in the outer energy level. Answer The dots represent the electrons in the outer energy level. 78

The central core of an atom is called the ______. 17. Review The central core of an atom is called the ______. The chart showing the classifications of elements according to their properties and increasing atomic numbers is called the __________. nucleus periodic table. 79

The mass of a ________ is about equal to the mass of a proton. 17. Review The mass of a ________ is about equal to the mass of a proton. Elements arranged in vertical columns in the periodic table are called _______. neutron groups 80

The symbol for chlorine is ________. 17. Review The region around the nucleus occupied by the electrons is called ________. The symbol for chlorine is ________. Electron cloud Cl 81

17. Review The maximum number of electrons in the second energy level of an atom is ________. Two isotopes of carbon are carbon -12 and carbon 14. These isotopes differ from one another by two ________. 8 neutrons 82

Metals are ___ conductors of heat and electricity. 17. Review Metals are ___ conductors of heat and electricity. Scientists believe that naturally occurring elements are manufactured within ____. good stars 83

17. Review So far, scientists have confirmed the existence of ___ different quarks. In 1926, scientists developed the ____ model of the atom that is used today. 6 Electron cloud 84

The atomic number of an element is determined by its number of ____. 17. Review Electron ____ are used to show how electrons in the outer energy level are bonded when elements combine to form compounds. The atomic number of an element is determined by its number of ____. Dot diagrams protons 85

17. Review According to present atomic theory, the location of an ____ in an atom cannot be pinpointed exactly. Moving from left to right in a row of the periodic table, metallic properties _____. electron decrease 86

Dot diagrams are used to represent____. 17. Review Each inner energy level of an atom has a maximum number of ____ it can hold. Dot diagrams are used to represent____. electrons Outer level electrons 87

Particles of matter that make up protons and neutrons are ____. 17. Review Particles of matter that make up protons and neutrons are ____. A chemical symbol represents the ____ of an element. quarks name 88

Horizontal rows of the periodic table are called _____. 17. Review Horizontal rows of the periodic table are called _____. Atoms of the same element with different numbers of neutrons are called _______. periods isotopes 89

A particle that moves around the nucleus is a(n) ______. 17. Review A particle that moves around the nucleus is a(n) ______. Elements that are gases , are brittle, and are poor conductors at room temperature are ______. electron nonmetals 90

17. Review A _____ is used to accelerate protons in the study of subatomic particles. A certain atom has 26 protons, 26 electrons and 30 neutrons. Its mass number is _____. tevatron 56 91

17. Review Suppose that you have discovered a new element and have named it neptunite. While studying your new element, you find that it has two isotopes –neptunite-220 and neptunite-250. What is the average atomic mass of your new element assuming that these two isotopes are present in equal amounts in nature? 235 amu 92

17. Review Assume that an element is composed of one isotope with a mass of 142 and another isotope with a mass of 145. For each atom with a mass of 142 there are three atoms with a mass of 145. What is the average atomic mass of the element? 144.25 93

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