Chapter 4 Lecture Basic Chemistry Fourth Edition Chapter 4 Atoms and Elements 4.1 Elements and Symbols Learning Goal Given the name of an element, write its correct symbol; from the symbol, write the correct name. © 2014 Pearson Education, Inc.

Aluminum, AlSilver, Ag Gold, Au Sulfur, S Names and Symbols of Elements

© 2014 Pearson Education, Inc. Select the correct symbol for each element: A. Calcium(1) C(2) Ca(3) CA B. sulfur (1) S(2) Sl(3) Su C. iron(1) Ir(2) FE(3) Fe D. sodium(1) S(2) So(3) Na E. magnesium(1) Mg(2) Mn(3) Ma Learning Check

© 2014 Pearson Education, Inc. Select the correct symbol for each element: A. calcium (2) Ca B. sulfur (1) S C. iron(3) Fe D. sodium(3) Na E. magnesium(1) Mg Solution

© 2014 Pearson Education, Inc. Select the correct element name for each symbol: A. N(1) neon (2) nitrogen B. P(1) potassium(2) phosphorus C. Ag(1) silver(2) gold D. K(1) krypton(2) potassium E. F(1) fluorine(2) fempto Learning Check

© 2014 Pearson Education, Inc. Select the correct element name for each symbol: A. N(2) nitrogen B. P(2) phosphorus C. Ag(1) silver D. K(2) potassium E. F(1) fluorine Solution

Chapter 4 Lecture Basic Chemistry Fourth Edition Chapter 4 Atoms and Elements 4.2 The Periodic Table Learning Goal Use the periodic table to identify the group and the period of an element; identify the element as a metal, a nonmetal, or a metalloid. © 2014 Pearson Education, Inc.

In 1872, Dmitri Mendeleev created the periodic table arranged elements by increasing atomic mass arranged elements into groups with similar properties © 2014 Pearson Education, Inc. The Periodic Table

© 2014 Pearson Education, Inc. The Periodic Table

© 2014 Pearson Education, Inc. Group Numbers

© 2014 Pearson Education, Inc. Metals, Nonmetals, and Metalloids The heavy zigzag line on the periodic table separates the metals from nonmetals. Metalloids border the zigzag line.

© 2014 Pearson Education, Inc. Learning Check Match the elements to the description: A.Metals in Group 4A (14) (1) Sn, Pb(2) C, Si(3) C, Si, Ge, Sn B.Nonmetals in Group 5A (15) (1) As, Sb, Bi(2) N, P(3) N, P, As, Sb C.Metalloids in Group 4A (14) (1) C, Si, Ge(2) Si, Ge(3) Si, Ge, Sn, Pb

© 2014 Pearson Education, Inc. Solution Match the elements to the description: A.Metals in Group 4A (14) (1) Sn, Pb B.Nonmetals in Group 5A (15) (2) N, P C.Metalloids in Group 4A (14) (2) Si, Ge

Chapter 4 Lecture Basic Chemistry Fourth Edition Chapter 4 Atoms and Elements 4.3 The Atom Learning Goal Describe the electrical charge and location in an atom for a proton, a neutron and an electron. © 2014 Pearson Education, Inc.

The idea of atoms did not become scientific theory until John Dalton (1766–1844) developed an atomic theory proposing that atoms were responsible for the combinations of elements in compounds. Dalton's Atomic Theory

© 2014 Pearson Education, Inc. By the end of the 1880s, experiments with electricity showed that atoms were composed of tiny particles, called subatomic particles including protons, neutrons, and electrons it was shown that some subatomic particles in an atom have charge Electrical Charges in an Atom

© 2014 Pearson Education, Inc. In 1897, J. J. Thomson discovered that cathode rays were streams of small negatively charged particles called electrons proposed the “plum pudding” model of an atom in which protons and electrons were distributed throughout the atom Structure of an Atom

© 2014 Pearson Education, Inc. In 1911, Ernest Rutherford worked with J. J. Thomson and developed a new structure for the atom based on Rutherford’s gold foil experiments. Structure of an Atom

© 2014 Pearson Education, Inc. From the gold foil experiments, Rutherford realized that atoms contained a small region in the center with positive charge called the nucleus a region of space around the center of the atoms occupied by electrons The Structure of an Atom

© 2014 Pearson Education, Inc. In 1932, James Chadwick discovered that the nucleus of the atom also contained neutral particles called neutrons. The Structure of an Atom In an atom, the protons and neutrons that make up almost all the mass of the atom are packed into the tiny volume of the nucleus. The rapidly moving electrons (negative charge) surround the nucleus and account for the large volume of the atom.

© 2014 Pearson Education, Inc. Mass of the Atom The mass of the atom is due to the protons and neutrons in the nucleus. Electrons have a much smaller mass. Chemists use a unit called atomic mass unit (amu), defined as one-twelfth of the mass of the carbon atom with 6 protons and 6 neutrons. The mass of all elements in the periodic table is compared to the mass of this carbon atom.

© 2014 Pearson Education, Inc. Is each of the following statements true or false? A.The mass of an electron is greater than the mass of a proton. B.Protons have a positive charge, and electrons have a negative charge. C.The nucleus of an atom contains only the protons and neutrons. Learning Check

© 2014 Pearson Education, Inc. Is each of the following statements true or false? A.The mass of an electron is greater than the mass of a proton.False B.Protons have a positive charge, and electrons have a negative charge. True C.The nucleus of an atom contains only the protons and neutrons.True Solution

Chapter 4 Lecture Basic Chemistry Fourth Edition Chapter 4 Atoms and Elements 4.4 Atomic Number and Mass Number Learning Goal Given the atomic number and the mass number of an atom, state the number of protons, neutrons, and electrons. © 2014 Pearson Education, Inc.

The atomic number is specific for each element and the same for all atoms of that element is equal to the number of protons in an atom appears above the symbol of an element Atomic Number Chemical Symbol © 2014 Pearson Education, Inc. Atomic Number 11 Na

© 2014 Pearson Education, Inc. The mass number represents the number of particles in the nucleus is equal to the number of protons + number of neutrons does not appear on the periodic table because it applies to a single atom only Mass Numbers

© 2014 Pearson Education, Inc. We calculate the number of neutrons in an atom from its mass number and atomic number: mass number – atomic number = number neutrons Potassium has a mass number of 39 and an atomic number of 19. To find the number of neutrons, subtract the atomic number from its mass number. 39 (mass number) – 19( atomic number) = 20 neutrons Mass Numbers - Neutrons

© 2014 Pearson Education, Inc. An atom of zinc has a mass number of 65. A. How many protons are in the nucleus? (1) 30 (2) 35(3) 65 B.How many neutrons are in the nucleus? (1) 30(2) 35(3) 65 C. What is the mass number of a zinc atom that has 37 neutrons? (1) 37(2) 65(3) 67 Learning Check

© 2014 Pearson Education, Inc. An atom of zinc has a mass number of 65. A. How many protons are in the nucleus? (1) 30 B.How many neutrons are in the nucleus? (2) 35 C. What is the mass number of a zinc atom that has 37 neutrons? (3) 67 Solution

Chapter 4 Lecture Basic Chemistry Fourth Edition Chapter 4 Atoms and Elements 4.5 Isotopes and Atomic Mass Learning Goal Give the number of protons, electrons, and neutrons in one or more of the isotopes of an element; calculate the atomic mass of an element using the percent abundance and mass of its naturally occurring isotopes. © 2014 Pearson Education, Inc.

Isotopes are atoms of the same element that have different mass numbers have the same number of protons, but different numbers of neutrons © 2014 Pearson Education, Inc. Isotopes

© 2014 Pearson Education, Inc. An atomic symbol represents a particular isotope of an element gives the mass number in the upper left corner and the atomic number in the lower left corner mass number Atomic Symbols Chemical Symbol atomic number

© 2014 Pearson Education, Inc. Calculating Atomic Mass The calculation for the atomic mass requires the percent(%) abundance of each isotope atomic mass of each isotope of that element To calculate atomic mass of an element with 2 isotopes: mass isotope(1) × (%)/100 + mass isotope(2) × (%)/100 Atomic mass of element

© 2014 Pearson Education, Inc. Isotope Mass Abundance 24 Mg = amu × 78.70/100 = amu 25 Mg = amu × 10.13/100 = amu 26 Mg = amu × 11.17/100 = amu Atomic mass of Mg = amu Calculating Atomic Mass 12 Mg 24.31

© 2014 Pearson Education, Inc. Calculating Atomic Mass of Chlorine 35 Cl has a mass of amu (75.76%), and 37 C has a mass of amu (24.24%). Use the atomic mass and percent of each isotope to calculate the weighted average amu × 75.76/100 = amu amu × 24.24/100 = amu Atomic mass of Cl amu

© 2014 Pearson Education, Inc. Learning Check Gallium is an element found in lasers used in compact disc players. In a sample of gallium, there is 60.11% of 69 Ga (68.93 amu) atoms and 39.89% of 71 Ga (70.92 amu) atoms. Given the abundance and mass of these isotopes, calculate the atomic mass of gallium.

© 2014 Pearson Education, Inc. Solution Given the abundance and mass of these isotopes, calculate the atomic mass of gallium. 69 Ga amu × 60.11/100 = amu 71 Ga70.92 amu × 39.89/100 = amu Atomic mass Ga = amu