Unit 4: The Atom, And Isotopes #5 PPT APE MAN AND ISOTOPES! Unit 4: The Atom, Atomic Number, Mass Number, And Isotopes LecturePLUS Timberlake 1

LecturePLUS Timberlake Atomic Theory Atoms are building blocks of elements Similar atoms in each element Different from atoms of other elements Two or more different atoms bond in simple ratios to form compounds LecturePLUS Timberlake 2 2

LecturePLUS Timberlake Subatomic Particles Particle Symbol Charge Relative Mass Electron e- 1- 0 Proton p+ + 1 Neutron n 0 1 LecturePLUS Timberlake 3

Location of Subatomic Particles electrons protons neutrons nucleus LecturePLUS Timberlake 4

LecturePLUS Timberlake Atomic Number Counts the number of protons (+) in an atom LecturePLUS Timberlake 5

LecturePLUS Timberlake Periodic Table Represents physical and chemical behavior of elements Arranges elements by increasing atomic number Repeats similar properties in columns known as chemical families or groups LecturePLUS Timberlake 6

LecturePLUS Timberlake Periodic Table 1 2 3 4 5 6 7 8 11 Na LecturePLUS Timberlake 7

Atomic Number on the Periodic Table 11 Na Atomic Number Symbol LecturePLUS Timberlake 8

All atoms of an element have the same number of protons 11 Na 11 protons Sodium LecturePLUS Timberlake 9

LecturePLUS Timberlake Learning Check 1 State the number of protons for atoms of each of the following: A. Nitrogen 1) 5 protons 2) 7 protons 3) 14 protons B. Sulfur 1) 32 protons 2) 16 protons 3) 6 protons C. Barium 1) 137 protons 2) 81 protons 3) 56 protons LecturePLUS Timberlake 10

LecturePLUS Timberlake Solution 1 State the number of protons for atoms of each of the following: A. Nitrogen 2) 7 protons B. Sulfur 2) 16 protons C. Barium 3) 56 protons LecturePLUS Timberlake 11

LecturePLUS Timberlake Number of Electrons An atom is neutral The net charge is zero Number of protons = Number of electrons Atomic number = Number of electrons APE! A=P=E LecturePLUS Timberlake 12

protons (Atomic number) and neutrons Mass Number Counts the number of protons (Atomic number) and neutrons in an atom MAN! M=A+N or M-A=N LecturePLUS Timberlake 13

LecturePLUS Timberlake Atomic Symbols Show the mass number and atomic number Give the symbol of the element mass number Name: 23 Na sodium-23 atomic number 11 LecturePLUS Timberlake 14

LecturePLUS Timberlake More Atomic Symbols 16 31 65 O P Zn 8 15 30 8 p+ 15 p+ 30 p+ 8 n 16 n 35 n 8 e- 15 e- 30 e- LecturePLUS Timberlake 15

LecturePLUS Timberlake Isotopes Atoms with the same number of protons, but different numbers of neutrons. Atoms of the same element (same atomic number) with different mass numbers Isotopes of chlorine 35Cl 37Cl 17 17 chlorine - 35 chlorine - 37 LecturePLUS Timberlake 16

C Mass # Atomic # Isotopes 12 6 Nuclear symbol: Atoms of the same element with different mass numbers. 12 6 C Nuclear symbol: Mass # Each isotope has a different number of neutrons. Atomic # Hyphen notation: carbon-12 17 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem 17

Isotopes 18 + + Carbon-12 Neutrons 6 Protons 6 Electrons6 Carbon-14 Nucleus Neutron Proton + Electrons Nucleus Nucleus Neutron Proton + Carbon-12 Neutrons 6 Protons 6 Electrons6 Electrons The chemistry of each element is determined by its number of protons and electrons. In a neutral atom, the number of electrons equals the number of protons. Symbols for elements are derived directly from the element’s name. Nuclei of atoms contain neutrons as well as protons. The number of neutrons is not fixed for most elements, unlike protons. Atoms that have the same number of protons, and hence the same atomic number, but different numbers of neutrons are called isotopes. Carbon-14 Neutrons 8 Protons 6 Electrons6 Nucleus 18 18

6Li 7Li 3 p+ 3 p+ 2e– 1e– 2e– 1e– 4 n0 3 n0 + + 19 Lithium-6 Lithium-7 Nucleus Neutron Proton Nucleus Neutron Proton + Electrons Nucleus Electrons + Nucleus Lithium-6 Lithium-7 Neutrons 3 Protons 3 Electrons 3 Neutrons 4 Protons 3 Electrons 3 19 19

Cl Isotopes Cl Chlorine-37 20 atomic #: 17 mass #: 37 # of protons: 17 # of electrons: 17 # of neutrons: 20 37 17 Cl Atoms that have the same number of protons, and hence the same atomic number, but different numbers of neutrons are called isotopes. 20 20

Isotopes C-12 vs. C-14 Dalton was wrong. Atoms of the same element can have different numbers of neutrons different mass numbers called isotopes protons remain same The word isotope comes from the Greek words isos, meaning "equal," and topos, meaning "place." C-12 vs. C-14 21 California WEB 21

Naming Isotopes Put the mass number after the name of the element 22 carbon- 12 carbon -14 uranium-235 22 California WEB 22

LecturePLUS Timberlake Learning Check 2 Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of these carbon atoms. 12C 13C 14C 6 6 6 A. #P _______ _______ _______ B. #N _______ _______ _______ C. #E _______ _______ _______ LecturePLUS Timberlake 23

LecturePLUS Timberlake Solution 2 12C 13C 14C 6 6 6 A. #P __6___ _ 6___ ___6___ B. #N __6___ _ _7___ ___8___ C. #E __6___ _ 6___ ___6___ LecturePLUS Timberlake 24

LecturePLUS Timberlake Learning Check 3 An atom of zinc has a mass number of 65. A. Number of protons in the zinc atom 1) 30 2) 35 3) 65 B. Number of neutrons in the zinc atom C. What is the mass number of a zinc isotope with 37 neutrons? 1) 37 2) 65 3) 67 LecturePLUS Timberlake 25

LecturePLUS Timberlake Solution 3 An atom of zinc has a mass number of 65. A. Number of protons in the zinc atom 1) 30 B. Number of neutrons in the zinc atom 2) 35 C. What is the mass number of a zinc isotope with 37 neutrons? (MAN! M=A+N M= 30+37) 3) 67 LecturePLUS Timberlake 26

LecturePLUS Timberlake Learning Check 4 Write the atomic symbols for atoms with the following: A. 8 p+, 8 n, 8 e- ___________ B. 17p+, 20n, 17e- ___________ C. 47p+, 60 n, 47 e- ___________ LecturePLUS Timberlake 27

LecturePLUS Timberlake Solution 4 16O A. 8 p+, 8 n, 8 e- 8 B. 17p+, 20n, 17e- 37Cl 17 C. 47p+, 60 n, 47 e- 107Ag 47 LecturePLUS Timberlake 28

LecturePLUS Timberlake Learning Check 5 An atom has 14 protons and 20 neutrons. A. Its atomic number is 1) 14 2) 16 3) 34 B. Its mass number is C. The element is 1) Si 2) Ca 3) Se D. Another isotope of this element is 1) 34X 2) 34X 3) 36X 16 14 14 LecturePLUS Timberlake 29

LecturePLUS Timberlake Solution 5 An atom has 14 protons and 20 neutrons. A. It has atomic number 1) 14 B. It has a mass number of 3) 34 C. The element is 1) Si D. Another isotope of this element would be 3) 36X 14 LecturePLUS Timberlake 30

LecturePLUS Timberlake Masses of Atoms A scale designed for atoms gives their small atomic masses in atomic mass units (amu) An atom of 12C was assigned an exact mass of 12.00 amu Relative masses of all other atoms was determined by comparing each to the mass of 12C An atom twice as heavy has a mass of 24.00 amu. An atom half as heavy is 6.00 amu. LecturePLUS Timberlake 31

LecturePLUS Timberlake Atomic Mass Na 22.99 Listed on the periodic table Gives the mass of “average” atom of each element compared to 12C Weighted Average is based on all the isotopes and their abundance % Atomic mass is not a whole number LecturePLUS Timberlake 32

LecturePLUS Timberlake Learning Check 6 Using the periodic table, specify the atomic mass of each element (round to the tenths place): A. calcium __________ B. aluminum __________ C. lead __________ D. barium __________ E. iron __________ LecturePLUS Timberlake 33

LecturePLUS Timberlake Solution 6 Using the periodic table, specify the atomic mass of each element (round to the tenths place): A. calcium _40.1 amu _ B. aluminum _27.0 amu _ C. lead _207.2 amu_ D. barium _137.3 amu_ E. iron _55.8 amu__ LecturePLUS Timberlake 34

Calculating Atomic Mass Percent(%) abundance of isotopes Mass of each isotope of that element Weighted average = mass isotope1(%) + mass isotope2(%) + … 100 100 Weighted Average = (Mass#)(%) + (Mass#)(%) +... LecturePLUS Timberlake 35

Atomic Mass of Magnesium Isotopes Mass of Isotope Abundance 24Mg = 24.0 amu x 78.70% 25Mg = 25.0 amu x 10.13% 26Mg = 26.0 amu x 11.17% (then add) Atomic mass (average mass) Mg = 24.3 amu Mg 24.3 LecturePLUS Timberlake 36

LecturePLUS Timberlake Learning Check 7 Gallium is a metallic element found in small lasers used in compact disc players. In a sample of gallium, there is 60.2% of gallium-69 atoms and 39.8% of gallium-71 atoms. What is the atomic mass of gallium? LecturePLUS Timberlake 37

LecturePLUS Timberlake Solution 7 Ga-69 69 amu x 60.2 = 41.5 amu for 69Ga 100 Ga-71 71 amu x 39.8 = 28.3 amu for 71Ga ADD! Atomic mass Ga = 69.8 amu LecturePLUS Timberlake 38