#5 PPT APE MAN AND ISOTOPES! Unit 4: The Atom, Atomic Number, Mass Number, And Isotopes LecturePLUS Timberlake 1
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
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 nucleus protons neutrons LecturePLUS Timberlake 4
Atomic Number Counts the number of protons (+) in an atom LecturePLUS Timberlake 5
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
Periodic Table 1 2 3 4 5 6 7 8 11 Na LecturePLUS Timberlake 7
Atomic Number on the Periodic Table Atomic Number Symbol 11 Na LecturePLUS Timberlake 8
All atoms of an element have the same number of protons 11 protons Sodium 11 Na LecturePLUS Timberlake 9
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
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
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
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
Atomic Symbols Show the mass number and atomic number Give the symbol of the element mass number Name: atomic number 11 23 Na sodium-23 LecturePLUS Timberlake 14
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
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 35 Cl 37 Cl 17 17 chlorine - 35 chlorine - 37 LecturePLUS Timberlake 16
Isotopes Atoms of the same element with different mass numbers. Nuclear symbol: Mass # Atomic # 6C 12 Hyphen notation: carbon-12 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem 17
Isotopes Nucleus Electrons + + + + + + Neutron Proton Nucleus Nucleus Carbon-12 Neutrons 6 Protons 6 Electrons6 Proton + + + + + + Neutron Electrons Carbon-14 Neutrons 8 Protons 6 Electrons6 Nucleus 18
6 Li 7 Li 3 p + 2e 3 n 0 1e 3 p + 2e 4 n 0 1e Neutron Nucleus Electrons + + + Nucleus Proton Nucleus Electrons + + + Neutron Proton Lithium-6 Neutrons 3 Protons 3 Electrons 3 Nucleus Lithium-7 Neutrons 4 Protons 3 Electrons 3 19
Chlorine-37 Isotopes atomic #: 17 mass #: 37 # of protons: 17 37 17 Cl 37 17Cl # of electrons: 17 # of neutrons: 20 20
Isotopes Dalton was wrong. Atoms of the same element can have different numbers of neutrons different mass numbers called isotopes protons remain same C-12 vs. C-14 California WEB 21
Naming Isotopes Put the mass number after the name of the element carbon- 12 carbon -14 uranium-235 California WEB 22
Learning Check 2 Naturally occurring carbon consists of three isotopes, 12 C, 13 C, and 14 C. State the number of protons, neutrons, and electrons in each of these carbon atoms. 12 C 13 C 14 C 6 6 6 A. #P B. #N C. #E LecturePLUS Timberlake 23
Solution 2 12 C 13 C 14 C 6 6 6 A. #P 6 6 6 B. #N 6 _7 8 C. #E 6 6 6 LecturePLUS Timberlake 24
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 1) 30 2) 35 3) 65 C. What is the mass number of a zinc isotope with 37 neutrons? 1) 37 2) 65 3) 67 LecturePLUS Timberlake 25
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
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
Solution 4 16 O A. 8 p +, 8 n, 8 e - 8 B. 17p +, 20n, 17e - 37 Cl 17 C. 47p +, 60 n, 47 e - 107 Ag 47 LecturePLUS Timberlake 28
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 1) 14 2) 16 3) 34 C. The element is 1) Si 2) Ca 3) Se D. Another isotope of this element is 1) 34 X 2) 34 X 3) 36 X 16 14 14 LecturePLUS Timberlake 29
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) 36 X 14 LecturePLUS Timberlake 30
Masses of Atoms A scale designed for atoms gives their small atomic masses in atomic mass units (amu) An atom of 12 C was assigned an exact mass of 12.00 amu Relative masses of all other atoms was determined by comparing each to the mass of 12 C An atom twice as heavy has a mass of 24.00 amu. An atom half as heavy is 6.00 amu. LecturePLUS Timberlake 31
Atomic Mass Na 22.99 Listed on the periodic table Gives the mass of average atom of each element compared to 12 C Weighted Average is based on all the isotopes and their abundance % Atomic mass is not a whole number LecturePLUS Timberlake 32
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
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 isotope 1 (%) + mass isotope 2 (%) + 100 100 Weighted Average = (Mass#)(%) + (Mass#)(%) +... LecturePLUS Timberlake 35
Atomic Mass of Magnesium Isotopes Mass of Isotope Abundance 24 Mg = 24.0 amu x 78.70% 25 Mg = 25.0 amu x 10.13% 26 Mg = 26.0 amu x 11.17% (then add) Atomic mass (average mass) Mg = 24.3 amu Mg 24.3 LecturePLUS Timberlake 36
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
Ga-69 Solution 7 69 amu x 60.2 = 41.5 amu for 69 Ga 100 Ga-71 71 amu x 39.8 = 28.3 amu for 71 Ga 100 ADD! Atomic mass Ga = 69.8 amu LecturePLUS Timberlake 38