Atomic Number and Mass Number Atomic Theory The Atom Atomic Number and Mass Number Isotopes

Modern Atomic Theory Atoms are building blocks of elements Similar atoms in each element (are they exactly the same?) Different from atoms of other elements Two or more different atoms bond in simple ratios to form compounds

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

Subatomic Particles Atomic Number = number of protons # of protons determines kind of atom the same as the number of electrons in the neutral atom Mass Number = the number of protons + neutrons protons and neutrons also called nucleons

Atomic Number Counts the number of protons in an atom

Atomic Number on the Periodic Table 11 Na Atomic Number Symbol

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

State the number of protons for atoms of each of the following: A. Nitrogen B. Sulfur C. Barium Lead Francium Tungsten

State the number of protons for atoms of each of the following: A. Nitrogen 7 B. Sulfur 16 C. Barium 56 Lead 82 Francium 87 Tungsten 74

Mass Number Counts the number of protons and neutrons in an atom

Atomic Symbols 22.9 Na 11 Show the mass number and atomic number Give the symbol of the element mass number 22.9 Na 11 atomic number

Determine the number of protons, electrons and neutrons in each of the following: Iron Oxygen Cobalt Manganese Uranium Bismuth

Determine the number of protons, electrons and neutrons in each of the following: Iron 26p, 30n Oxygen 8p, 8n Cobalt 27p, 32n Manganese 25p, 30n Uranium 92p, 146n Bismuth 83p, 126n

Isotopes Dalton was wrong. Atoms of the same element can have different numbers of neutrons A different number of neutrons means different mass numbers Isotopes of the same atom have different mass numbers

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 Hydrogen

Isotopes of Hydrogen

Isotopes of Carbon

Isotopes of Carbon

Naming Isotopes Put the mass number after the name of the element 12C is carbon -12 14C is carbon -14 235U is uranium-235

Isotopes Isotopes of chlorine 35Cl 37Cl 17 17 17 17 chlorine - 35 chlorine - 37

Determine the Following: 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 #p #n #e

Determine the Following: 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 #p 6 6 6 #n 6 7 8 #e 6 6 6

Complete the Following: 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- _______

Complete the Following: Write the atomic symbols for atoms with the following: A. 8 p+, 8 n, 8 e- 16O B. 17p+, 20n, 17e- 37Cl C. 47p+, 60 n, 47 e- 107Ag

F Symbols 19 9 Determine the: number of protons number of neutrons number of electrons Atomic number Mass Number 19 F 9

F Symbols 19 9 Determine the: number of protons – 9 number of neutrons - 10 number of electrons - 9 Atomic number - 9 Mass Number - 19 19 F 9

Br Symbols 80 35 Find the number of protons number of neutrons number of electrons Atomic number Mass Number 80 Br 35

Br Symbols 80 35 Find the number of protons -35 number of neutrons - 45 number of electrons - 35 Atomic number - 35 Mass Number - 80 80 Br 35

Symbols if an element has an atomic number of 34 and a mass number of 78 what is the number of protons number of neutrons number of electrons Complete symbol

Symbols if an element has an atomic number of 34 and a mass number of 78 what is the number of protons - 34 number of neutrons - 44 number of electrons - 34 Complete symbol – 78 Se 34

Symbols if an element has 91 protons and 140 neutrons what is the Atomic number Mass number number of electrons Complete symbol

Symbols if an element has 91 protons and 140 neutrons what is the Atomic number - 91 Mass number - 231 number of electrons - 91 Complete symbol 231 Pa 91

Symbols if an element has 78 electrons and 117 neutrons what is the Atomic number Mass number number of protons Complete symbol

Symbols if an element has 78 electrons and 117 neutrons what is the Atomic number - 78 Mass number - 195 number of protons - 78 Complete symbol 195 Pt 78

Atomic Mass Atomic mass is the weighted average mass of all the atomic masses of the isotopes of that atom.

Calculating Atomic Mass Atomic Masses are not whole numbers on the periodic table Atomic masses are the weighted average of all naturally occurring isotopes of that atom Weighted averages are the sum of the percent abundance of each isotope multiplied by its atomic mass

Calculating Percent Abundance You have five rocks, four with a mass of 50 g, and one with a mass of 60 g. What is the percent abundance of the rocks? Total number of rocks is 5 Percent Abundance of 50 g rocks: 4/5 = 80% Percent Abundance of 60 g rocks: 1/5 = 20%

Calculating Weighted Average = (50g x 0.80) + (60g x 0.20) = 40g + 12g = 52g

Atomic Mass Calculate the atomic mass of copper if copper has two isotopes. 69.1% has a mass of 62.93 amu and the rest has a mass of 64.93 amu.

Atomic Mass Atomic Mass = (0.691 x 62.93) + (0.309 x 64.93) Atomic Mass = 63.54 amu