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

2. 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

3. Subatomic Particles Particle Symbol Charge Relative Mass
Electron e
Proton p
Neutron n

4. 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

5. Atomic Number
Counts the number of
protons
in an atom

6. Atomic Number on the Periodic Table11 Na
Atomic Number
Symbol

7. All atoms of an element have the same number of protons11 Na
11 protons
Sodium

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

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

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

11. 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

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

13. 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

14. 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

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

16. Isotopes of Hydrogen

17. Isotopes of Hydrogen

18. Isotopes of Carbon

19. Isotopes of Carbon

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

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

22. 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 C 14C #p #n #e

23. 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 C 14C #p #n #e

24. 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- _______

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

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

27. 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

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

29. 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

30. 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

31. 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

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

33. 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 Pa 91

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

35. 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 Pt 78

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

37. 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

38. 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%

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

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

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