1. Subatomic Particles, Atomic Number and Atomic Mass

2. Subatomic particles Actual e- -1 p+ +1 no mass (g) Relative mass Name
Symbol
Charge
Electron e- -1
1/1840
9.11 x 10-28
Proton p+ +1 1
1.67 x 10-24
Neutron no 1
1.67 x 10-24

3. Structure of the Atom There are two regions: 1. The Nucleus:
With protons and neutrons
Positive charge
Almost all the mass
2. Electron cloud
Most of the volume of an atom
The region where the electron can be found

4. If the atom was the size of a stadium,
If the atom was the size of a stadium,
the nucleus would be the size of:
a marble.

5. Symbols
Contain the symbol of the element, the mass number and the atomic number X
Mass
number
Atomic
# protons
+ # neutrons
mass number
# protons

6. F Symbols 19 9 Find the number of protons number of neutrons
Symbols
Find the
number of protons
number of neutrons
number of electrons
Atomic number
Mass number
= 9 + F 19 9
= 10
= 9
= 9
= 19

7. Br Symbols 80 35 Find the number of protons number of neutrons
number of electrons
Atomic number
Mass number
= 35
= 45
= 35 Br 80 35
= 35
= 80

8. Na Symbols 23 11 Find the 1+ number of protons number of neutrons
number of electrons
Atomic number
Mass number
= 11 Na
= 12 23 1+
= 10 11
= 11
= 23
Sodium ion

9. http://www. webelements. com/webelements/elements/media/nearingzero/Na

10. Symbols
If a neutral atom of an element has 78 electrons and 117 neutrons what is the
Number of protons
Atomic number
Mass number
Complete symbol

13. X Mass number Atomic # protons + # neutrons mass number # protons X
Mass
number
Atomic
# protons
+ # neutrons
mass number
# protons

14. Isotopes
Atoms of the same element can have different numbers of neutrons
This gives them different mass numbers.
They have the same atomic numbers.
They look, act and react the same.
C vs C-14

16. Naming Isotopes Put the mass number after the name of the element
Examples:
Carbon-12 and Carbon-14
Uranium-235 and Uranium-238

19. Which isotopes are represented in this sketch?

20. Calculations of Average Atomic Mass
Why is the mass number on a periodic table never a nice whole number?

21. Mass Number vs AverageAtomic Mass
The Mass Number is specific to one isotope.
The Average Atomic Mass is the calculated based on the abundance of each naturally occurring isotope of that element.
The Average Atomic Mass is shown on Periodic Tables. It is the most accurate number that should be used in calculations.

22. Average Atomic Mass How heavy is an atom of oxygen?
There are different kinds of oxygen atoms.
oxygen-16,
oxygen-17 and
oxygen-18
We are more concerned with average atomic mass, based on the abundance of each element in nature.
We don’t use grams because the numbers would be too small.
California WEB

23. Atomic Mass Unit (amu or u) This unit is used instead of grams.
Atomic Mass Unit
(amu or u)
This unit is used instead of grams.
It is 1/12 of the mass of a carbon-12 atom.

24. Calculating averages
You have five rocks, four with a mass of 50 g, and one with a mass of 60 g. What is the average mass of the rocks?
California WEB

25. Calculating averages Total mass = (4 x 50) + (1 x 60) = 260 g
Average mass = (4 x 50) + (1 x 60) = 260 g
Average mass = 4 x x 60 = 260 g
Calculating averages
California WEB

26. Average mass = (4/5)50 + (1/5)60 = 260 g
80% of the rocks weigh 50 grams
20% of the rocks weigh 60 grams
We calculate atomic mass the same way.

27. Sample Problem
Calculate the average atomic mass of copper if copper has two isotopes % has a mass of u and the rest has a mass of u.
California WEB

28.
Average Atomic Mass
Calculate the average atomic mass of copper if copper has two isotopes % has a mass of u and the rest has a mass of u.
Isotope
Percent
Abundance
Mass
Cu-63
69.1
62.93
Cu-65
30.9
64.93 u Cu 29
63.548

29. Radioisotopes

30. Radioactive: Radioisotope:
Capable of spontaneously emitting radiation in the form of particles and/or gamma rays
Radioisotope:
A radioactive isotope of an element that occurs naturally or is produced artificially.

31. Radioisotopes
Many elements have one or more isotopes that are unstable.
Atoms of unstable isotopes decay, emitting radiation as their nucleus changes.
The changes can happen quickly or slowly, depending on the isotope.
Radiation emitted can be harmless or very dangerous to living cells.

32. Applications of Nuclear Science
Anthropology:
Radiology:
Nuclear Reactors:

35. Homework “Isotope Exercise” worksheet
Read pages of your textbook
Prepare a concept map of the key issues related to nuclear power and nuclear waste.

36. Concept Map Key Features: Contains key ideas Shows relationships
Benefits:
Helps you organize your thoughts
Increases understanding and retention of information
Great study tool

38. http://upload. wikimedia. org/wikipedia/en/thumb/3/3a/Conceptmap

41. Final Notes…
You concept map is an INDIVIDUAL activity. Each map should be original and significantly different from all others.
Personalize it the way that you want. Your map will be your reference notes.
Please do not computerize your map. This is too time consuming without the right software!

42. Main Source for Slides: