1. Isotopes, Radioactivity, Decay

2. Review Atomic Structure

3. Isotope
An atom of the same element with a different number of neutrons
Examples
Carbon-12 has 6 protons and 6 neutrons
6 protons + 6 neutrons = 12 (mass number)
Carbon-14 has 6 protons and 8 neutrons
6 protons + 8 neutrons = 14 (mass number)

4. Hydrogen normally has 1 proton (Also called protium)
Mass number = 1
Hydrogen sometimes has 1 proton and 1 neutron (deuterium)
Mass number = 2
Hydrogen can also have 1 proton and 2 neutrons (tritium)
Mass number = 3

5. Which ones are isotopes?
Uranium-238
Iodine-131
Xenon-131
Hydrogen-2
Uranium-235
Hydrogen-1

6. Which ones are isotopes?
Uranium-238
Iodine-131
Xenon-131
Hydrogen-2
Uranium-235
Hydrogen-1

7. O O Review way to show atoms and ions
Shows atomic #, mass #, and neutrons
Preferred way
Mass # = _______
Atomic # = ______
Neutrons = _____
Electrons = _____
Protons = ______
Mass # = _______
Atomic # = ______
Neutrons = _____
Electrons = _____
Protons = ______ 16 17 O O 8 8

8. Radioactivity
Process by which an unstable nucleus emits one or more particles or wavelike high energy
Particles that are released from the nucleus during radioactive decay is called nuclear radiation.
There are different types of nuclear radiation
Alpha – 2 protons & 2 neutrons
Stopped with a piece of paper
Beta – electron
Stopped by aluminum shielding
Gamma – high energy waves
Stopped by thick layer of lead or concrete

9. Carbon-14 is used to date materials.
Radioactive Decay
Half-life
Time required for half of a sample of a radioactive substance to disintegrate by radioactive decay or by natural processes.
Half-life is a measure of how quickly a substance decays.
Using half-lives, scientist can predict how old an object is.
Carbon-14 is used to date materials.

11. Carbon-14 has a half-life of 6,000 years
Half-life Practice
Carbon-14 has a half-life of 6,000 years
If there is originally 100 atoms of carbon-14, how many are there after 6,000 years?
50 atoms
How about 12,000 years?
25 atoms
How about 18,000 years?
12-13 atoms

12. ET and Exam Review:

13. Radioactive materials have unstable
electrons.
b. protons.
c. nuclei.
d. neutrons.

14. After the nucleus of a radioactive element undergoes changes, the element can transform into a. a different isotope of the same element. b. an entirely different element. c. Both (a) and (b) d. Neither (a) nor (b)

15. The process of nuclear change in an atom of radioactive material is called
nuclear decay.
b. nuclear mass.
c. isotopes.
d. radon.

16. Atoms of the same element that have a different number of neutrons (and therefore mass) are called:
Ions
Isotopes
Antelopes
Anions