1. Isotopes

2. Fukushima disaster May 11, 2011
Fukushima nuclear power plant damaged by tsunami

11. Chernobyl Disaster April 26, 1986
Melt down inside the reactor in Unit #4 of the Chernobyl Nuclear Power Plant
The steam explosion and fire blew the 1000-ton roof off the building and allowed radioactive material to escape (Cs-137, I-131, and Sr-90)

12. Thyroid cancer
Radioactive iodine deposited in pastures  eaten by cows  cow milk drunk by children
Radioactive iodine to accumulated in the thyroid
Thyroid produces hormones that regulate your heart rate, blood pressure, body temperature and weight

13. Nuclear power Nuclear fission = Process of splitting atoms
Fission produces free neutrons and protons and release large amount of energy
Marble demo

14. Isotopes
Isotopes = have nucleus with the same number of protons but different number of neutrons
Therefore, isotopes have different mass numbers
Unstable atoms are radioactive, nucleus can decay or change by emitting radiation

15. Average atomic mass
Average atomic mass of an atom is found by averaging the natural abundance of its isotopes
E.g. 35/17 Cl (75%) and 37/17 Cl (25%)
(0.75 x 35) + (0.25 x 37) = 35.5 amu