Half-Life Notes
I.
Isotope- an element with a different number of neutrons but same number of protons
a. Example
Hydrogen may have 0 Neutrons, 1 Neutron or 2 Neutrons
II.
Half Lifea. Measures the decay of atoms over time
b. Often the loss of neutrons from one isotope forming another isotope.
c. The time it takes for ½ of an original amount to decay
d. Questions: Answer the question below with help from your table.
1. If a sample has a half-life of 1 day, how much of sample will be left after…
a. 1 day?
b. 2 days?
c. 3 days?
Answers:
a. ½
b. ¼
c. 1/8
2. 100g of element X has a half-life of 10 yrs. How much will be left after…
a. 10 yrs.?
b. 100 yrs.?
Answers:
a. 50 g
b. .0977 g
e. Real World Application- Carbon dating
i. Carbon 14 decays and over time becomes Carbon 12
ii. Carbon 14 has a half life of 5730 yrs
iii. By measuring how much Carbon 14 is in an object you can tell how old it is.