Isotopes, Radioactivity, Decay

Review Atomic Structure

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)

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

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

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

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

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

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.

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

ET and Exam Review:

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

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)

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

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