Exercises for Unit 2 on Atoms, Nuclei, Etc.

The following questions have been assigned for Unit 2:

1. How many protons, electrons and neutrons do the following atoms have:

Helium 4 (He 4): 2 protons, 2 electrons, 2 neutrons

Oxygen 18 (O 18): 8 protons, 8 electrons, 10 neutrons

Polonium 209 (Po 209): 84 protons, 84 electrons, 125 neutrons

Radon 222 (Rn 222): 86 protons, 86 electrons, 136 neutrons

What is the atomic number and mass number of Oxygen 18 and Radon 222?

The atomic number of O 18 is 8 and the mass number is 18. The atomic number of Rn 222 is 86 and the mass number is 222.

2. Thorium 232 (Th 232) undergoes alpha decay. What does an atom of Thorium 232 transform to when it decays?

Th 232 has 90 protons and 142 neutrons. It loses 2 protons and 2 neutrons to alpha decay so it winds up as Radium 228.

3. Oxygen 19 undergoes beta decay. What does an atom of Oxygen 19 transform to when it decays?

Since it's beta decay, add a proton to the atomic number and you have Fluorine 19 (F 19).

4. The extremely rare radioactive isotope Greensborium has a half-life of two years. If today you have one pound of Greensborium, how much of that Greensborium will you have in six years?

According to the lecture on scientific notation for this unit, after 3 half-lives you have 1/8 the original quantity. So, 2 oz.