1. Put the letter of the correct answer in the blank. Recall that the / symbol means per and the symbol # means number. For example, # cents/dollar reads: number of cents per dollar.

Mass number _____

Atomic number _____

Isotopes of one element _____

Radioactive element _____

Periodic table _____

a) # protons/nucleus

b) # protons and neutrons/nucleus

c) # protons same, # neutrons differ

d) arranged by # protons/nucleus

e) nuclei break down

2. Find the chemical symbols and atomic numbers of these elements:

a) silver

b) arsenic

c) neon

d) tungsten

e) radon

3. The mass number of a uranium isotope is 238. How many protons, neutrons, and electrons in each atom?

4. An atom of a radioactive isotope of carbon changes by losing one proton. What "new" element is produced by this change?

5. If an atom of thorium loses 2 protons, what element would be left?

6. If a nitrogen nucleus gains 1 proton, what element would result?