Across
- 4. much larger and heavier than electrons they also have a positive charge
- 6. two atoms with different numbers of neutrons are called
- 7. large and heavy and have no electrical charge
- 8. average mass of the naturally occurring isotopes of an element
- 9. equal to the number of protons plus neutrons
- 10. tiny and light particles that have a negative electrical charge
Down
- 1. they are often used for things that are too small or too large to be observed
- 2. any of the possible energies an electron may have in an atom
- 3. what is the number of protons
- 5. also called the wave model