Across
- 4. ,side to side on the periodic table
- 6. ,most abundant metal in earth's crust
- 9. ,designed the periodic table of elements
- 10. ,two atoms with different number of neutrons
Down
- 1. ,a positively charged subatomic particle in the atomic nucleus
- 2. ,lightest alkali metal
- 3. ,up and down on the periodic table
- 5. ,an electron in the outermost energy level of an atom
- 7. ,number of protons
- 8. ,any material that is made up of only one type of atom