Across
- 1. shiny solids
- 6. no electrical charge
- 7. dense core of an atom
- 8. carries a negative charge
- 9. sum of the number of protons and neutrons in the nucleus
- 11. the horizontal row in the periodic table
Down
- 2. the simplest type , composed of only one atom
- 3. each vertical column on the periodic table
- 4. electrons in the outermost energy levels
- 5. has a positive charge
- 6. helium, neon, argon, krypton, xenon, and radon
- 10. two or more substances are physically mixed, but not chemically combined