Across
- 4. this 1A element would be the least reactive
- 5. the smallest atom
- 6. there are seven of these on the periodic table
- 10. the force of attraction between protons and electrons in an atom
- 13. this atom has only one ionization energy
- 16. all of these elements are soft and react vigorously with water
- 18. elements with the highest melting points and the best conductors
- 19. the measurement of the size of an atom
- 20. the only elements with full energy levels
Down
- 1. periodic law is based on increasing atomic number
- 2. ability of an atom to attract electrons towards its nucleus
- 3. the most reactive nonmetal
- 7. periodic law that was developed by Mendeleev
- 8. elements that tarnish easily in air and whose electrons fill the 4f sublevel
- 9. all of these elements are radioactive
- 11. the energy required to remove a valence electron from an atom
- 12. when core electrons block the attraction of the valence electrons
- 14. what comes out when elements are shot with cathode rays
- 15. the most reactive of all the nonmetals
- 17. C to Fl make one of these