Across
- 5. the element under hydrogen
- 7. discovered in 1898 chemical symbol
- 9. has 8 valence electrons
Down
- 1. has the secound smallest atomic number
- 2. horizonal on the periodic table
- 3. is the very first element of the periodic table
- 4. has 1 valence elctron
- 6. atomic symbol is B and its atomic number is 5
- 8. its atomic number is 10 it is a noble gas