"Periodicity Crossword": HTML5 Crossword

Across

2. s for .................... (5)
4. Has a melting point of 84 K (5)
5. The most commonly measured type of radius (8)
6. Contract across a period (5)
7. [Ne] 3s2 3p3 (11)
10. The Russian (9)
12. These tend to be more electronegative than the other elements (9)
14. Lanthanides & Actinides Block (11)
15. Groups 1 - 4 tend to have these structures (5)
18. Separates the metals from non-metals (9)
19. d for ..................... (7)
20. Discovered the Nobel gases single-handedly ! (6)

Down

1. Block containing the 'staircase' (9)
3. Carbon forms these (14)
8. The state required for ionisation (7)
9. The electrons in metals (11)
11. The most common type of element (6)
13. Highest melting point in period 3 (7)
16. Another word for periods (4)
17. Columns (6)