Across
periods 2 and 3, the melting point increases from
groups 1 to 14 (4) then there is a sharp decrease in melting point between group 4 and 5. The melting point of groups 5 to group 8 are lower than those in the first four groups.
The elements in groups 1 to 4 have giant structures. The elements in groups 5 to 7 have simple molecular structures and group 8 elements exist as single atoms.
Giant structures are held together by strong metallic, covalent or ionic bonds and need a lot of energy to break these bonds. Simple molecules have weak intermolecular bonds between them. Less energy is needed to overcome these forces so they have much lower melting points.
Period 2 Melting Points (K):
| Li | Be | B | C | N | O | F | Ne |
| 454 | 1560 | 2348 | 3823 | 63 | 54 | 53.5 | 24.5 |