A repeating trend in properties of the elements across each period of the periodic table.
Proton number
The number of protons in the nucleus of an atom, also known as atomic number.
Group
A vertical column in the periodic table. Elements in a group have similar chemical properties and their atoms have the same number of outer shell electrons
across period 2 and 3
melting point increases from Group 1 to Group 14 (4)
there is a sharp decrease in melting point between Group 14 (4) and Group 15 (5)
the melting points are comparatively low from Group 15 (5) to Group 18 (0)
Giant metallic structures in period 2:
Li
Be
Giant metallic structures in period 3:
Na
Mg
Al
Giant covalent structures in period 2:
B
C
Giant covalent structure in period 3:
Si
N2, O2, F2 and Ne are simple molecular structures
P4, S8, Cl2 and Ar are simple molecular structures
