As the elements in period 3 are considered in order from sodium to chlorine, there is an increase in the

1) atomic radius

2) electronegativity

3) number of electrons in the first shell

4) number of electron shells

2 Electronegativity

Explanation:

Period 3 on the element table contains the following eight elements

Element Symbol Atomic number Atomic radius / nm

sodium Na 11 0.191

magnesium Mg 12 0.160

aluminium Al 13 0.130

silicon Si 14 0.118

phosphorus P 15 0.110

sulfur S 16 0.102

chlorine Cl 17 0.099

argon Ar 18 0.095

Sodium and magnesium, are members of the s-block of the periodic table

The rest are members of the p-block.

In the whole of period 3, the outer electrons are all in 3-level orbitals

Na [Ne] 3s1

Mg [Ne] 3s2

Al [Ne] 3s2 3px1

Si [Ne] 3s2 3px1 3py1

P [Ne] 3s2 3px1 3py1 3pz1

S [Ne] 3s2 3px2 3py1 3pz1

Cl [Ne] 3s2 3px2 3py2 3pz1

Ar [Ne] 3s2 3px2 3py2 3pz2

1) No

2) Yes

3) No

4) No