Question

Consider the group 1A element sodium (atomic number 11), the group 3A element aluminum (atomic number 13), and the group 7A element chlorine (atomic number 17). These elements are in period 3. How are the first ionization energies of these elements related?

Answer 1

sodium<aluminum<chlorine

Answer 2

The first ionization energy will increase from sodium to aluminium to chlorine (on moving from left to right in the period).

Step-by-step explanation:

The ionization energy is the energy required to remove an electron from the valence shell of an isolated gaseous atom of an element.

Now the ionization energy depends upon

a) size of an element ,larger the size more lesser the effective nuclear charge on electron thus lower the ionization energy.

b) the electronic configuration of an element. If on losing an electron an element attains noble gas configuration or half filled stability then it will easily lose an electron.

In case of Sodium, if it loses an electron it will attain the noble gas configuration of Neon.

also the size of sodium is more than that of aluminium and the size of aluminium is more than that of chlorine.

So it is most easy to remove electron from sodium than from aluminium and than from chlorine.

Relation will be:

First ionization energy will increase as:

Na < Al < Cl