Question

Amongst the elements $B,Al,C$ and $Si$, element having highest first ionization enthalpy is:

• A. $C$
• B. $Al$
• C. $B$
• D. $Si$

Answer 1

The correct option is A $C$

Ionisation enthalpy is defined as the amount of energy required to remove an outermost electron from an isolated gaseous atom. First I.E refers to the amount of energy needed to remove the first outermost electron.

Now along a period, nuclear charge increases by one unit so it will become more and more difficult to remove an outermost electron. So, I.E increases and along a group atomic size increases so it will become easier to remove the outermost electron so I.E decreases.

Among $B,Al,C,Si$; carbon will have the highest first I.E.