Use periodic trends / diagonal relationship

Aluminium ($\mathrm{Al}$) lies in group 13 and period 3. In the periodic table, some elements show a diagonal relationship, where an element in period 2 resembles the element diagonally down-right in period 3.

Thus, $\mathrm{Be}$ and $\mathrm{Al}$ show similarity in several properties.

Compare electronegativity values

Approximate Pauling electronegativities are:

• $\mathrm{Be} \approx 1.5$
• $\mathrm{Al} \approx 1.5$
• $\mathrm{B} \approx 2.0$
• $\mathrm{C} \approx 2.5$
• $\mathrm{Li} \approx 1.0$

So, the electronegativity of aluminium is closest to that of beryllium.

Check options

• A: Beryllium — correct
• B: Carbon — too high
• C: Boron — higher than aluminium
• D: Lithium — lower than aluminium

Final answer

The correct option is: $\boxed{\text{A: Beryllium}}$

Comparison with stored answer

Stored correct answer = A, which matches the derived answer.