Which of the following pairs are chemically dissimilar?
Ca, Cu
The electronic configuration of the elements reflects their chemical properties.
The electronic configuration of calcium is 2,8,8,2 and that of copper is 2,8,18,1. Since the electronic configurations of Ca and Cu are different, they are chemically dissimilar.
The electronic configuration of sodium is 2,8,1 and that of potassium is 2,8,8,1. Since the number of valence electrons of Na and K is the same, they are chemically similar.
The electronic configuration of boron is 2,3 and aluminium is 2,8,3. Since the number of valence electrons of B and Al is the same, they are chemically similar.
The electronic configuration of beryllium is 2,2 and that of magnesium is 2,8,2. Since the number of valence electrons of Be and Mg is the same, they are chemically similar.