The electronic configurations of elements are as- A = 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 B = 1s^2 2s^2 2p^6 3s^2 3p^5 Which of the following is formula of ionic compound that could be formed between these two elements A and B?

Step-by-step solution

Element A has the electronic configuration 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 . It has 2 valence electrons in its outermost shell, so it loses 2 electrons to achieve a stable noble gas configuration, forming the A ²⁺ ion. Element B has the electronic configuration 1s^2 2s^2 2p^6 3s^2 3p^5 . It has 7 valence electrons in its outermost shell, so it gains 1 electron to achieve a stable noble gas configuration, forming the B ⁻ ion. To form a neutral ionic compound, one A ²⁺ ion combines with two B ⁻ ions. The formula of the