Question

after the transfer of electrons, calcium becomes an ion with a charge of type here and oxygen becomes an ion with a charge of type here.

Explanation:

Step1: Recall calcium's valence electrons

Calcium has 2 valence electrons. It loses these 2 electrons to achieve a stable octet. When it loses 2 electrons, it forms a cation with a charge of +2.

Step2: Recall oxygen's valence electrons

Oxygen has 6 valence electrons. It gains 2 electrons to achieve a stable octet. When it gains 2 electrons, it forms an anion with a charge of - 2.

Answer:

+2; -2