Q1: (a) Write the electron dot structure of Ca (At. No. 20) and O (At. No. 8). (b) Show the formation of calcium oxide by the transfer of electrons. (c) Name the ions present in this compound. (d) List four important characteristics of this compound.

(a) The electron dot structure, also known as Lewis dot structure, represents the valence electrons of an atom.

• For Calcium (Ca), atomic number 20, the electron configuration is 2, 8, 8, 2. So, the electron dot structure will have two dots representing the two valence electrons.

• For Oxygen (O), atomic number 8, the electron configuration is 2, 6. So, the electron dot structure will have six dots representing the six valence electrons.

(b) The formation of calcium oxide (CaO) involves the transfer of electrons from calcium to oxygen. Calcium, having two valence electrons, loses these two electrons to achieve a stable electron configuration. Oxygen, having six valence electrons, gains these two electrons to achieve a stable electron configuration. This transfer of electrons results in the formation of calcium oxide.

(c) The ions present in this compound are Calcium ions (Ca2+) and Oxide ions (O2-).

(d) Four important characteristics of calcium oxide are:

1. It is a white, crystalline solid at room temperature.
2. It has a high melting point (2572°C).
3. It is a basic oxide and reacts with water to form calcium hydroxide.
4. It is used in various industrial applications such as the manufacture of cement, glass, and ceramics.