sodium reacts with oxygen to give sodium oxide using dots and crosses to represent electrons show bonding of sodium oxide

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.

Heat is involved in chemical change in two ways; chemical changes either result in heat being added to or removed from an object, and chemical changes require a certain amount of heat before they can take place.

In any atom of any element, you will find protons and neutrons in the nucleus of any atom 

Answer it was we, the the whole people, who formed the union. and we formed it, not to give the blessings of liberty, but to secure them: not to the half of ourselves and the half of our posterity, but to the whole people- women as well as men.