Explain the reason for classifying the periodic table into blocks

The long form of the periodic table divides the elements into four major blocks known as s, p, d, and f.

The period to which a given element belongs can easily be determined from its electron configuration. Based on electron configurations, the periodic table can be divided into blocks denoting which sublevel is in the process of being filled.

Hope it helps.

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

if you need further assistance, let me know: )

~ trueboss72