8. Give the symbol of and the number of neutrons in one atom of: (Round the MASS numbers so they are ALWAYS whole numbers…show your calculations)
Beryllium
Calcium
Sulfur

Explanation:

Given species;

  Beryllium

  Calcium

   Sulfur

Unknown:

Give the symbol, number of neutrons and the mass number

Solution:

The symbols of the species are;

    Beryllium  -   Be

    Calcium     -  Ca

     Sulfur       -  S

Number of neutrons:

    Beryllium - 5

   Calcium    - 20

   Sulfur       -  16

Mass number :

  Beryllium - 9

    Calcium - 40

     Sulfur -    32

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.