Question

Enter the number of electrons in each energy level (shell) for the following elements. He, F, Na, K, If the energy level does not contain any electrons, enter a 0 (zero). It may help to refer to the periodic table.

Answer 1

Step-by-step explanation:

Helium is the element of 18th group and first period. The electronic configuration of helium is - 2 or
`1s^2`

There are 2 valence electrons of helium.

Fluorine is the element of 17th group and second period. The electronic configuration of fluorine is - 2, 7 or
`1s^22s^22p^5`

There are 7 valence electrons of fluorine.

Sodium is the element of 1st group and third period. The electronic configuration of sodium is - 2, 8,1 or
`1s^22s^22p^63s^1`

There is 1 valence electron of sodium.

Potassium is the element of 1st group and forth period. The electronic configuration of potassium is - 2, 8, 8, 1 or
`1s^22s^22p^63s^23p^64s^1`

There is 1 valence electron of potassium.

Hence,

He: 2,0,0,0,0,0,0

F: 2,7,0,0,0,0,0

Na: 2,8.1,0,0,0,0

K: 2,8,8,1,0,0,0