Question

Identify the symbol for the missing element in each period.

C

O

F

Answer 1

Step 1: Find the period number

• The number of shells = period number.
• According to the question, all the elements represented belong to the same period.

Step 2: Finding the period number for one element

Carbon $\left(\mathrm{C}\right)$:

• The atomic number is $6$
• Electrons per shell $=2,4$
• The number of shells$=2$.
• So, the elements belong to period $2$.
• The elements belonging to period $2$ are Carbon $\left(\mathrm{C}\right)$, Nitrogen $\left(\mathrm{N}\right)$, Oxygen $\left(\mathrm{O}\right)$, Fluorine $\left(\mathrm{F}\right)$, etc.

Hence, the missing element is Nitrogen $\left(\mathrm{N}\right)$.