Question

Name an alkali metal in period $3$ and halogen in period $2$.

Answer 1

The chemical elements are arranged in periods and groups. The chemical elements present in the first group are known as alkali metals. The chemical elements present in the group $17$ are called halogens. Sodium is the element belonging to period $3$ and fluorine belongs to period $2$.

Complete answer:
Periodic table is the representation of chemical elements arranged in the increasing order of atomic numbers. Periodic table consists of a total of $118$ elements. These elements are arranged in the vertical columns and horizontal rows. The vertical columns were known as groups and the horizontal rows are known as periods. There are a total of $18$ groups and $7$ periods in the periodic table.
The chemical elements present in the first group are known as alkali metals. The chemical elements present in the group $17$ are called halogens.
Sodium is the element with atomic number $11$ and belongs to period $3$ and alkali metals. It is a metal as it has only one electron in its outermost shell and can easily lose this electron.
Fluorine is the element with atomic number $11$ and belongs to period $2$ and is a halogen. Halogen means salt formers as these elements form salts with alkali metals.

Note:
Alkali metals are metals as they lose electrons easily and can be considered as metallic. Halogens are non-metals as they will try to gain electrons to attain the nearest noble or inert gas configuration. Halogens and alkali metals react with each other and form salts.