Question

Drinking water may contain dissolved calcium hydrogen-carbonate,$Ca{\left( {HC{O_3}} \right)_2}$. How many electrons are present in a hydrogen-carbonate anion?

Answer 1

As we know that in chemistry, periodic tables play a vital role. In the periodic table there are totally $118$ elements. In the periodic table there are totally $18$ columns and $7$ rows. The columns are called groups. Hence, $18$ groups in the periodic table. The rows are called periods. Hence, totally $7$ period in the table.
Formula used:
The total number of electrons in the molecules or ions is dependent on the electrons in the atoms in the molecules or ions.
The total number of electrons in the molecules or ions is equal to the sum of the electrons in the atoms in the molecules or ions.

Complete answer:
The molecular formula of hydrogen-carbonate anion is $HC{O_3}^ -$
The atomic symbol of carbon is $C$. The atomic symbol of oxygen is $O$. The atomic symbol of hydrogen is $H$.
The atomic number of carbon atoms is $6$. The atomic number of oxygen is $8$. The atomic number of hydrogen atoms is $1$.
The number of electrons in the oxygen atom is eight and the number of electrons in the carbon atom is four and the number of electrons in the hydrogen atom is one.
In hydrogen-carbonate anion, one carbon atom and one hydrogen atom and three oxygen atoms and extra one electron from outside.
The total number of electrons is equal to the sum of the electrons in the atoms in the molecules or ions.
The total number of electrons on a hydrogen-carbonate anion $HC{O_3}^ -$ is calculated,
$= 6 + \left( {8 \times 3} \right) + 1 + 1$
$= 6 + 24 + 2 = 32$
The total number of electrons on a hydrogen-carbonate anion $HC{O_3}^ -$ is $32$ electrons.
According to the above discussion and calculation we conclude the total number of electrons on a hydrogen-carbonate anion $HC{O_3}^ -$ is $32$ electrons.

Note:
We have to know that the atomic number of the element is nothing but the number of electrons or number of protons. The mass number of the atom is nothing but the sum of the number of protons and number of neutrons. In every atom the number of protons and the number of electrons are equal. The stable electronic configuration in the second period is $10$. The stable electronic configuration in the third period is $18$.