Question

Find the number of atom present in $PO_4^{3 - }$ ions $?$

Answer 1

First we know that a molecule is a group of two or more than two atoms of the same or different elements that are chemically bonded together. For example: Two atoms of hydrogen and one atom of oxygen react with each other and form one molecule of water. We need to find the number of atoms present in one molecule of a given compound.

Complete Step By Step Answer:
$PO_4^{3 - }$ - is a chemical derivative of phosphoric acid with the chemical name Phosphate. It is a trivalent inorganic anion and a conjugate base of hydrogen phosphate. It is composed of salts containing the phosphate ion, the dihydrogen phosphate ion, or the hydrogen phosphate ion. It is naturally found in food, human bodies, and water.
In a $PO_4^{3 - }$ -ion, one atom is of phosphorus, and four atoms are of oxygen.
Then,
Total number of atoms
$=$ Number of Oxygen atoms $+$ Number of Phosphorus atoms
$\Rightarrow = 4 + 1$
$\Rightarrow = 5$ atoms in one molecule of $PO_4^{3 - }$
Hence the number of atoms present in $PO_4^{3 - }$ ions are $5$ .

Additional Information:
To find the number of molecules in a substance, we need to determine the mass of the substance, and its molar mass. Then divide the given mass by its molar mass to get moles, then multiply times $\dfrac{{6.022 \times {{10}^3}molecules}}{{1\;mol}}$ we get number of molecules in a substance.

Note:
Phosphate is also called Phosphate ion or Orthophosphate. Also, the number of atoms of an element present in one molecule of that element is the atomicity of that element. Example, the atomicity of oxygen is $2$ because the number of atoms present in a molecule of oxygen are $2$ .