Which condition must be met in order for an equation to be balanced? The elements in the reactants are the same as the elements in the products. There are fewer elements in the reactants than there are in the products. The number of atoms in the reactants is greater than the number of atoms in the products. The number of atoms in the reactants equals the number of atoms in the products.

The number of atoms in the reactants equals the number of atoms in the products.

Explanation:

In every chemical reaction equation there are two sides; the reactants sides and the products side. The reactants side shows the species that combine to form the products. On both sides of the reaction equation, chemical species are found to be composed of atoms.

The major principle in balancing of chemical reaction equations is that the number of atoms of each element in the reactants side must be equal to the number of atoms of the same element on the products side. Once this condition is achieved, we can now say that the chemical equation is balanced.

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8