Why is the formation of water a synthesis reaction?

Explanation:

A synthesis reaction: It is defined as a kind of reaction where one and more than one reactant attached and creates an individual product.

The formation of the water is an example of a synthesis reaction because here more than one reactants combine and create a single product (water). Water formation occurs when 2 hydrogens and an oxygen share electrons through covalent bonds.

2H + O > H2O.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.