How the elements are formed?
Elements are identified by the nuclei of the atoms of which they are made. For example, an atom having six protons in its nucleus is carbon, and one having 26 protons is iron. ... Heavy elements can be formed from light ones by nuclear fusion reactions; these are nuclear reactions in which atomic nuclei merge together.
How do we know what elements are?
Explanation: There are two properties that can be used to identify an element: the atomic number or the number of protons in an atom. The number of neutrons and number of electrons are frequently equal to the number of protons, but can vary depending on the atom in question.