Covalent bonds are in the air you breathe and the water you drink. how are covalent bonds formed?

Covalent bond is the term that is being used to describe the bonds in the compounds that are created due to the sharing of one or more electrons. One of the best example of the simplest covalent bond is the bond that is being created when two isolated hydrogen atoms come together to form an H2 molecule. An isolated hydrogen atom has one proton and electron being combined by the force of attraction from the opposite-charged articles. When a pair of isolated hydrogen atom combines, two forces of attraction are created coming from each of the isolated hydrogen atom.

☆ionisation energy increases across a period from na -> ar☆ionisation energy decreases down a group from li -> fr☆ionic radius decreases across a period from na -> cl☆ionic radius increases down a groupfrom f -> ii hope it clarifies your doubts