How do i know how many covalent bonds are made by each atom?

A covalent bond is a strong bond between two non-metal atoms. It consists of a shared pair of electrons. A covalent bond can be represented by a straight line or dot-and-cross diagram. Hydrogen and chlorine can each form one covalent bond, oxygen two bonds, nitrogen three, while carbon can form four bonds.

14,16 18 reacts with group

the ozone layer acts as a filter for the shorter wavelength and highly hazardous ultraviolet radiation (uvr) from the sun, protecting life on earth from its potentially harmful effects. when the sky is clear, there is an inverse relationship between stratospheric ozone and solar uvr measured at the earth's surface.