AP BIOLOGY

Detailed explanation-1: -Strong linkages-called covalent bonds-hold together the hydrogen (white) and oxygen (red) atoms of individual H2O molecules. Covalent bonds occur when two atoms-in this case oxygen and hydrogen-share electrons with each other.

Detailed explanation-2: -For example, oxygen molecules consist of two oxygen atoms joined together. Oxygen atoms can form two covalent bonds, so to link the two oxygen atoms together, a double bond forms between them.

Detailed explanation-3: -The hydrogen molecule is the simplest substance having a covalent bond. It forms from two hydrogen atoms, each with one electron in a 1s orbital. Both hydrogen atoms share the two electrons in the covalent bond, and each acquires a helium-like electron configuration.