Atoms are held together by bonds. There are several varieties of bonds. In the IONIC bond one aton steals an electron from another atom. The stealer becomes negatively charged (because of its extra electron) and the stealee becomes positively charged. Opposites attract and the stick together, or bond. In the COVALENT bond adjacent atoms share electrons and bond. The HYDROGEN bond is a weak bond due to one side of a molecule being slightly charged due to an uneven distribution of charge within the molecule (even though the molecule in, on the whole, neutral).