Atoms and Bonding Chapter 6.1 cont...

Compounds and Bonding A compound is a substance that is composed of atoms of two or more different elements that are chemically combined.

Why do Atoms Combine? Atoms combine with other atoms only when the resulting compound is more stable than the individual atoms. For many elements, an atom becomes stable when its outermost energy level is full having 8 electrons. 3 types of bonds that form between atoms.

1. Covalent Bonds A covalent bond is a force that holds or bonds two atoms together. Covalent bonds form by sharing electrons. A molecule is a group of atoms held together by covalent bonds. It has no overall charge.

Covalent Bonds Ex: 2 H (hydrogen) atoms can combine with each other by sharing their electrons. Each atom becomes stable by sharing its electron with the other atom. Now each H atom has 2e- in its energy level. Hydrogen molecule e-

2. Hydrogen Bonds - Water Weak bond that forms between polar molecules, like water are called hydrogen bonds.

3. Ionic Bonds Atoms can also combine by gaining or loosing an e- (electron). Ion = an atom that has lost or gain an e- - it has a charge (-) or (+) - NaCl (salt) is held together by an ionic bond. Ionic bond = the attractive force between two ions of opposite charge.

Chemical Reactions