1. Explain why elements tend to form bonds in compounds and provide two examples of how they can do that. 2. Difference between polar and non-polar molecule.

1. Because they are unstable and can share electrons in their outer energy levels.

2. Polar molecules occur when there is an electronegativity difference between the bonded atoms. Nonpolar molecules occur when electrons are shared equal between atoms of a diatomic molecule or when polar bonds in a larger molecule cancel each other out.

A. mitochondrion b. nucleus