An electron is a subatomic particle that orbits the nucleus of an atom. It carries a negative electric charge. Generally, an atom has the same number of negative electrons orbiting the nucleus as it does positive protons inside.

A compound is a substance containing two or more different chemical elements bound together by a chemical bond. In covalent compounds, electrons are shared between atoms. In ionic compounds, one atom borrows an electron from another atom resulting in two ions (electrically charged atoms) of opposite polarities that then become bonded electrostatically.

Primary consumers (herbivores) subsist on producers like plants and fungus.  Examples are grasshoppers, cows, and plankton.

A substance undergoes a phase transition when it moves from one state of matter to another, for example, when water freezes or boils.

To convert from C° to F° use:

\(F° = {9 \over 5}C° + 32\)

\(F° = {9 \over 5}(0) + 32\)

\(F° = 0 + 32 = 32\)