A chemical compound is a chemical substance consisting of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. The ratio of each element is ...

The chemical formula of a covalent molecular substance gives the number of atoms per molecule. The formula of a covalent network or ionic compound gives the simplest ratio of atoms/ions in the ...

Chemical reactions make new chemicals. Atoms are rearranged during a chemical reaction, but the number of atoms does not change. Evidence of chemical reactions includes a large temperature change, ...

Want to learn more about this centerpiece of chemistry? Take your pick from this collection of links about elements and the periodic table! Build an element ball, solve periodic puzzles, and check out ...