First 264 words of the document:
Atoms are made up of three particles. Electrons, protons and neutrons. Neutrons and
protons are found together in the nucleus and are together known as nucleons.
Electrons orbit the nucleus, much like the earth orbits the sun.
Protons +1 charge Weigh 1 unit
Neutrons 0 charge Weigh 1 unit
Electrons -1 charge Negligible
The number of protons is the atomic number of an atom.
The number of protons and neutrons combined within a nucleus is called the mass
Some atoms have the same atomic numbers but different mass numbers aka a
different number of neutrons, are known as isotopes.
Atoms are usually stable, this means they are of a neutral charge, ions however, are
The relative atomic mass of an atom is the ratio of the average mass of one atom of
that element to 1/12th of the mass of one atom of carbon-12.The relative isotopic mass
of an isotope is the ratio of the mass of one atom of that isotope to 1/12th of the mass
of one atom of carbon-12.
Basically, it is the mass number of a simple atom. In isotopes, it is the average of the
The relative molecular mass of a molecule is the ratio of the average mass of that
molecule to 1/12th of the mass of an atom of carbon-12.
Essentially, this is the number given when the RAM of each element in a compound
is added up.