Atoms and Atomic Structure 

by Owen Borville
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An atom is the smallest unit of an element that has certain chemical properties.
An element is one specific type of atom that has certain chemical properties.
A compound is a substance containing two or more atoms chemically bonded together.
A molecule is the smallest unit of a compound that has defined chemical properties.
An ion is an atom or group of atoms bonded together that has an electric charge. Cations are positively charged ions and anions are negatively charged ions.
A proton is a positively charged sub-atomic particle located in the nucleus, or central portion of the atom.
A neutron is a subatomic particle with no charge that is located in the nucleus.
An electron is a negatively charged subatomic particle that orbits or rotates around the nucleus of the atom and has a mass much less than protons and neutrons. Atoms can have several electrons orbiting around the nucleus.
The Atomic Number is the number of protons in one atom.
The Atomic Mass Number is the number of protons and neutrons in an atom.
An isotope of an atom is an atom with same atomic number (protons) but different number of neutrons.