Proton
A positively charged particle that is part of an atom's nucleus.
Neutron
A particle in the nucleus of the atom, with no electrical charge.
Electron
A tiny negatively charged particle that is found outside the nucleus of an atom
Nucleus
The central core of the atom, containing protons and usually neutrons.
Energy Level
A cloud outside the nucleus where electrons of the same energy are likely to be found.
Isotope
An atom with the same number of protons and a different number of neutrons from other atoms of the same element.
Atomic Number
The number of protons in the nucleus of an atom.
Atomic Mass
The average mass of all the isotopes of an element, weighted by their natural abundance.
Period
A horizontal row of elements in the periodic table. Represents an energy level.
Group
Elements in the same vertical column of the periodic table; also called a family. Have similar bonding properties.
Chemical Symbol
A one or two-letter representation of an element.
Reactivity
The ease and speed with which an element combines, or reacts, with other elements and compounds.
Alkali Metal
An element in Group 1 of the periodic table. Likes to lose an electron.
Alkaline Earth Metal
An element in Group 2 of the periodic table. Likes to lose two electrons.
Transition Metal
One of the elements in Groups 3 through 12 of the periodic table.
Diatomic Molecule
A molecule consisting of two atoms.ex: double molecule
Halogen
An element found in Group 17 of the periodic table. Likes to gain an electron.
Noble Gas
An element in Group 18 of the periodic table. Has complete energy levels. Nonreactive.