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The Periodic Table: Elements and Compounds
Vocabulary
Periodic table: A chart in which elements are arranged by increasing atomic
number and by changes in physical and chemical properties.
atom: The smallest particles that make up matter.
proton: a subatomic particle that has a positive charge and that is located in the
nucleus of an atom. (The number of protons in the nucleus is the atomic number,
which determines the identity of an element.)
neutron: a subatomic particle that has no charge and that is located in the nucleus of
an atom.
electron: a subatomic particle that has a negative charge.
element: a substance that cannot be separated or broken down into simpler
substances by chemical means.
compound: a substance made up of atoms of two ore more different elements joined
by chemical bonds.
atomic number: the number of protons in the nucleus of an atom. (The atomic
number is the same for all atoms of an element.)
chemical symbol: a one, two, or three-letter abbreviation of the name of an element
on the periodic table.
Molecule: A particle made up of two or more atoms bonded together.
Metal: An element that is typically a hard, shiny solid, is malleable, and is a good
conductor of heat and electricity
Metalloid: An element that shares some properties of metals and some of nonmetals
Nonmetal: An element that is usually a gas or brittle solid at room temperature,
is not malleable or ductile, is a poor conductor of heat and electricity, and is
typically not shiny