8 TH GRADE VOCABULARY M.ESPINDOLA-MORENO

ATOM The smallest particle of an element made of electrons, protons, and neutrons.

PROTON A positively charged subatomic particle of the nucleus of an atom that contributes to the mass of the atom.

ELECTRON A negatively charged subatomic particle that orbits the atomic nucleus.

NEUTRON A subatomic particle of the nucleus of an atom without a charge that contributes to the mass of an atom. Neutron

ELECTRON CLOUD The area surrounding the nucleus of an atom where the electrons are found.

ELECTRICAL CHARGES A property of matter; Electrons are negative Protons are positive Neutrons are neutral The # of Protons and Electrons determine the charge of the atom.

ATOMIC MASS The mass of an atom, equal to the # of protons and neutrons in the atom.

SUBATOMIC PARTICLES Particles that are smaller than the atom Protons Neutrons Electrons

ATOMIC NUMBER The number of protons in the nucleus of an atom.

ENERGY LEVEL The fixed amount of energy that a system described by quantum mechanics, such as a molecule, atom, electron, or nucleus, can have.

VALENCE ELECTRON The electrons in the outermost energy level of an atom that influence how an element will react with other substances.

REACTIVITY Rate at which a chemical substance tends to undergo a chemical reaction.

PERIODS Rows on the periodic table Read from left to right. There are 7 periods.

GROUPS Columns on the periodic table. Read from top to bottom, There are 18 groups.

ALKALI METALS Most reactive metals on periodic table. 1 valence electron Soft and shiny

AKALINE EARTH METALS Group 2 Hard metals 2 valence electrons

HALOGENS Group 17 7 valence electrons Very reactive nonmetals

NOBLE GASES

METALS, NONMETALS, METALLOIDS

ELEMENT An element is a pure substance that cannot be separated into simpler substances by chemical means.

COMPOUND When two or more elements combine chemically.

ORGANIC COMPOUNDS Organic compounds contain carbon…

SUBSCRIPT A # written below and to the right of an atomic symbol.

COEFFICIENT A # placed in front of a chemical symbol or formula.

CHEMICAL FORMULA A shorthand notation using chemical symbols and numbers.