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Unit 1B Honors
Ions, Valence Electrons, Reactivity 8th Grade Honors
Term | Definition |
---|---|
atomic number | the number of protons in the nucleus of one atom; identifies the element |
energy levels (shells) | the "layers" around the nucleus where electrons may be found; a state in which matter can exist with a certain amount of energy and distinct from other states with different amounts of energy. |
valence electrons | the electrons in the outermost energy level of an atom -- they influence how an element will react with other substances |
reactivity | rate (speed) at which a chemical substance tends to undergo a chemical reaction; determined mainly by valence electrons of the reacting substances |
outermost energy level | determines the chemical properties of the atom because of the "rule of 8"; also called the valence shell |
net charge | the sum of negative and positive charges within the atom |
ion | an atom after a loss or gain of electrons; it now has an overall net charge (positive or negative) |
metal | typically solid, shiny, malleable, and good conductors of heat and electricity |
nonmetal | typically not shiny, usually a gas or brittle solid, not malleable, and poor conductors of heat and electricity |
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 |
cation | an atom with a positive charge; it has lost one or more electrons |
anion | an atom with a negative charge; it has gained one or more electrons |
metalloid | elements that have some properties of both metals and nonmetals; located on the "steps" on the PTE |
isotope | a non-typical version of an atom that has a different number of neutrons and therefore a different mass |