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Prentice Hall Science Explorer Chemical Building Blocks Chapter 3


an atom's central region, which is made up of protons and neutrons


a subatomic particle that has a positive charge and that is found in the nucleus of an atom


a subatomic particle that has no charge and that is found in the nucleus of an atom


negatively charged particle; located outside the atomic nucleus

atomic number

the number of protons in the nucleus of an atom


an atom that has the same number of protons (or the same atomic number) as other atoms of the same element do but that has a different number of neutrons (and thus a different atomic mass)

mass number

the sum of the number of neutrons and protons in an atomic nucleus


can be used to represent an idea, object, or event that is too big, too small, too complex, or too dangerous to observe or test directly

atomic mass

the average mass of all the isotopes of an element

periodic table

a tabular arrangement of the chemical elements according to atomic number as based on the periodic law

chemical symbol

a one or two letter representation of an element


a horizontal row of elements in the periodic table


Vertical column of elements in the periodic table


a class of elements characterized by physical properties that include shininess, malleability, ductility, and conductivity


can be bent and pounded into various shapes


Capable of being drawn out, as into wire or a thread.


the ability of an object to transfer heat or electricity to another object


the ease and speed with which an element combines, or reacts, with other elements and compounds


the gradual wearing away of a metal element due to a chemical reaction

alkali metal

an element in group 1 of the periodic table

alkaline earth metals

The name of the family of elements in Group 2.

transition metal

An element in group 3 through 12 of the periodic table


a mixture of two or more elements, one of which is a metal

particle accelerator

a machine that moves atomic nuclei at higher and higher speeds until they crash into one another, sometimes forming heavier elements


An element that lacks most of the properties of metals

diatomic molecule

a molecule consisting of two atoms


an element found in group 17 of the periodic table

noble gas

one of the elements of Group 18 of the periodic table (helium, neon, argon, krypton, xenon, and radon); are unreactive


an element that has some characteristics of metals and some characteristics of nonmetals


an element that can conduct electricity under some conditions

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