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26 terms

Key Chemistry Terms

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matter
anything that occupies space and has mass
element
a pure substance that cannot be broken down into other substances by chemical reactions
compound
substance containing two or more elements chemically combined in a fixed ratio
atom
the smallest particle of an element that retains the properties of the element
proton
subatomic particle having a positive charge; found in nucleus
electron
subatomic particle having a negative charge; not in nucleus but surrounds it
neutron
subatomic particle without a charge; found in nucleus
nucleus
protons and neutrons together; make up the center of an atom
atomic number
identifies a specific element; equals the number of protons in an atom of each element
radioactive isotope
an unstable atom in which the nucleus decays (breaks down) releasing particles and energy
isotope
atoms having the same numbers of protons but different numbers of neutrons
ionic bond
occurs when atoms transfer electrons to other atoms
ion
atoms that have lost or gained electrons
covalent bond
occurs when atoms share electrons
molecule
atoms that are held together by covalent bonds
chemical reaction
interaction of substances that lead to the formation of new substances
reactant
the starting materials for a reaction; found on left side of chemical equation
product
ending materials of a reaction; found on right side of chemical equation
organic compound
substance made of two or more elements, one being carbon
inorganic compound
substance made of two or more elements, none of which is carbon
valence electrons
electrons in the outermost energy level; they are involved in bond formation
single bond
a covalent bond in which one pair of electrons is shared
double bond
a covalent bond in which four valence electrons are shared between two atoms
chemical formula
indicates the number and types of atoms in a molecule
structural formula
shows the number and types of atoms in a molecule and how they are arranged
chemical reaction
indicates the formation of new substances from previous substances