Physical Science B Unit 3

atom

the smallest unit of matter that makes up everything

bond

a force that holds atoms together

chemical bond

the attraction that joins atoms in a substance

stable

not likely to change; balanced

valence electrons

electrons in the outer energy level of an atom

ionic bond

a bond where electrons are transferred from one atom to another

covalent bond

a bond where atoms share electrons

ion

an atom that has gained or lost electrons and has a charge

positive ion

an atom that lost electrons and has a positive charge

negative ion

an atom that gained electrons and has a negative charge

molecule

a group of atoms bonded together by sharing electrons

compound

a substance made of two or more different elements bonded together

Lewis structure

a diagram that shows valence electrons as dots

electron dot diagram

another name for a Lewis structure

polarity

when electrons are shared unequally in a bond

polar molecule

a molecule with uneven charge distribution

nonpolar molecule

a molecule with equal sharing of electrons

metal

an element that tends to lose electrons and form positive ions

nonmetal

an element that tends to gain or share electrons

crystal

a solid with a repeating pattern of particles

melting point

the temperature at which a solid becomes a liquid

ionic compound

a compound made of ions held together by ionic bonds

molecular substance

a substance made of molecules with covalent bonds