Writing Formulas and Naming Compounds

criss-cross method
numerical value of the charge of earch ion is crossed over and becomes the subscript for the other ion

ionic compound
a compound composed of positive and negative ions

ion
an atom or group of atoms that has a positive or negative charge

monoatomic ion
a single atom with a postitive or negative chare resulting from the loss or gain of one or more valence electrons

polyatomic ion
a tightly bound group of atoms that behaves as a unit and has a positive or negative charge

cation
any atom or group of atoms with a positive charge

anion
any atom or group of atoms with a negative charge

molecular formula
a chemical formula of a molecular compound that shows the number and kinds of atoms present in a molecule of a compound

chemical formula
an expression that indicates the number and type of elements present in the smallest representative unit of a substance

molecular compound
a compound that is composed of molecules