in alphabetical order

in the order in which they were discovered

 in order of increasing atomic number

 in order of increasing melting points

groups

periods

valences

isotopes

alkali metsls

transition metals

halogens

noble gases

 it reminds them what the elements look like

it can be used to predict how they react

 it lists the chemical formulas for all of the different compounds

 it contains the recipes for a variety of different kinds of mixtures

combines easily with other elements

is a solid at room temperature

 has atoms that are the same size

has a unique set of properties