A. An element is a pure substance that consists entirely of one type of atom

A. Periods(Horizontal rows): Number of electron increase by one as you move from left to right across

B. Families: (vertical rows) these atoms share the same chemical properties since they have the same amount of valence electronsEx. Li & Na

Element Families A. Noble Gases: all have 8 electrons in

its outer electron level, These are very stable elements, they do not combine easily with other elements. Group 18Uses: lightbulbs, neon lights are stable when an electric current is passed (not light hydrogen) 

B. Halogens: outer electron energy level has 7 electrons, if they gain 1 electron they become stable so these elements are very reactive (it wants to go out and party). Fluorine is the most reactive element in Group 17 

C. Alkali Metals: have 1 electron in its outer energy level, when these elements react this one electron is removed. Elements at the bottom are more reactive since there electron is more easily removed than the ones closer to the nucleus

Low melting point

a group of chemical elements in the periodic table with very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure

readily lose their two outermost electrons to form cations with charge +2

Do not occur naturally Less reactive Group 2

A metalloid is a chemical element with properties that are in-between or a mixture of those of metals and nonmetals, and which is considered to be difficult to classify unambiguously as either a metal or a nonmetal.