The Periodic Table



The Periodic Table organizes the elements according to their properties. One atom of each element is made up of protons, neutrons, and electrons. The number of electrons determines how an element reacts. The number of protons gives the element its identity. Look at the different groups for clues to how the elements will react.


Noble Gases usually do not react because they do not tend to gain or lose electrons.
Alkali and Alkaline Earth Metals are soft and melt at low temperatures. They react well with nonmetals because they can easily give up electrons to form ions.
Transition Metals can have a slight charge which lets them bond easily to nonmetals. Compounds with these elements tend to be colored and have interesting magnetic properties.
Halogens are very reactive nonmetals because they easily accept electrons from other elements.
Lanthanide Metals are highly reactive but their ability to gain or lose electrons varies according to each element’s size, so they are less reactive from left to right across the table.
Actinide Metals are radioactive because they do not have enough energy to hold the protons and neutrons together in the atom’s nucelus permanently. They are very reactive and can gain or lose different numbers of electrons in reactions.
Metals conduct heat and electricity and typically lose electrons in a reaction.
Semi-metals have properties between metals and nonmetals and can gain or lose different numbers of electrons in reactions.
Nonmetals do not conduct heat and electricity well and usually gain electrons in a reaction.

Element Properties

The chemical properties of the elements are typically presented in the following way:


Atomic Number is the number of protons in an element. The number of protons in the atom’s nucleus is what makes one element different from another.
Atomic Symbol is an abbreviation used to indicate a specific element. The symbols are often, but not always, based on the element’s name.
Atomic Mass is the average mass of all the electrons, protons and neutrons in an element.