The periodic table organizes all the elements according to their
chemical properties. The metals are located on the left side and
center of the table, and the non-metals are on the far right. In
between are the metalloids. One exception is hydrogen. It is a
non-metal, but it is located at the left side because it often
behaves like a metal in chemical reactions.
Period
Each horizontal line or row is called a Period. The
periods are numbered from 1 to 7. Hydrogen and helium
make up the first period.
Group or Family
Each vertical column forms a Group or Family of elements,
numbered from 1 to 18. Chemical families are groups of
elements that have similar chemical and physical properties.
Group 1: Alkali Metals
Group 1 is located in the column at the far left of the table, and
includes lithium, sodium, and potassium. Called the Alkali Metals,
they are all soft, shiny, and silver in color, and very reactive with
water. Their compounds tend to be white solids that are soluble in
water. Recall a compound is a chemical combination of two or
more elements in a specific ratio.
Group 2: Alkaline-Earth Metals
Group 2 includes magnesium and calcium. They are called the
Alkaline-Earth Metals. They are shiny and silver but are not as soft as
the Alkali Metals. Their compounds tend to be white, but they are
less soluble than compounds formed by the Alkali Metals.
Group 18: Noble Gases
Group 18 is the far right column containing helium, neon, and
argon. These are Noble Gases. They are very unreactive. Helium
has a very low density, which is why helium-filled balloons float,
and its non-reactivity means it cannot catch fire. Floating party
balloons are filled with helium.
Group 17: Halogens
The elements in group 17, just to the left of the noble gases, are called the
Halogens. This family of non-metals consists of the fluorine, chlorine, bromine, and
iodine. These elements are poisonous and react readily with the Alkali Metals to form
Salts, such as sodium chloride (table salt). Salts are compounds produced in
neutralization reactions between acids and bases.
The periodic table is organized into rows and columns.