The Periodic Table


Organization and Features

Mendeleev organized the elements based on increasing atomic mass.

Moseley later organized by atomic number.

• Atomic number# of protons in an element

(equivalent to the # of electrons)

The periodic table is divided into 8 main groups not including the transition metals in the middle.

• Groups- vertical columns & contain elements with similar chemical properties.

Groups also have the same number of electrons in the outer shell.

 Valence Electrons

Some of these groups have special names based on the properties that they exhibit.

• Group 1 – Alkali metals

Group 2 – Alkaline Earth metals

Group 7 – Halogens

Group 8 – Noble Gases

 The noble gases are a group of very unreactive elements.

 Why do you think that we use Helium to inflate things?

 Has anyone ever heard of the Hindenburg?

Periods- Rows that go across the periodic table from left to right.

• As you move left to right on the periodic table, the atomic masses of the elements increases.

Atoms on the left of the period are usually larger and lighter than the smaller, heavier atoms on the right of the period.

The periodic tables contains a stair step line.

Separates elements as metals, nonmetals, and metalloids.


Show luster (shininess)

Good conductors of heat and electricity

High density

High melting point

Ductile-most metals can be drawn out into thin wires

Malleable- can be hammered into thin sheets


Easily lose their electrons

Corrode easily: a gradual wearing away

• Ie. Silver tarnishing or iron rusting


No luster- dull appearance

Poor conductors of heat and electricity

Brittle when solid-breaks easily

Not ductile

Not malleable

Low density

Low melting point


Tend to gain and share electrons


Can be shiny or dull



Conduct heat and electricity better than nonmetals but not as well as metals