The Periodic Table

The Periodic Table

is a chart that organizes all the elements in a way that shows patterns – both similarities and differences among the elements.

Elements are listed by increasing atomic number.

The horizontal rows are called periods. There are 7 periods.

The vertical columns are called groups. There are 18 groups.Elements in the same group have similar

chemical properties.

Periods

Each period corresponds to the energy levels found outside an atoms nucleus

The period that an element is located in tells you what the highest energy level is that will contain electrons

PeriodsThe most energy levels found in an atom (currently) is seven which corresponds to the seven periods in the table

Example Potassium (K) is located in period 4 and thus will

have its valence electrons in the fourth energy level

Period 1

Period 2

Period 3

Group 1

Group 2

3 4 5

18

Period 7

Special GroupsGroup 1 elements are known as the alkali metals.

Group 2 elements are known as the alkaline earth metals.

Group 17 elements are called halogens.

Group 18 elements are called noble gases.

Groups 3-12 are called transition metals.

The Lanthanides and Actinides are the excerpts at the bottom.

Group 1 – Alkali MetalsHave only one e- in the valence shell

Most reactive of all metals – reactivity increases as you go down the group

Hydrogen is an exception!Has one valence electron

but is classified as a non-metal

Group 2 – Alkaline Earth Metals

Has two e- in valence shell

Become increasingly soluble with increase in temperature

Group 18 – Noble Gases

Generally are chemically inert meaning they do not react with other elements

This is because they already have 8e- in their valence shell causing them to be stable

(He only has 2 valence e-)

Only He and Ne are truly inert – others will react in limited amounts under specific conditions

Group 17 – HalogensHalogen means “salt former” – form salts when reacting with a metal

Most exist as diatomic molecules in gaseous state

Ex. Cl2

All are one e- short of a full valence shell causing them to be very reactive

Are non-metals

Transition and Rare Earth MetalsSome of the rest of the elements in the periodic table fall under these two categoriesTransition metals are groups 3 – 12Rare earth (inner transition) metals are broken

down further into actinides and lanthanides

Transition and Rare Earth Metals

These are also called the inner transition elements and they

belong here

These are also called the inner transition elements and they

belong here

Groups 1, 2 (s block) and 13-18 (p block) are often called representative elements. They are sometimes labelled 1A, 2A, 3A, …8A

Representative Elements

1A

2A 3A 4A 5A 6A7A

8A0

These elements are called the representative elements

The Periodic Table

There are 3 major sections of elements in the periodic table:

1. Metals2. Non-metals3. Metalloids

Metals are located to the left of the “staircase line” and non-metals are to the right (except H). Metalloids border the line.

Properties of Metals

Physical Properties Luster (shiny) Good conductors High density High melting point Malleable/bendable Solid at room

temperature (except Hg)

Chemical Properties:

Easily lose electrons Corrode easily (ex:

rusting or tarnishing) Low electronegativity

Properties of Non-metals

Physical Properties: Dull Poor conductor Brittle Not malleable Low density and melting point

• Chemical Property: Tend to gain electrons High electronegativity

Properties of MetalloidsMetalloids border the “staircase” and tend to have some properties of both metals and non-metals.

solids

can lose or gain electrons

semi-conductors of electricity (Conduct heat and electricity better than non metal but not as well as metals

Shiny or dull

Malleable

The Periodic Table