Compounds and Bonding

Introduction to Ionic Bonding

The Periodic Table

First a review of the

Elements are arranged by atomic number

Vertically

into Groups

Horizontally Into Periods

Draw electron configuration diagrams to show the electron arrangements for these elements on the periodic table provided

remember 2,8,8,2

Do this for the first twenty

elements before the next slide.

Make a conclusion: Look at the diagrams you drew for each group . . .

Each atom has the same number of electrons in it’s outermost

shell.

These electrons are called valence electrons. Valence electrons determine how an element will form chemical

bonds and react.

For example - the Group 2 elements all have 2 valence electrons.

Be (Beryllium)

AtomMg (Magnesium)

Atom

• The number of outer or “valence” electrons in an atom effects the way an atom bonds.

• The way an atom bonds determines many properties of the element.

• This is why elements within a group usually have similar chemical properties.

For example alkali (group 1) metals all react with water to produce hydrogen gas

If you looked at an atom from each element in a period

What do you see…

Each atom has the same number of electron holding

shells.

For example: the period 4 atoms each have 4 electron shells

K (Potassium)

Atom Fe (Iron) Atom

Kr (Krypton)

Atom

4

Now, use a different color and write the 2,8,8,2 electron arrangements for the first 20 elements on your handout.

1 2

2,1 2,2 2,3 2,4 2,82,72,62,5

2,8,1 2,8,2 2,8,3 2,8,4 2,8,82,8,72,8,62,8,5

2,8,8,1 2,8,8,2

What do you observe?

The last number in the electron arrangement indicates the number of valence electrons. This is the same

for all elements in a group.

Other useful things to know about the Periodic Table

Solids, liquids and gases (at room temperature)

Metals, metalloids and non-metals

Alkali Metals

Soft, silvery colored metals

Very reactive!!!

Alkaline Earth Metals

Silvery-White Metals

Fairly reactive

Many are found in rocks in the earth’s

crust

Transition Metals

Malleable (easily bent/hammered

into wires or sheets)

Most are good Conductors of

electricity

Poisonous

Reactive

Halogens

Unreactive

Mono-atomic

Gases at room temperature

Noble Gases