Isotopes and Ions

What is the difference?

Some definitions

Ion - an atom or group of atoms that has a positive or negative charge

How does and atom become an Ion?

By gaining or losing electrons

Ions

Atoms or groups of atoms that have a positive or negative charge

Formed by gaining or losing electrons

Ions are NEVER formed by gaining or losing protons

Cations and Anions

Cation

Positive charge

Formed by the atom losing electrons

Metals form cations

Cations

Ca Ca2+ + 2e-

Anion

Negative charge

Formed by the atom gaining electrons

Non-metals form anions

Anions

O + 2e- O2-

How do we know what atoms form which ions?

Use the periodic table

Columns are called groups or families– The elements in the same group tend to

have the same chemical properties– Groups are referred to by the number over

the column

Groups

Group 1 = alkali metals

Group 2 = alkali earth metals

Group 7 = halogens

Group 8 = Noble gases

In between groups = transition metals

Why is it called the Periodic Table?

As the atomic numbers increase, every so often we come across an element that has the same chemical properites.

Give rise to the rows, that we call periods

The ions formed by selected members of groups 1, 2, 3, 6, and 7.

Metals, non-metals and metalloids

Metals = elements to the left of the stair step

Non-metals = elements to the right of the stair step

Metalloids = elements along the stair step

Properties of Metals

Efficiently conduct heat and electricity

Malleability = can be hammered into sheets

Ductility = can be pulled into wires

Luster = shiny appearance

Form cations (positive ions) by losing electrons

Non-Metals

Lack the properties of metals

Many are gases at earth’s normal temperatures

Show more variation in their properties than metals

Form anions (negatively charged ions) by gaining electrons

Metalloids

Also called semi-metals

Display properties of both metals and non-metals

Include silicon, germanium, arsenic, antimony and tellurium