Ions & Isotopes

1. Isotopes and Ions
What is the difference?

2. Some definitions
Isotope - atoms with the same number
of protons (same element) but with
different numbers of neutrons (different
mass)
Ion - an atom or group of atoms that
has a positive or negative charge

3. How does and atom become
an Ion?
By gaining or losing electrons

4. 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

5. Cation
Positive charge
Formed by the atom losing electrons
Metals form cations

6. Cations
Ca Ca
2+
+ 2e
-

7. Anion
Negative charge
Formed by the atom gaining electrons
Non-metals form anions

8. Anions
O + 2e
-
O
2-

9. 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

10. Groups
Group 1 = alkali metals
Group 2 = alkali earth metals
Group 7 = halogens
Group 8 = Noble gases
In between groups = transition metals

11. 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

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

13. 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

14. 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

15. 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

16. Metalloids
Also called semi-metals
Display properties of both metals and
non-metals
Include silicon, germanium, arsenic,
antimony and tellurium