3. Basic
What is ion?
An ion is a charged atom or molecule. It is charged when the number of
electrons isn’t equal with the number of protons in the atom or molecule
What is atom?
singe particle that cant be broken down by chemical reaction.
What is molecule?
atoms join together to form molecule, only
non metals can bond together to form
molecules in a chemical bond.
4. How did it become an
ion?
Metal atoms and non-metal atoms go in opposite
directions when they ionize:
Metal atoms lose the electron, or electrons, in their highest
energy level and become positively charged ions
Non-metal atoms gain an electron, or electrons, from
another atom to become negatively charged ions
The process of an atom becoming an ion is called
ionization.
5. Positive Ion (Cation)
=> Occurs when an atom loses an
electron (negative charge)
=> more protons than electrons.
Negative Ion (Anion)
=> Occurs when an atom gains an
electron (negative charge)
=> more electrons than protons.
7. HOW TO DETERMINE THE
CHARGE?
The number of charges on an ion formed by a metal is equal to
the group number of the metal
The number of charges on an ion formed by a non-metal is equal
to the group number minus eight
Hydrogen forms H+ ions
8. Group
1
Example
element
Charge
Symbol
Of
Ion
Group 2
Na
Mg
+1
+2
Group
3
Group 4
Al
Co
+3
Carbon &
Silicon in
group 4
usually
form
covalent
bond by
sharing
electron.
Group
5
Group
6
Group 7
Group 0
N
O
Cl
He
-1
Don’t
react
with
other
element
to form
ion
EXAMPLE
Na+ Mg2+ Al3+
Carbon &
Silicon in
group 4
usually
form
covalent
bond by
sharing
electron
-3
N3-
-2
O2-
Cl-
Don’t
react
with
other
element
to form
ion
9. Ionic Bond
When metals react with non-metals:
Electrons are transferred from the metal atoms to the nonmetal atoms, forming ions.
The resulting compound is called an ionic compound.
The metal atoms become positive ions and the non-metal
atoms become negative ions.
There is a strong force of attraction between these oppositely
charged ions, called an ionic bond
10. EXAMPLE
Na losing an electron &
Cl gaining an electron
Thus the Na becomes
Na+
The Cl becomes Cl-
11. Covalent Bond
O A covalent bond is a strong bond between two non-
metal atoms. It consists of a shared pair of electrons.
O Covalent bonds are strong - a lot of energy is needed to
break them
O Atoms may form multiple covalent bonds
O There is a quick way to work out how many covalent
bonds an element will form. The number of covalent
bonds is equal to:
8 - the group number
12.
13.
14. To see the number of Covalent bond
Hydrogen forms 1 covalent bond
The noble gases in group 0 don’t form any
15. Covalent bonds can be represented in
several different ways.
1.
Straight lines and models
2.
Double and triple bonds
3.
Dot and cross diagram
16. Straight and line models
• Straight lines are the most common way to represent covalent
bonds, with each line representing a shared pair of electrons.
17. Double and triple bonds
• Note that molecules can have a double covalent bond - meaning they have
two shared pairs of electrons - or a triple covalent bond - three shared
pairs of electrons.
• A double covalent bond is shown by a double line, and a triple bond by a
triple line.
• A molecule of oxygen (O2) consists of two oxygen atoms held together by a
double bond, like this:
• A molecule of nitrogen (N2) has two nitrogen atoms held together by a
triple bond, like this:
18. Dot – and – cross diagram
• Dot-and-cross diagrams are another
way to represent covalent bonds.
The shared electron from one atom
is shown as a dot, while the shared
electron from the other atom is
shown as a cross.
• When
drawing
dot-and-cross
diagrams for covalent bonds, you
only need to show the electrons in
the highest occupied energy level, as
only these are involved.
20. 1.
2.
3.
4.
5.
6.
7.
What is an Ion?
How did an ion became a cation?
How did an ion became an anion?
Mention 2 examples of Cation and Anion!
What is an ionic Compound?
What is a covalent bond?
Mention three ways to present covalent bonds!
