Bonding
What do you know about
bonding?
Learning Objectives
• Define Key terms.
• Describe Ionic Bonding
• Construct Dot/Cross diagrams for ionic
compounds.
Match up
Ionic Bonding
Formed when atoms of
different elements chemically
bond together
Covalent Bonding
Generally a metal bonded to
a non metal. Electrons are
transferred, and ions are
formed.
Metallic bonding.
Electrons are shared
between all the atoms
(delocalised outer electrons)
Compound
Electrons are shared
between 2 non metals
Now look in your book for a copy of the
‘definition’ what do you think the key parts
are??
Ionic Bonds
• Electrons are
transferred from the
metal atom to the non
metal atom.
• Oppositely charged
ions are formed which
are held together by
electrostatic
attraction.
• A giant ionic lattice is
formed.
THE IONIC BOND
Ionic bonds tend to be formed between elements whose atoms need to “lose”
electrons to gain the nearest noble gas electronic configuration (n.g.e.c.) and
those which need to gain electrons. The electrons are transferred from one
atom to the other.
_
Sodium Chloride
Na 1s2 2s2 2p6 3s1
Cl 1s2 2s2 2p6 3s2 3p5
Na+ 1s2 2s2 2p6
Cl¯1s2 2s2 2p6 3s2 3p6
An electron is transferred from the 3s orbital of sodium to the 3p
orbital of chlorine; both species end up with the electronic configuration of the
nearest noble gas the resulting ions are held together in a crystal lattice by
electrostatic attraction.
Half equations and electron configurations
Na
——> Na+ + e¯
1s2 2s2 2p6 3s1
1s2 2s2 2p6
Cl + e¯ ——> Cl¯
1s2 2s2 2p6 3s2 3p5
1s2 2s2 2p6 3s2 3p6
THE IONIC BOND
FORMATION OF MAGNESIUM CHLORIDE
e¯
Cl
ELECTRON
Mg
TRANSFER
Cl
e¯
Mg
——>
Mg2+ + 2e¯
and
2Cl + 2e¯
——> 2 Cl¯
What would the electron configurations be? For all species? (4 of them)
Draw your own diagrams with electron configurations and half equations for:
Calcium oxide (CaO), Sodium Oxide (Na2O) and Aluminium Fluoride (AlF3)
This question is about different models of
bonding and molecular shapes.
Magnesium sulfide shows ionic
bonding.
(i)
What is meant by the term ionic
bonding?
.....................................................................
....................................................
.....................................................................
....................................................
[1]
(ii)
Draw a ‘dot-and-cross’ diagram to
show the bonding in magnesium sulfide.
Show outer electron shells only.
Ionic bonding and the periodic table
• 1. Drawn a dot/cross diagram (outer shell)
for a) MgO, b) CaBr2, c) Na3P, d) Al2O3
• 2. Write out the electron configuration for
K and K+, S and S2-
Learning Objectives
• State common molecular ions
• Be able to predict ionic charge
• Apply to exam questions
Notes
• In general:
• Group 1-3 lose elctrons to form the configuartion of PREVIOUS
noble gas.
• Group 5-7 gain electrons to form the configuration of the NEXT
noble gas.
• Be, C, B and Si don’t tend to form ions due to too much energy
being required to remove electrons.
• Transistion Metals:
• Iron (II) Fe 2+
• Copper (I) Cu+
Iron (III) Fe 3+
Copper (II) Cu 2+
(Just look at the roman numerals)
Ions formed
1
Atom Li
2
3
4
5
6
7
Be
B
C
N
O
F
Mg
Al
Si
P
S
Cl
Ion
Atom Na
Ion
Atom K
Ion
Ca
Br
Molecular Ions
1+
1-
2-
3-
Ammonium
NH4+
Hydroxide OH-
Carbonate
CO32-
Phosphate
PO43-
Nitrate NO3-
SulphateSO42-
Nitrite NO2-
Sulphite SO32-
Hydrogen
Carbonate
HCO3-
Dichromate
Cr2O72-
• Some such as NH4+ and OH- can be worked out.
• Others such as sulphate, think about what the acid would be.
•
Working out ionic formulae
Calcium Atom
Chloride
Ion
Charge
Ratio
Ca
Ca2+
2+
1
Cl
Cl-
-
2
= CaCl2
Questions
Lithium
Nitride
Calcium
Iodide
Aluminium
Sulphide
Magnesium
Phosphide
Nickel (II)
Chloride
Copper(I)
Oxide
Iron (III)
Chloride
Titanium (IV)
Chloride
Aluminium
Sulpahte
Calcium
Hydroxide
Iron (III)
Sulphite
Chronium (III)
Nitrite
Manganese
(VI) Oxide
Chromium
(III) Oxide
Ammonium
Phosphate
Sodium
Dichromate
Apply to exam question