Transcript IONIC_BONDING

Ionic Bonding
Specification
• Candidates should be able to:
(a) describe the term ionic bonding as electrostatic attraction
between oppositely charged ions;
(b) construct ‘dot-and-cross’ diagrams, to describe ionic
bonding;
(c) predict ionic charge from the position of an element in the
Periodic Table;
(d) state the formulae for the following ions: NO3, CO32–, SO42–
and NH4+;
Lesson Objectives
1. Know the difference between an ion and an
atom
2. Describe the term ionic bond as electrostatic
attraction between oppositely charged
electrons
3. Draw cross and dot diagrams for given
compounds
4. Draw the bonding in given polyatomic ions
and state their overall charge
describe the term ionic bonding as electrostatic
attraction between oppositely charged ions;
• What is an ion?
– Ions are formed when one atom transfers
electrons from one atom to another
– Electrons can be gained or lost
– They generally do this in order to form a full outer
shell
An aluminium atom has the electron structure
2,8,3. It needs to lose 3 electrons to become
stable.
An oxygen atom has the electron structure 2,6. It
needs to gain 2 electrons in its outer shell to become
stable.
Lesson Objectives
• Lesson Objective 1- know the difference
between an atom and an ion
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Using the whiteboards + Periodic
tables predict what ions would be
formed by the following
Calcium
Nitrogen
Flourine
Potassium
Bromine
Oxygen
Ionisation equations
• Ca → Ca2+ + 2e• N + 3e- → 3N• Write down the equations for F,K,Br and O
Correct drawing of ion structures
Drawing Dot and Cross Diagrams
Sodium Chloride
Electrostatic Attraction
• This donation of electrons creates a positive
and a negative ion
• Because positives attract negatives a bond is
formed
• This bond is an electrostatic attraction or ionic
bond
Lesson Objectives
• Lesson Objective 2-Describe the term ionic
bond as electrostatic attraction between
oppositely charged electrons
An aluminium atom has the electron structure
2,8,3. It needs to lose 3 electrons to become
stable.
An oxygen atom has the electron structure 2,6. It
needs to gain 2 electrons in its outer shell to become
stable.
Aluminium
To work out the
number of ions of
each element we need
to balance the
number of electrons
being given and taken.
Oxygen
23+
2 x 3= 6 electrons
from the aluminium
and
23+
3 x 2 = 6 electrons to
the oxygen
2-
The formula is Al2O3
Questions
Draw dot and cross diagrams for the following
• LiF
• Na2O
• MgO
• AlCl3
• MgCl2
Polyatomic ions
• Poly-many
• Atomic-atoms
• E.g. hydroxide OH- (draw on board)
Lesson Objectives
Lesson Objective 3 Draw cross and dot diagrams
for given compounds
Extension Activity
• Draw cross and dot diagrams to show the
structures of the following NO3-, CO32–, SO42–
and NH4+
• Predict the charge on the following
polyatomic ions ClO (chlorate), PO4
(phosphate), MnO4 (permanganate) and S2O3
(thiosulphate)
• Lesson Objective 4 Draw the bonding in given
polyatomic ions and state their overall charge