Bonding

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Bonding

• Chemistry revision

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There are two types of bonding you need to be
familiar with

1. Covalent bonding
2. Ionic bonding

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You will be re-visiting
The structure of the atom. Why atoms want to lose
or gain electrons. Which type of materials use
covalent or ionic bonding. The properties that
covalent and ionic bonding give to the material.
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You need to be able to
Name the components of an atom. Understand how
many electrons are in each orbital. Describe the
charge on each sub atomic particle. Understand
what an isotope is. To draw dot and cross
diagrams. To draw ionic formula diagrams. To name
compounds which use these types of bonding
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The atom
Atoms contain three sub-atomic particles called
protons, neutrons and electrons. The protons
and neutrons are found in the nucleus at the
centre of the atom, and the electrons are
arranged in shells around the nucleus.
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The charge in an atom

• Atomic heaven is to be neutral!
• Atoms will share or steal electrons so they can
  to obtain the structure of the Group 0 or Noble
  elements.
• This group reacts with very little at all!
• By sharing or stealing electrons the atoms bond
  to become compounds and therefore neutral!

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There are two properties of sub-atomic particles
that are especially importantMassElectrical
charge
Particle Charge Relative Mass
Protons 1 1
Neutrons 0 1
Electrons -1 0.0005
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So now we look at the Periodic Table
Here is the element Carbon
Atomic Number the number of protons in the
nucleus.It is the smaller number in the box.
Atomic Mass the number of protons and neutrons
in the nucleus.It is the larger number in the box.
12 C 6
From these two numbers we can work out the number
of electrons this element should have.
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Carbon can also be an isotope
Isotopes have the same number of protons but a
different number of neutrons. So isotopes have
the same atomic number but a different atomic
mass.
126 C or 146 C Other famous isotopes are
uranium and radium
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Where are the electrons?
The electrons are located in orbitals or shells
around the nucleus. The innermost orbital will
take up to two electrons only. The next three
orbitals will take a maximum of eight electrons
each.
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Covalent Bonding

• Covalent compounds are formed when non-metal
  atoms react together.
• As these atoms come near their outer electrons
  are attracted to the nucleus of both atoms and
  become shared by the atoms.
• The shared electrons count towards the shells of
  both atoms and therefore help fill up incomplete
  electron shells.

Boardworks Covalent Bonding
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Examples of covalent bonding
Simple covalent bonds Water H2O Ammonia
NH3 Methane CH4 Oxygen O2 Giant covalent
structures Graphite Diamond
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Properties of covalent compounds
Small numbers of atoms in the molecules. Low
melting and boiling points. Most are gases or
liquids at room temperature. They do not conduct
electricity. They tend to be insoluble in water.
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Ionic bonding
Most ionic compounds contain a metal and a
non-metal.
When metals react they lose outer shell electrons
to leave a full electron shell.
This produces a charged atom (ion) with a
charge.
When non-metals react with a metal they gain
electrons to achieve a full electron shell.
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Examples of ionic structures
http//www.chem.ox.ac.uk/icl/heyes/structure_of_so
lids/Movies/NaCl.html
Animation of NaCL
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Properties of ionic compounds
Atoms are held very strongly together. The
compound has a regular structure. Ions form giant
structures. Very high melting and boiling
points. Soluble in water. Conducts electricity
when dissolved.
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OK, have a go at this quiz and check what you
should know
http//www.sciencepages.co.uk/keystage4/GCSEChemis
try/module3.php
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This is the structure of Argon
Its electronic configuration is written 2,8,8
Which group of the Periodic Table will it be
found in?