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© Boardworks Ltd of 20 © Boardworks Ltd of 68 Atoms and electron changes Every atom would like to have a full outer shell like the noble gases. Atoms can get full outer electron shells by either gaining or losing electrons
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© Boardworks Ltd 20041 of 20 © Boardworks Ltd 20051 of 68
KS4 Chemistry
Ionic Bonding
© Boardworks Ltd 20041 of 20 © Boardworks Ltd 20052 of 68
Full electron shells
Atoms of noble gases, group 8, have completely full outer shells. This makes them very unreactive or stable.
1st shell holdsa maximum of
2 electrons
2nd shell holdsa maximum of
8 electrons
3rd shell holdsa maximum of
8 electrons
© Boardworks Ltd 20041 of 20 © Boardworks Ltd 20053 of 68
Atoms and electron changes
Every atom would like to have a full outer shell like the noble gases.
Atoms can get full outer electron shells by either gaining or losing electrons
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From atoms to ions
How can reactive metal atoms become stable positive ions?
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Bonding: example 1
• Making sodium chloride – table salt!!!
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It will have to gain an electron!!!
What would a chlorine atom have to do to have a stable electron configuration like a noble gas?
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What would a sodium atom have to do to have a stable electron configuration like a noble gas?
It will have to lose an electron!!!
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Can you think of a way that chlorine could gain an electron and sodium could lose an electron?
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Sodium gives an electron to chlorine!!!
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Once this happens both of the atoms will now be ions and will each have a charge!!
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The oppositely charged ions attract each other and form an ionic bond!!
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© Boardworks Ltd 20041 of 20 © Boardworks Ltd 200513 of 68
Key definitions
An ionic bond is formed when ions that have opposite charges attract
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Formation of an ionic bond
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+ - + - + -+- + - +-
+ + ++ + +
+ + +
- - -- - -
- - -
- + - + -++ - +-
+ ++ + +
+ +
- - -
+-
+
+
-- -- - -
Ionic lattices
In an ionic compound, millions and millions of ions are packed all joined by ionic bonds
+ - + - + -
+- + - +-
+ + ++ + +
+ + +
- - -- - -
- - -
- + - + -
++ - +-
+ ++ + +
+ +
- - -
+-
+
+
-- -- - -
+ - + - + -
+- + - +-
+ + ++ + +
+ + +
- - -- - -
- - -
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Bonding example 2
• Making Magnesium oxide
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What would magnesium need to do to get a stable full outer shell?
Mg
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O
What would oxygen need to do to get a stable full outer shell?
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Mg O
Can you think of a way that Magnesium could lose two electrons and oxygen could gain two electrons?Magnesium gives two electrons to oxygen!
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Once this happens the Magnesium and Oxygen atoms each get charge and become ions of opposite charge
2.8.2 2.6[2.8]2+ [2.8]2-
Mg
2+2-
O
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Magnesium oxide: part 2
Mg O
The positive magnesium ions and the negative oxygen ions are strongly attracted to each other and form an ionic bond.
+2 -2
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+ - + - + -+- + - +-
+ + ++ + +
+ + +
- - -- - -
- - -
- + - + -++ - +-
+ ++ + +
+ +
- - -
+-
+
+
-- -- - -
Ionic lattices
In an ionic compound, millions and millions of ions are packed together in a regular cubic arrangement, joined by ionic bonds..
+ - + - + -
+- + - +-
+ + ++ + +
+ + +
- - -- - -
- - -
- + - + -
++ - +-
+ ++ + +
+ +
- - -
+-
+
+
-- -- - -
+ - + - + -
+- + - +-
+ + ++ + +
+ + +
- - -- - -
- - -
© Boardworks Ltd 20041 of 20 © Boardworks Ltd 200523 of 68
Formation of an ionic bond
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Multiple-choice quiz
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Compounds
Compounds are made up of two OR MORE different elements chemically combined
Example: water – H20
O
H
H
Others compounds, like DNA, have large, complex structures containing thousands or even millions of bonded atoms.