ks4 chemistry
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KS4 Chemistry. Ionic Bonding. Full electron shells. 2 nd shell holds a maximum of 8 electrons. 1 st shell holds a maximum of 2 electrons. 3 rd shell holds a maximum of 8 electrons. - PowerPoint PPT PresentationTRANSCRIPT
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KS4 Chemistry
Ionic Bonding
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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
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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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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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+
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++
-
+
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+ ++ + +
+ +
- - -
+-
+
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-- -- - -
+
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+
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+
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+
-
+
-
+
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+ + ++ + +
+ + +
- - -- - -
- - -
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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..
+-
+-
+-
+
-
+
-
+
-
+ + ++ + +
+ + +
- - -- - -
- - -
-
+
-
+
-
++
-
+
-
+ ++ + +
+ +
- - -
+-
+
+
-- -- - -
+
-
+
-
+
-
+
-
+
-
+
-
+ + ++ + +
+ + +
- - -- - -
- - -
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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.