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IONIC BONDING
HOW DOES IT WORK?Ionic bonding takes place between metals and non-
metals
Metal atoms try to attain noble gas strucure (full outer shells) by losing electrons to form positive ions
Non-metal atoms try to attain noble gas strucure (full outer shells) by gaining electrons to form negative ions
The positive and negative ions formed attract each other to give an ionic bond.
Sodium Chloride
Sodium has atomic number 11
It therefore has 11 protons in its nucleus
+ + + + + +++ + + +
It also has 11 electrons2 in the inner shell8 in the next shell
1 in the outer shell
SODIUM
Sodium has 11 protons = 11 + charges
Sodium has 11 electrons = 11 - charges
Total = 0. It is a neutral atom
Chlorine has atomic number 17
The number of protons in its nucleus is
+ + + + + +++ + + +
The number of electrons is In the inner shellIn the next shell
In the outer shell
17
1728
7
++ + ++ +
Chlorine has 17 protons = 17 + chargesIt also has 17 electrons = 17 - charges
TOTAL = 0. It is a neutral atom
CHLORINE
Sodium Atom Chorine Atom
Sodium loses one electron to gain noble gas structure (complete outer shell)
Chlorine gains the electron and also gets a complete outer shell of 8 electrons
Now the sodium has11protons (still) = 11+ chargesBut only 10 electrons = 10- charges
Total = +1 which is the charge on the SODIUM ION
+
The chlorine has17protons (still) = 17+ charges
But only 18 electrons = 18- charges
Total = -1 which is the charge on the CHLORIDE ION
-
Both Atoms want complete outer shells of electrons
Sodium Ion Chloride Ion
Magnesium Oxide
MAGNESIUM
Magnesium has atomic Number 12
It therefore has 12 protons in the nucleus
And 12 electrons arranged 2.8.2
12p
OXYGEN
Oxygen has atomic Number 8
It therefore has 8 protons in the nucleus
And 8 electrons arranged 2.6
8p
Magnesium needs to lose 2 electrons to get a complete outer shell
Oxygen needs to gain 2 electrons to get a complete outer shell
Magnesium still has 12 protons = 12+But only 10 electrons = 10 –So overall charge = 2+The ion is written Mg2+
2+
Oxygen still has 8 protons = 8+But now 10 electrons = 10 –So overall charge = 2-The ion is written O2-
2-
Magnesium Fluoride
MAGNESIUM
Magnesium has atomic Number 12
It therefore has 12 protons in the nucleus
And 12 electrons arranged 2.8.2
12p
FLUORINE
Fluorine has atomic Number 9
It therefore has 9 protons in the nucleus
And 8 electrons arranged 2.7
Magnesium needs to lose 2 electrons to get a complete outer shell
But Fluorine needs to gain only 1 electrons to get a complete outer shell
8p
Therefore another fluorine is needed
8p
This gives us the Mg2+ ionAnd two F- ions
The formula is MgF2
IONIC STRUCTURES
POSITIVE ION NEGATIVE ION
Now opposite charges attract!
Positive ions and negative ions form a lattice .
Every positive ion is surrounded by negative ions and every negative ion is surrounded by positive ions.
PROPERTIES OF IONIC COMPOUNDS
Salt Crystals (sodium chloride)
Copper Sulphate crystals
They are crystalline solids
They have high melting points
Many dissolve in water
If melted or dissolved in water, they conduct electricity.