Chemistry 5072 Dot-and-cross diagram Ionic bonding Hence the ionic bond is an electrostatic force.
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Transcript of Chemistry 5072 Dot-and-cross diagram Ionic bonding Hence the ionic bond is an electrostatic force.
Chemistry 5072Chemistry 5072
Dot-and-cross diagramDot-and-cross diagram
Ionic bondingIonic bondingHence the ionic bond is an electrostatic forceHence the ionic bond is an electrostatic force
Ionic bondingIonic bonding Ionic bonds are formed between atoms of metals
and atoms of non-metals, as a result of the transfer of electrons.
Compounds formed by ionic bonding are called ionic compounds. Metals react with non-metals to form ionic compounds.
Note : The particles present in ionic compounds are ions; there are NO molecules in ionic compounds.
Ionic bonds are formed between atoms of metals and atoms of non-metals, as a result of the transfer of electrons.
Compounds formed by ionic bonding are called ionic compounds. Metals react with non-metals to form ionic compounds.
Note : The particles present in ionic compounds are ions; there are NO molecules in ionic compounds.
More Practice1. Draw ‘dot and cross’ digrams to show the formation of :
Calcium oxide
Magnesium chloride
Sodium oxide
2. Draw ‘dot and cross’ diagram to show the bonding in
O atom 2,6
Ca2+ ion O2- ion Ionic bond(electrostatic force)
x xx
xx
x x
xx
xx
x
x
xxx
xx
xx
Ca atom 2,8,8,2
Calciumoxide(CaO)
2+
x
2-x
xxxx
xx
xx
xxxx
xx
xx
xx
2,8,8 2,8
transfer of 1 electron
transfer of 1 electron
O atom 2,6
Ca2+ ion O2- ion Ionic bond(electrostatic force)
x
x
Ca atom2,8,8,2
Calciumoxide(CaO)
2+
x
2-x
xx
xx
xx
xx
2,8,82,8
transfer of 1 electron
transfer of 1 electron
O
O
Ca
Ca
Note: onlyvalence shellsare shown
2,8,2
x xx
xx
x
x
xx
x2,8,7
x x
x
2 Cl¯ ions
¯
Mg2+ ion
x x xx
x
xx
x
xx
2+
MagnesiumchlorideMgCl2
transfer of 1 electron
transfer of 1 electron
2,8 2,8,8
2
Mg atom
Cl atoms
2,8,2
x
x2,8,7
x
2 Cl¯ ions
¯
Mg2+ ion
xx
x
xx
x
xx
2+
MagnesiumchlorideMgCl2
transfer of 1 electron
transfer of 1 electron
2,8 2,8,8
2
Mg atom
Cl atoms
Note: onlyvalence shellsare shown
Mg
Mg
Cl
Cl
Cl
Chemical formulae of ionic compoundsChemical formulae of ionic compounds
An easy method of writing a chemical formula involving 2 ions is to ‘criss-cross’ the charges
An easy method of writing a chemical formula involving 2 ions is to ‘criss-cross’ the charges
Eg. Write the formula of aluminium oxide.
Ions: Al3+ O2-
Eg. Write the formula of aluminium oxide.
Ions: Al3+ O2-
Chemical formula: Al2O3
Check that the total positive charge and total negative charge are equal
Chemical formula: Al2O3
Check that the total positive charge and total negative charge are equal
Chemical formulae of ionic compoundsChemical formulae of ionic compounds
Write the formula of magnesium carbonate.
Ions: Mg2+ CO3 2-
Chemical formula: MgCO3
Check that the total charges are balanced.
Write the formula of magnesium carbonate.
Ions: Mg2+ CO3 2-
Chemical formula: MgCO3
Check that the total charges are balanced.
All subscripts are in the simplest set of whole
numbers
Chemical formulae of ionic compoundsChemical formulae of ionic compoundsWrite the formula of calcium nitrate.
Ions: Ca2+ NO3 -
Write the formula of calcium nitrate.
Ions: Ca2+ NO3 -
a) subscript ‘1’ is not written
b) Polyatomic ions should be written within brackets if there is a subscript attached
Chemical formula: Ca(NO3)2
Check that the total charges are balanced.
Properties of ionic compoundsProperties of ionic compounds
High melting and boiling points Usually soluble in water Low volatility Conducts electricity only in molten or
aqueous state
Physical properties: