Formation of compounds. What happens when a piece of burning sodium is placed in a gas jar of...
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Transcript of Formation of compounds. What happens when a piece of burning sodium is placed in a gas jar of...
Formation of compounds
What happens when a piece of burning sodium is placed in a gas jar of chlorine?
sodium chlorine
+
sodium chloride
Sodium gives 1 electron to chlorine
Cl
chlorine = 17 electrons : 2, 8, 7
sodium = 11 electrons : 2, 8, 1
Na
Before Bonding
Cl
chloride ion17 protons18 electrons
Charge - 1
Cl - = 2, 8, 8
sodium ion 11 protons10 electrons
Charge + 1
Na+ = 2 , 8
Na
This type of bonding is known as ionic bonding because the metal atoms transfer electron(s) to non-metal atoms and ions are formed.
Sodium atom loses an electron to form sodium ion Na +
Chlorine atom gains an electron to form chloride ion Cl-
Chemical formula of sodium chloride is NaClChemical formula of sodium chloride is NaCl
ClNa
After Bonding
When metal meet non-metals, the sparks will fly“Give me the electrons!” non-metal do cry
“you got a deal!” the metal respondsThe ions attract to form their bonds.
Lithium + fluorine Lithium + fluorine lithium fluoride lithium fluoride
Lithium gives 1 electron to fluorine
F
fluorine = 9 electrons : 2, 7
lithium = 3 electrons : 2, 1
Li
Before Bonding
F
fluoride ion9 protons10 electrons
Charge - 1
F - = 2, 8
lithium ion 3 protons2 electrons
Charge + 1
Li+ = 2
Li
Lithium atom loses an electron to form lithium ion Li +
Fluorine atom gains an electron to form fluoride ion F-
Chemical formula of lithium fluoride is LiFChemical formula of lithium fluoride is LiF
FLi
After Bonding
What happens when a piece of magnesium is burnt in air?
magnesium + oxygen magnesium oxide
Magnesium gives 2 electrons to oxygen
O
oxygen = 8 electrons : 2, 6
magnesium = 12 electrons : 2, 8, 2
Before Bonding
Mg
O
oxide ion8 protons10 electrons
Charge - 2
O 2- = 2, 8
magnesium ion 12 protons10 electrons
Charge + 2
Mg 2+ = 2 , 8
Mg
2+ 2-
Magnesium atoms lose 2 electrons to form magnesium ions Mg 2+
Oxygen atoms gain 2 electrons to form oxide ions O 2-
Chemical formula of magnesium oxide is MgOChemical formula of magnesium oxide is MgO
OMg
2+ 2-
After Bonding
Cl
ClMg
Mg = 12 electrons: 2, 8, 2
Cl = 17 electrons : 2, 8, 7
Cl
ClMg
2+
Mg 2+ = 2 , 8
Cl - = 2 , 8, 8
Magnesium lost 2 electrons to form magnesium ions Mg 2+
Each chlorine atom gained an electron to form chloride ions Cl –
Magnesium chloride is MgClMagnesium chloride is MgCl22
ClMg
2+
2
After Bonding
Sodium oxideSodium oxide
Na
Na
O
O : 8 electrons : 2, 6
Na: 11 electrons : 2, 8, 1
Na
Na
O
2-
Na + = 2 , 8O 2- = 2, 8
Na O
2-
2
Each sodium atom lost an electron to form sodium ions Na +
An oxygen atom gained 2 electrons to form an oxide ion O 2-
Sodium oxide is NaSodium oxide is Na2 2 OO
After Bonding
Potassium sulphidePotassium sulphide
S : 16 electrons : 2, 8, 6
K: 19 electrons : 2, 8, 8, 1
K
K
S
S 2- : 2, 8, 8K+ : 2, 8, 8
K
K
S
2-
Each potassium atom lost an electron to form potassium ions K +
A sulphur atom gained 2 electrons to form sulphide ion S 2-
Potassium sulphide is KPotassium sulphide is K2 2 SS
After Bonding
K S
2-
2
F
F = 9 electrons : 2, 7
Al
Al = 13 electrons: 2, 8, 3
F
F
F
F- : 2, 8
Al
Al 3+ : 2, 8
F
F
3+
After Bonding
Aluminium atom lost 3 electrons to form aluminium ions Al 3+
Each fluorine atom gained an electrons to form fluoride ion F –
Aluminium Fluoride is AlFAluminium Fluoride is AlF3 3
FAl
3+
3
Summary
Li
Na
K
Mg
Ca
Al
F
Cl
O
S
Metals transfer electrons to non-metal forming ions
Predict the formulas for the following ionic compounds:
Potassium bromide
Lithium oxide
Magnesium sulphide
Sodium iodide
Aluminium chloride
Calcium fluoride
KBr
Li2O
MgS
NaI
AlCl3
CaF2