It's very good for SPM students . You have to learn the ionic bond thoroughly. If you understand well you can explain it vividly. For other chemistry notes can email me puterizamrud@gmail.com or facebook Pusat Tuisyen Zamrud .

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SPM Form 4 Chemistry - Chemical Bonds
http://spmchemistry.onlinetuition.com.my/2013/10/chemical
-bond.html
1. Stability of Noble Gases
2. Chemical Bond
3. Formation of Ion
a. Formation of Positive Ion
b. Formation of Negative Ion
c. Difference Between an Atom and an Ion That Have Same Electrons
Arrangement
4. Ionic Bonding
5. Predicting the Formula of Ionic Compounds (Video)
6. Covalent Bonding
o Number of Bond
o Predicting the Formula of Covalent Compounds
7. Physical Properties of Ionic and Covalent Compound
. Ionic Compound
a. Covalent Compounds
i. Simple Molecule
ii. Macromolecular compounds
8. Mind Map
Stability of Noble Gases
1. Group 18 elements (Noble Gases) exist as monoatom in nature.
2. They are inert in nature and do not react with any other elements (or
themselves) to form any chemical compounds.
3. In other words, they are chemically very stable (or chemically very non-
reactive).
Duplet and Octet Electron Arrangement

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1. The charge on the nucleus and the number of electrons in the valence shell
determine the chemical properties of an atom.
2. The stability of noble gas is due to their electrons arrangement.
3. The diagram above shows the first four elements of Noble Gas. We can see
that the outer most shell (valence shell) of Helium has 2 electrons. We call this
duplet electron arrangement.
4. The maximum number of electrons can be filled in the first shell is 2 electrons,
which means 2 electrons in the first shell is considered FULL.
5. The valence shell all other Group 18 elements (including Xenon and Radon
which is not shown in the diagram) has 8 electrons, and we call this octet electron
arrangement.
6. When the electron arrangement of an atom is duplet or octet, the energy of the
electrons is very low, and it is very difficult (even though it is not impossible) to add
or remove electrons from the atom.
7. This explains why noble gases are reluctant to react with all other elements.
The Octet Rule
1. Atoms of other main group elements which are not octet tend to react with
other atoms in various ways to achieve the octet.
2. The tendency of an atom to achieve an octet arrangement of electrons in the
outermost shell is called the octet rule.
3. If the outermost shell is the first shell, then the maximum number of electrons
is two, and the most stable electron arrangement will be duplet.

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4. A configuration of two electrons in the first shell, with no other shells
occupied by electrons, is as stable as the octet electron arrangement and therefore is
also said to obey the octet rule.
How Atoms Achieve Duplet or Octet Electron Arrangement?
1. Atoms can achieve duplet or octet electron arrangement in 3 ways:
a. throw away the excess electron(s)
b. receiving electron(s) from other atom if they are lack of electron(s)
c. sharing electron
(A sodium atom throws away an electron to achieve octet electron arrangement)
(A fluorine atom receives one electron to achieve octet electron arrangement)

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(Two fluorine atoms share one pair of electrons to achieve octet electron arrangement)
Chemical Bond
1. 2 types of chemical bonds are commonly formed between atoms, namely
a. Ionic Bond
b. Covalent Bond
The Ionic Bond
(Ionic Bond)
1. By releasing or receiving electron(s), the atoms will become ions and
consequently form ionic bond between the ions.
2. Ionic bonds are always formed between metal and non-metal. For example,
sodium (metal) react with chlorine (non-metal) will form an ionic bond between
sodium ion and chloride ion.
3. The compounds formed are called the ionic compounds.
4. Some time, an ionic bond is also called electrovalent bond.

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The Covalent Bond
(Covalent Bond)
1. By sharing electron(s), the atoms will form covalent bond between the atom
and the molecule formed is called the covalent molecule.
2. Covalent bond is always formed between non-metal with another non-metal.
Formation of Positive Ion
1. Usually, the atom of metals consist of 1, 2 or 3 valence electrons.
2. In order to achieve octet electrons arrangement, the atoms will release the
valence electrons.
3. After releasing the valence electrons, the protons in the nucleus will out
number the electrons. As a result, positive ions formed.
Example: Formation of Ion with +1 ChargeThere are two types of atomic
bonds - ionic bonds and covalent bonds. They differ in their structure
and properties. Covalent bonds consist of pairs of electrons shared by two
atoms, and bind the atoms in a fixed orientation. Relatively high energies are
required to break them (50 - 200 kcal/mol). Whether two atoms can form a
covalent bond depends upon their electronegativity i.e. the power of an atom
in a molecule to attract electrons to itself. If two atoms differ considerably in
their electronegativity - as sodium and chloride do - then one of the atoms
will lose its electron to the other atom. This results in a positively charged ion
(cation) and negatively charged ion (anion). The bond between these two ions
is called an ionic bond.

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Comparison chart</> Em bed this chart
Covalent Bonds Ionic Bonds
Polarity Low High
Formation
A covalent bond is formed between two non-
metals that have similar electronegativities.
Neither atom is "strong" enough to attract
electrons from the other. For stabilization,
they share their electrons from outer
molecular orbit with others.
An ionic bond is formed betweena metal
and a non-metal. Non-metals(-ve ion) are
"stronger" than the metal(+ve ion) and
can get electrons very easilyfrom the
metal. These two opposite ions attract
each other and form the ionic bond.
Shape Definite shape No definite shape
What is it?
Covalent bonding is a form of chemical
bonding betweentwo non metallic atoms
which is characterized by the sharing of pairs
of electrons betweenatoms and other
covalent bonds.
Ionic bond, also known as electrovalent
bond is a type of bond formed from the
electrostatic attraction between
oppositely charged ions in a chemical
compound. These kinds of bonds occur
mainly between a metallicand a non
metallic atom.
Melting point low High
Examples
Methane (CH4), Hydro Chloric acid (HCl) Sodium chloride (NaCl),Sulphuric Acid
(H2SO4 )
Occurs
between
Two non-metals One metal and one non-metal
Boiling point Low High
State at room
temperature
Liquid or gaseous Solid
Contents
 1 About Covalent and Ionic Bonds

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 2 Formation and examples
o 2.1 Examples (video)
 3 Characteristics of thebonds
 4 Video comparing types of atomic bonds
 5 Further Reading
 6 References
About Covalent and Ionic Bonds
The covalent bond is formed when two atoms are able to share electrons whereas
the ionic bond is formed when the "sharing" is so unequal that an electron from
atom A is completely lost to atom B, resulting in a pair of ions.
Each atom consists of protons, neutrons and electrons. At the centre of the atom,
neutrons and protons stay together. But electrons revolve in orbit around the
centre. Each of these molecular orbits can have a certain number of electrons to
form a stable atom. But apart from Inert gas, this configuration is not present with
most of the atoms. So to stabilize the atom, each atom shares half of its electrons.
Covalent bonding is a form of chemical bonding between two non metallic atoms
which is characterized by the sharing of pairs of electrons between atoms and other
covalent bonds. Ionic bond, also known as electrovalent bond is a type of bond
formed from the electrostatic attraction between oppositely charged ions in
a chemical compound. This kind of bonds occurs mainly between a metallic and a
non metallic atom.
Formation and examples
Covalent bonds are formed as a result of the sharing of one or more pairs of bonding
electrons. The electronegativities (electron attracting ability) of the two bonded
atoms are either equal or the difference is no greater than 1.7. As long as the electro-
negativity difference is no greater than 1.7, the atoms can only share the bonding
electrons.

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A model of the double and single covalent bonds ofcarbonwithin a benzene ring.
For example, let us consider a Methane molecule i.e.CH4.Carbon has 6 electrons and
its electronic configuration is 1s22s22p2, i.e. it has 4 electrons in its outer orbit.
According to the Octate rule ( It states that atoms tend to gain, lose, or share
electrons so that each atom has full outermost energylevel which is typically 8
electrons.), to be in a stable state, it needs 4 more electrons. So it forms covalent
bond with Hydrogen (1s1), and by sharing electrons with hydrogen it
forms Methane or CH4.
If the electro-negativity difference is greater than 1.7 then the
higher electronegative atom has an electron attracting ability which is large enough
to force the transfer of electrons from the lesser electronegative atom. This causes
the formation of ionic bonds.
Sodium and chlorine bonding ionically to form sodium chloride.
For example, in common table salt (NaCl) the individual atoms are sodium and
chlorine. Chlorine has seven valence electrons in its outer orbit but to be in a stable
condition, it needs eight electrons in outer orbit. On the other hand, Sodium has
one valence electron and it also needs eight electrons. Since chlorine has a high
electro-negativity, 3.16 compared to sodium’s 0.9, (so the difference between their
electro-negativity is more than 1.7) chlorine can easily attract sodium's one valence
electron. In this manner they form an Ionic bond, and share each other’s electrons
and both will have 8 electrons in their outer shell.

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(A sodium atom release one electron to form a sodium ion with +1 charge)
Example: Formation of Ion with +2 Charge
(A sodium atom release one electron to form a sodium ion with +2 charge)
Example: Formation of Ion with +3 Charge
(A sodium atom release one electron to form a sodium ion with +3 charge)

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Difference Between an Atom and an Ion That Have Same
Electrons Arrangement
Difference Between Fluoride Ion and Neon Atom
1. After forming an ion, the electron arrangement of the ion is similar to the
noble gases.
2. For example, the electron arrangement of fluoride ion is 2.8 which is similar to
a Neon atom, 2.8.
3. Fluoride ion and the neon atom have similar electron arrangement.
4. Fluoride ion carries charge whereas neon atom is neutral.
(The electrons arrangement of a fluoride ion is the same as a neon atom. However, they are so much
different chemically)
Ionic Bonding
Ionic Bonding
1. Ionic bonds are formed by one atom transferring electrons to another atom
to formions.
2. Ions are atoms, or groups of atoms, which have lost or gained electrons.
3. The atom losing electrons forms a positive ion (a cation) and is usually a
metal.
4. The atom gaining electrons forms a negative ion (an anion) and is usually a
non-metallic element.
5. Ions of opposite charge will attract one another by strong electrostatic force,

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thus creating an ionic bond.
6. Ionic bond is also known as electrovalence bond.
Example: Ionic Bonding between Group 1 Metals and Group 17 Elements
1. Figure above shows the illustration of the formationof ionic bond between a
sodium atom (group 1 metal) and a chlorine atom (group 17 element).
2. The electron arrangement of sodium atom is 2.8.1, which is not octet and
hence not stable.
3. To achieve octet electrons arrangement, the sodium atom donate/release
one electron and formsodium ion.
4. The electron arrangement of chlorine atomis 2.8.7, which is also not octet
and hence not stable, too.
5. To achieve octet electrons arrangement, the chlorine atomreceives one
electron from sodium atomand form a chloride ion.
6. The sodium ion and the chloride ion carry opposite charge, hence they attract
each other and forman ionic bond between each other.
Example: Ionic Bonding between Group 2 Metals and Group 17 Elements

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1. Figure above shows the illustration of the formationof ionic bond between
two potassium atoms (group 1 metal) and an oxygen atom(group 16 element).
2. The electron arrangement of potassium atomis 2.8.8.1,which is not octet
and hence not stable.
3. To achieve octet electrons arrangement, the potassium atom donate/release
one electron and formpotassium ion.
4. The electron arrangement of oxygen atom is 2.6, which is also not octet and
hence not stable, too.
5. To achieve octet electrons arrangement, the oxygen atomreceives two
electrons from potassium atoms and form an oxide ion.
6. The potassium ions and the oxide ion carry opposite charge, hence they
attract each other and form two ionic bond between the ions.
Example: Ionic Bonding between Group 2 Metals and Group 16 Elements

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1. Figure above shows the illustration of the formationof ionic bond between a
calcium atom (group 2 metal) and an oxygen atom (group 16 element).
2. The electron arrangement of calcium atom is 2.8.8.2, which is not octet and
hence not stable.
3. To achieve octet electrons arrangement, the potassium atom donate/release
two electrons and form calcium ion.
4. The electron arrangement of oxygen atom is 2.6, which is also not octet and
hence not stable, too.
5. To achieve octet electrons arrangement, the oxygen atomreceives two
electrons from the calcium atom and forman oxide ion.
6. The calcium ion and the oxide ion carry opposite charge, hence they attract
each other and forman ionic bond between each other.
Chemistry Form 4: Chapter 5 - Ionic Bond
 Ionic bonds are formed when valence electrons are transferred from a metal atom to
a non-metal atom.
 Metal atom releases valence electron to form positive ion in order to achieve stable
noble gas octet electron arrangement.
 Non-metal atom gains valence electron to form negative ion in order to achieve
stable noble gas octet electron arrangement.

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 Positive ions and negative ions are held strongly by electrostatic force.
Chemistry Form 4: Chapter 5 - Covalent Bond
Covalent bonds are formed when one or more electron pairs are shared between non-metallic
atoms to form a molecule in order to achieve a stable duplet or octet electron arrangements of
noble gas.
How covalent bond is formed in carbon dioxide:
 Atom oxygen has 6 valence electrons and 2.6 electron arrangement.

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 Each atom oxygen needs 2 more electrons to fill the valence shell in
order to achieve a stable octetelectron arrangement. Hence, each atom
oxygen contributes 2 electrons forsharing.
 Atom carbon has 4 valence electrons and 2.4 electron arrangement.
 Each atom carbon needs 4 more electrons to fill the valence shell in
order to achieve a stable octetelectron arrangement. Hence, each atom
carbon contributes 4 electrons for sharing.
 One atom carbon shares 4 electrons with two atom oxygen to
achieve a stable octet electronarrangement.
Some examples of covalent bond:

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Types of covalent bond:
Covalent Bonding
Covalent Bonding
1. Covalent bonds are formed by atoms sharing electrons to form molecules.
This type of bond usually formed between two non-metallic elements.
2. In the formationof covalent bonds, atoms of non-metals will combine with
each other to donate one, two or three electrons for sharing.
3. The compound formed through the formationof covalent bonds is called the
covalent compounds.
Examples of Covalent Compound
Covalent
Compound
Formula Covalent
Compound
Formula
Chlorine Cl2 Phosphorus P4
Hydrogen H2 Sulfurdioxide SO2
Oxygen O2 Carbondioxide CO2
Nitrogen
N2 Tetrachloro-
methane
CCl4

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Examples of Formation of Covalent Compounds
Formation of Fluorine Molecule
1. The electrons arrangement of a fluorine atom is 2.7
2. To achieve octet electrons arrangement, 2 fluorine atoms share 1 pair of electrons
between each other.
3. As a result, a covalent bond formed between the 2 atoms.
Number of Bond
Number of Bond
1. There are 3 types of covalent bond:
a. Single covalent bond – sharing of one pair of electrons
b. Double covalent bond – sharing of two pairs of electrons
c. Triple covalent bond – sharing of three pairs of electrons
Example
Number of electron Example and type of covalent bond
1 pair type of covalent bond: Single Bond
2 pair type of covalentbond:Double Bond

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3 pair type of covalentbond:Triple Bond
FormationofSingle Bond (HydrogenMolecule)
FormationofDouble Bond (OxygenMolecule)

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FormationofTripleBond (Nitrogen Molecule)

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Predicting the Molecular Formula of Covalent Compounds
1. Like the formula of ionic compounds, the formula of most covalent compounds can be
predicted by referring to the group in periodic table of the elements in the compound.
2. We can predict the formula of a covalent compound by referring to the valency of the
elements in the compound, if we know which group in periodic table the element is located.
3. The valency of an atom is the number of electrons receive of release to achieve octet
electrons arrangement.
4. For example, the electron arrangement of an oxygen atom is 2.6. To achieve octet electrons
arrangement, the oxygen atom need to receive 2 electrons. Therefore, the valency of oxygen is
2.
5. Table below shows the group of the elements, the valency of the elements and the predicted
formula of covalent compounds formed among the elements.
Element that combine Formula of the ionic compound
Element X from Valency Element Y from Valency
Group 15 3 Group 15 3 XY
Group 15 3 Group 16 2 X2Y3
Group 15 3 Group 17 1 XY3
Group 16 2 Group 16 2 XY
Group 16 2 Group 17 1 XY2
Group 17 1 Group 17 1 XY

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Formation of Oxygen Molecule
1. The electrons arrangement of an oxygen atomis 2.6
2. To achieve octet electrons arrangement, 2 fluorine atoms share 2 pair of
electrons between each other.
3. As a result, 2 covalent bonds formed between the 2 atoms.
Formation of Carbon Dioxide Molecule
1. The electrons arrangement of an oxygen atomis 2.6 and the electrons
arrangement of a hydrogen atom is 1.
2. To achieve octet electrons arrangement, the oxygen atomshare 2 pair of
electrons with 2 hydrogen atoms.

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3. The hydrogen atoms achieve duplet electrons arrangement aftersharing
electron with the oxygen atom.
4. As a result, covalent bonds formed between the oxygen atom and the
hydrogen atoms.
Physical Properties - Ionic Compounds
Structure Ionic Compound
1. In an ionic compound, the alternate positive and negative ions in an ionic solid
are arranged in an orderly way as shown in the image to the right.
2. The ions can form a giant ionic lattice structure with ionic bond between the
ions.
3. The ionic bond is the strong electrical attraction (electrostatic force) between
the positive and negative ions next to each other in the lattice.

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(Giant Lattice Structure)
(Strong Electrostatic Force formed between the positive and negative ions)
Properties of Ionic Compounds
1. The strong bonding force makes ionic compounds has high melting and
boiling points.
2. All ionic compounds are crystalline solids at room temperature.
3. They are hard but brittle, when stressed the bonds are broken along planes of
ions which shear away.
4. Many, ionic compounds (but not all) are soluble in water.
5. The solid crystals DO NOT conduct electricity because the ions are not free to
move to carry an electric current.
6. However, if the ionic compound is melted or dissolved in water, the liquid will
now conduct electricity, as the ion particles are now free.
Physical Properties of Covalent Compounds - Simple
Molecule
Covalent compounds can be divided into 2 types:
1. Simple molecular compound
2. Macromolecular compound
Simple Molecules

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1. Most covalent compounds are made up of independent molecular units, as
shown in figure above.
2. The attraction force between molecules is the weak Van der Waals’ force.
Properties of Simple Covalent Molecular Substances - Small Molecules!
1. The intermolecular force between the simple covalent molecules is very weak.
Therefore, covalent compounds have low melting and boiling point.
2. They are also poor conductors of electricity because there are no free electrons
or ions in any state to carry electric charge.
3. Most small molecules will dissolve in a solvent to form a solution.
Physical Properties of Covalent Compounds -
Macromolecular compounds
Macromolecular Compounds
1. The macromolecular compounds have giant, covalent molecules with
extremely large molecular lattices.
2. They have very high melting and boiling points.

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3. They don't conduct electricity — not even when molten (except forgraphite).
4. They're usually insoluble in water.
5. Examples of such macromolecules are diamond, silica and graphite.
Diamond and Silica(Sand)
(3 dimensional structure macromolecular compound - Diamond)
1. A diamondcrystal or a grainof sand is justone giantmolecule.Suchmolecules,because they
are so rigidandstrong,have veryhighmeltingpoints.
2. Each carbon atom formsfourcovalentbondsina veryrigidgiantcovalentstructure,which
makesdiamondthe hardestnatural substance.Thismakesdiamondsideal ascuttingtools.
3. All those strongcovalentbondsgive diamondaveryhighmeltingpoint.
4. It doesn'tconductelectricitybecauseithasno free electrons.
5. Diamondisan allotrope of carbon.Allotropesare differentformsof the same elementinthe
same physical state

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Graphite
(3 dimensional layer structure: graphite)
1. Carbon also occurs in the form of graphite. The carbon atoms form joined hexagonal
rings forming layers 1 atom thick.
2. Graphite is black and opaque.
3. Each carbon atom only forms three covalent bonds, creating sheets of carbon atoms
which are free to slide over each other. This makes graphite slippery, so it's useful as a
lubricant.
4. The layers are held together so loosely that they can be rubbed off onto paper to leave
a black mark — that's how pencils work.
5. Graphite has a high melting point — the covalent bonds need lots of energy before
they break.
6. Only three out of each carbon's four outer electrons are used in bonds, so there are lots
of spare electrons. This means graphite conducts electricity — it's used for electrodes.
Physical Properties of Covalent Compounds - Macromolecular compounds
Macromolecular Compounds
1. The macromolecular compounds have giant, covalent molecules with extremely large
molecular lattices.

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2. They have very high melting and boiling points.
3. They don't conduct electricity — not even when molten (except for graphite).
4. They're usually insoluble in water.
5. Examples of such macromolecules are diamond, silica and graphite.
Diamond and Silica(Sand)
(3 dimensional structure macromolecular compound - Diamond)
1. A diamond crystal or a grain of sand is just one giant molecule. Such molecules,
because they are so rigid and strong, have very high melting points.
2. Each carbon atom forms four covalent bonds in a very rigid giant covalent structure,
which makes diamond the hardest natural substance. This makes diamonds ideal as cutting
tools.
3. All those strong covalent bonds give diamond a very high melting point.
4. It doesn't conduct electricity because it has no free electrons.
5. Diamond is an allotrope of carbon. Allotropes are different forms of the same element
in the same physical state

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Graphite
(3 dimensional layer structure: graphite)
1. Carbon also occurs in the form of graphite. The carbon atoms form joined hexagonal
rings forming layers 1 atom thick.
2. Graphite is black and opaque.
3. Each carbon atom only forms three covalent bonds, creating sheets of carbon atoms
which are free to slide over each other. This makes graphite slippery, so it's useful as a
lubricant.
4. The layers are held together so loosely that they can be rubbed off onto paper to leave
a black mark — that's how pencils work.
5. Graphite has a high melting point — the covalent bonds need lots of energy before
they break.
6. Only three out of each carbon's four outer electrons are used in bonds, so there are lots
of spare electrons. This means graphite conducts electricity — it's used for electrodes.