Name:_____________________________ (
)
Class:__________ Date:___________
WORKSHEET
Chemical Bonding
6.1
The Stable Electronic Configuration of a Noble Gas
1. Noble gases
•
Elements that belong to __________ of the Periodic Table.
•
They are _________ (__), _________ (__), ________ (__), _________ (__), and
________ (__).
•
They are __________ and _____________.
•
They exist as ____________________ in nature.
2. The noble gases have ______ and _____________ outer shells.
•
Helium has a __________ configuration.
•
All other noble gases have an __________ configuration.
3. Atoms of most other elements are reactive because they do not _____________________
____________________.
4. Atoms of these elements ________, ________ or ________ outer electrons to attain the
______________________________ and form _____________ or _____________.
5. Atoms ________ or ________ electrons to form substances with ionic bonding.
6. Atoms ________ electrons to form substances with covalent bonding.
6.2
Forming Ions
1. An atom ________ or ________ electrons to form ions. Ions are __________ particles
because they do not have equal numbers of __________ and __________.
2. Atoms ________ electrons to form positively-charged ions called __________.
1
Example: Formation of a sodium ion
sodium atom ______
_____ outer electron(s)
2, 8, 1
__________
Charge on sodium ion = ___p + ___e
= (____) + (____)
= _____
Example: Formation of a calcium ion
calcium atom ______
____ outer electron(s)
2, 8, 8, 2
__________
Charge on calcium ion = ___p + ___e
= (____) + (____)
= _____
3. Common cations and their charges:
Metallic
element
Electronic
configuration of atom
sodium
2, 8, 1
potassium
2, 8, 8, 1
calcium
2, 8, 8, 2
magnesium
2, 8, 2
aluminium
2, 8, 3
2
Formula of
cation
Electronic
configuration of cation
4. Atoms ____________________ to form negatively-charged ions called __________.
Example: Formation of a chloride anion
chloride atom _____
_______ electron(s)
2, 8, 7
__________
Charge on chloride ion = ___p + ___e
= (____) + (____)
= ___
Example: Formation of an oxide ion
oxygen atom _____
______ electron(s)
2, 6
__________
Charge on oxide ion = ___p + ___e
= (___) + (___)
= ____
5. Common anions and their charges:
Non-metallic
element
Electronic
configuration of atom
chlorine
2, 8, 7
fluorine
2, 7
oxygen
2, 6
sulfur
2, 8, 6
3
Formula
of anion
Electronic
configuration of anion
6.3
Ionic Bonds: Transferring Electrons
1. Ionic bonds occur between metals and non-metals.
Examples of metals:
Examples of non-metals:
2. In the formation of an ionic bond, the metal atom __________ outer electrons to the nonmetal atom. __________ ions (cations) and __________ ions (anions) are formed.
3. The oppositely charged ions are held together by strong ______________________________
called ionic bonds.
4. We can show the formation of an ionic bond by a ____________________ diagram, where
•
__________ (__) represent the electrons of _____ atom;
•
__________ (__) represent the electrons of ________atom.
Steps Involved in the Formation of an Ionic Compound
Example: Sodium chloride
(a)
The sodium atom loses ______ valence electron to the chlorine atom.
Na → __________
Cl + e− → _______
Na atom
Cl atom
Na+ ion
Cl– ion
(______)
(_______)
(_______)
(_______)
(b)
The electronic configuration of Na+ is the same as that of the noble gas _____.
(c)
The electronic configuration of Cl− is the same as that of the noble gas _____.
(d)
Formula of compound formed: _______
4
NOW TRY THESE ON YOUR OWN!
Ionic Bonding between Sodium and Sulfur
Na atom
(2, 8, 1)
S atom
(2, 8, 6)
________
________
________
________
Name of compound: __________________
Formula of compound: _________
Ionic Bonding between Magnesium and Oxygen
________
________
________
________
________
________
Name of compound: __________________
Formula of compound: _______
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________
________
Chemical Formulae of Ionic Compounds
1. Give the names of the following ionic compounds:
Chemical
formula
NaCl
Chemical
formula
ZnSO4
Name
CaO
KNO3
CO2
Li2CO3
Mg(OH)2
Na3PO4
Name
2. When writing the chemical formula of an ionic compound, the positive charges must
__________ the negative charges.
3. The formula of an ionic compound is constructed by _____________ the charges on the
positive and negative ions. All the positive charges ____________________ all the
negative charges in an ionic compound.
•
For example, magnesium forms Mg2+ ions with a charge of ____. Chlorine forms Cl–
ions with a charge of ____. There must be ____ Cl– ions to balance out the _____
positive charges of Mg2+. Hence, the chemical formula of magnesium chloride is
__________.
4. The chemical formula of an ionic compound can be deduced using the following steps:
(a) Write down the ions with the charges, e.g. Xm+Yn–.
Xm+
Yn–
Xn
Ym
(b) Move the values m and n diagonally (without the charges).
The chemical formula is ________.
5. Write the chemical formulae of the following ionic compounds:
Name
Chemical
formula
Name
Lead(II) bromide
Silver sulfate
Copper(II) oxide
Calcium nitrate
Iron(III) hydroxide
Lithium hydride
Sodium hydrogen
carbonate
Ammonium carbonate
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Chemical
formula
6.4
Structure and Physical Properties of Ionic Compounds
Structure of Ionic Compounds
1.
Ionic compounds form ___________________________ also known as crystal lattices.
2.
In sodium chloride, millions of sodium ions and chloride ions are held together by ionic
bonds in a _________________ and __________ manner.
3.
Each sodium ion is surrounded by ____________ ions.
4.
Each chloride ion is surrounded by ____________ ions.
Cl−
Na+
5.
The ratio of sodium ions to chloride ions is _____.
6.
Hence, the formula of sodium chloride is _______.
Physical Properties of Ionic Compounds
1. Ionic compounds have very high ______________________________ because a large
amount of energy is required to overcome the strong forces of attraction between ions in
the crystal lattice.
2. Ionic compounds are usually soluble in _________ but insoluble in __________________.
3. Ionic compounds conduct electricity in the _________ and _________ states because the
ions are ___________________________ in these states.
4. Ionic compounds do not conduct electricity in the solid state because the ions are
____________________________________.
7
6.5
Covalent Bond: Sharing Electrons
1. Covalent bonding involves the ___________________________ with no transfer or
movement of electrons between two atoms. _____________ are formed, not ions.
2. This type of bonding occurs when _____________ atoms join together so as to achieve
the stable electronic configuration of a ______________.
Molecules of Elements
1. Hydrogen
(a) Each hydrogen atom has ________________ in its outer shell. This means that each
hydrogen atom needs _____ additional electron to achieve a stable _________
configuration.
(b) By sharing electrons, each hydrogen atom has __________________ in its outer shell.
Thus, each atom achieves the stable _________ configuration.
(c) This shared pair of electrons forms a ___________________________. The hydrogen
molecule has two atoms and is _________.
H
× H
⚫
2. Chlorine
(a) Each chlorine atom has _________ outer electrons. This means it is _____ electron
short from the stable noble gas structure. It achieves stability by ______________
electron with another chlorine atom.
(b) This shared pair of electrons forms a _________ covalent bond and is the reason why
the chlorine molecule has two atoms and is _________.
(c) The chemical formula of chlorine gas is ____.
(d) Complete the ‘dot and cross’ diagram of the chlorine gas molecule below.
×
⚫
Cl
Cl
8
3. Oxygen
(a) If two pairs of electrons are shared in order to achieve the noble gas structure, then a
___________ covalent bond results. This occurs between atoms in oxygen gas.
(b) The chemical formula of oxygen gas is ____.
(c) Complete the ‘dot and cross’ diagram of an oxygen gas molecule below.
O
O
4. Nitrogen
(a) If three pairs of electrons are shared in order to achieve the noble gas structure, then a
_________ covalent bond results. This occurs between atoms in nitrogen gas.
(b) The chemical formula of nitrogen gas is ____.
(c) Draw the ‘dot and cross’ diagram of a nitrogen gas molecule below.
Molecules of Compounds
1. When atoms of different elements are joined together by covalent bonding, a
____________ compound or ____________ compound is formed.
2. Water
(a) Water is made up of two elements — ___________ and ___________.
(b) In a water molecule, an oxygen atom shares _____ of its outer electrons with _____
hydrogen atoms. ______ single O–H bonds are formed.
(c) The chemical formula of water is ______.
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(d) Draw the ‘dot and cross’ diagram of a water molecule below.
3. Methane
(a) Methane is made up of two elements — _________ and ___________.
(b) A carbon atom shares its ______ outer electrons with ______ hydrogen atoms. ______
______________ bonds are formed.
(c) The chemical formula of methane is _____.
(d) Draw the ‘dot and cross’ diagram of a methane molecule below.
4. Carbon dioxide
(a) Carbon dioxide is made up of two elements — carbon and oxygen.
(b) A carbon atom shares its ______ outer electrons with ______ oxygen atoms. _______
_____________ bonds are formed.
(c) The chemical formula of carbon dioxide is _____.
(d) Draw the ‘dot and cross’ diagram of a carbon dioxide molecule below.
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6.6
Structure and Properties of Covalent Substances
1. Most covalent substances exist as __________________.
2. Atoms in the molecules are held by ________________________.
3. Molecules are held together by weak __________________ forces of attraction.
Melting and Boiling Points
1. __________________ is required to overcome the weak intermolecular forces between
the molecules.
2. Thus, covalent substances have _________ melting and boiling points.
3. Covalent substances are usually _________ or ____________ liquids at room temperature
and pressure.
Electrical Conductivity
1. Most covalent substances _________ conduct electricity in _________ state.
2. This is because covalent substances have no ___________________________ in their
solid, liquid or gaseous states.
3. However, there are some exceptions:
•
Solid carbon in the form of ____________ contains __________________.
•
__________________, __________________ and ____________ form ions when
dissolved in water.
Solubility
1.
Covalent substances are usually _____________ in water.
2. However, some covalent substances are _________ in water, for example alcohol and
sugar.
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3. Covalent compounds are usually soluble in __________________ such as _________,
______________ and _________.
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