AQA C4.2

102 Pages·2017·2.07 MB·English

by  Ashbee2, Ruth

AQA C4.2
Bonding, Structure and the properties of matter.
Abstract
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Ashbee2, Ruth
[Email address]
Contents
4.2.1 Chemical bonds, ionic, covalent and metallic Page
4.2.1.1 Chemical bonds
4.2.1.2 Ionic bonding
4.2.1.3 Ionic compounds
4.2.1.4 Covalent bonding
4.2.1.5 Metallic bonding
4.2.2 How bonding and structure are related to
the properties of substances
4.2.2.1 States of matter
4.2.2.2 Chemical equations
4.2.2.3 Structure and function of ionic compounds
4.2.2.4 Structure and function of simple covalent
compounds
4.2.2.5 Polymers
4.2.2.6 Giant covalent compounds
4.2.2.7 Metals as conductors
4.2.3 Structure and bonding of Carbon
4.2.3.1 Diamond
4.2.3.2 Graphite
4.2.3.3 Graphene
4.2.2 Bulk and surface properties of matter
including nanoparticles (Chemistry only)
4.2.4.1 ‘Nano’ dimensions
4.2.4.2 Applications of nanoparticles

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4.2.1 Chemical bonds, ionic, covalent and metallic
4.2.1.1 Chemical bonds
There are three types of strong chemical bonds: ionic, covalent and metallic.
 For ionic bonding the particles are oppositely charged ions.
 For covalent bonding the particles are atoms which share pairs of electrons.
 For metallic bonding the particles are atoms which share delocalised
electrons.

Ionic Compounds Covalent Compounds

1. Crystalline solids (made of ions) 1. Gases, liquids, or solids (made of
2. High melting and boiling points molecules)
3. Conduct electricity when melted 2. Low melting and boiling points
4. Many soluble in water but not in 3. Poor electrical conductors in all phases
nonpolar liquid 4. Many soluble in nonpolar liquids but not
in water

Ionic bonding occurs in compounds formed from metals combined with non-metals.
In ionic bonding, the metal atoms lose electrons and non-metal atoms gain them in
order to produce a noble gas electron configuration.
Typical of ionic bonds are those in the alkali halides such as sodium chloride, NaCl.

Covalent bonding occurs in most non-metallic elements.
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Covalent chemical bonds involve the sharing of a pair of valence electrons by two
atoms. These bonds lead to stable molecules if they share electrons because they
can create a noble gas configuration for each atom.
Hydrogen gas forms the simplest covalent bond in the diatomic hydrogen molecule.
The halogens such as chlorine also exist as diatomic gases by forming covalent
bonds. The nitrogen and oxygen which makes up the bulk of the atmosphere also
exhibits covalent bonding in forming diatomic molecules.

Metalic bonding occurs in metallic elements and alloys.
The properties of metals suggest that their atoms possess strong bonds, yet the
ease of conduction of heat and electricity suggest that electrons can move freely in
all directions in a metal. The general observations give rise to a picture of "positive
ions in a sea of electrons" to describe metallic bonding.

Electrostatic forces of attraction.
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The force of attraction between two opposing charges.
Activities:
1. Define ‘electrostatic forces of attraction’.
2. Extended writing: describe why atoms bond in order to obtain a noble gas
configuration/full outer level of electrons.
3. Describe/draw the structure of common atoms and suggest how they could
bond to obtain a full outer level of electrons.
4. Demo the formation of sodium chloride in a fume cupboard.
Questions:
1. What type of bond will form between nitrogen and oxygen?
2. An atom that has lost or gained electrons if called an _________?
3. Draw lines to match up the key words with their definitions and explanations:

Definition Explanation
Key word

Usually occur between non-metal

Type of bonding where atoms share
Ionic bonding atoms. Diatomic molecules are
electrons with each other formed by this type of bonding.

Type of bonding where one atom loses Occurs between metal atoms.
Covalent bonding
electrons and one atom gains electrons Electrons become delocalised and

more free to move.

Type of bonding where a sea of free
Metalic bonding Occurs between a metal and a non-
electrons is created
metal. Atoms become charged and
are attracted to each other.

4. Explain why elements in Group 0 (Group 8) of the periodic table do not form
bonds.
5. Explain why elements in Group 1 react violently with elements in Group 7.
6. Write electron structures to show the ions that would be formed when the
following atoms are involved in ionic bonding. For each one, state how many
electrons have been lost or gained and show the charge on the ions formed.
a. Aluminium
b. Fluorine
c. Potassium
d. Oxygen
Extension: Look at the exam questions. Decide which one is the hardest to answer
and say why. Then answer the hardest question.

Q1.This question is about magnesium.
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(a) (i) The electronic structure of a magnesium atom is shown below.

Use the correct answer from the box to complete each sentence.

electrons neutrons protons shells

The nucleus contains protons and ..................
The particles with the smallest relative mass that move around the
nucleus are called ..................
Atoms of magnesium are neutral because they contain the same
number of electrons and ..................
(3)

(ii) A magnesium atom reacts to produce a magnesium ion.
Which diagram shows a magnesium ion?
Tick ( ) one box.

(1)

(b) Magnesium and dilute hydrochloric acid react to produce magnesium chloride
solution and hydrogen.
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Mg(s) + 2 HCl(aq) MgCl(aq) + H(g)
2 2
(i) State two observations that could be made during the reaction.
1 ...........................................................................................................
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2 ............................................................................................................
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(2)
(ii) In this question you will be assessed on using good English,
organising information clearly and using specialist terms where
appropriate.
Describe a method for making pure crystals of magnesium chloride from
magnesium and dilute hydrochloric acid.
In your method you should name the apparatus you will use.
You do not need to mention safety.
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(6)
(Total 12 marks)

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Q2.This question is about salts.
(a) Salt (sodium chloride) is added to many types of food.
Sodium chloride is produced by reacting sodium with chlorine.
sodium + chlorine sodium chloride
The diagram shows what happens to atoms of sodium and chlorine in this
reaction.
The dots (•) and crosses (×) represent electrons.
Only the outer electrons are shown.

Describe, in terms of electrons, what happens when a sodium atom reacts with a
chlorine atom to produce sodium chloride.
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(3)

(b) Lack of iodine can affect the learning ability of children.
One idea is that salt (sodium chloride) should have iodine added.
(i) Iodine consists of simple molecules.
What is a property of substances that have simple molecules?

Tick ( ) one box.
Have no overall electric

charge

Have high boiling points

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Have giant covalent

structures

(1)
(ii) Which one of the following questions cannot be answered by science
alone?

Tick ( ) one box.
How much sodium chloride is in

food?

What harm does a lack of iodine do?

Should iodine be added to salt in

food?

Give one reason why this question cannot be answered by science alone.
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(2)

(c) A student produced the salt ammonium nitrate by adding an acid to ammonia
solution.
(i) Name the acid used.
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(1)
(ii) Use the correct answer from the box to complete the sentence.

an acid an alkali a salt

Ammonia solution (ammonium hydroxide) is ..................................... .
(1)
(iii) The student added a few drops of a solution which changed colour when
the reaction was complete.
Complete the sentence.
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The solution added is an ............................................................. .
(1)
(d) Farmers buy solid ammonium nitrate in poly(ethene) sacks.
(i) How is solid ammonium nitrate made from a solution of ammonium nitrate?

Tick ( ) one box.
Crystallisation

Decomposition

Electrolysis

(1)
(ii) Why do farmers use ammonium nitrate on their fields?
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(1)
(iii) The properties of poly(ethene) depend on the reaction conditions when it is
made.
State one reaction condition that can be changed when making
poly(ethene).
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(1)
(Total 12 marks)

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