NATIONAL QUALIFICATIONS CURRICULUM SUPPORT
Chemistry
Summary Notes for Units 1–3
[INTERMEDIATE 1]
First published 2003
Electronic version 2003
© Learning and Teaching Scotland 2003
This publication may be reproduced in whole or in part for educational purposes by educational establishments in Scotland provided that no profit accrues at any stage.
Acknowledgements
Learning and Teaching Scotland gratefully acknowledge this contribution to the National Qualifications support for Chemistry. The help of David Lindsay, supported by Grampian Education–Business Partnership, Douglas Buchanan and Don Sutherland in the preparation of this publication is acknowledged with thanks.
contents
Introduction iv
Unit 1: Chemistry in action
1a Substances 1
1b Chemical reactions 7
1c Bonding 11
1d Acids and alkalis 15
Unit 2: Everyday chemistry
2a Metals 23
2b Personal needs 31
2c Fuels 33
2d Plastics 43
Unit 3: Chemistry and life
3a Photosynthesis and respiration 49
3b The effect of chemicals on the growth of plants 53
3c Food and diet 56
3d Drugs 62
Answer section
Unit 1: Chemistry in action 65
Unit 2: Everyday chemistry 86
Unit 3: Chemistry and life 112
Introduction
The material for this pack has been produced to support learning and teaching for Intermediate 1 Chemistry. The summary sheets are designed to check students’ understanding of the different topics in the course and when correctly completed should prove to be a valuable revision aid for both the end-of-unit NAB tests and the external examination. While the tasks may be carried out by students working on an individual basis, it is suggested that it would be more effective for students to work in groups.
With an appropriate selection of sheets and minor adaptation where necessary, the sheets can also be used by students who are studying Chemistry at Access 3 level.
The answer section at the back of the pack shows correct answers in bold italic type. Alternative answers that are also acceptable are shown with an asterisk.
SUMMARY NOTES (INT 1 CHEMISTRY) 63
© Learning and Teaching Scotland, 2003
CHEMISTRY IN ACTION
UNIT 1
Unit 1a Substances
Elements (i)
Everything in the world is made from about one hundred …………………… . Each one has a name and a …………………… that consists of one or two letters. The first letter is always a …………………… letter (upper case) and the second letter is always lower case (a small letter), e.g. the symbol for carbon is ……… but the symbol for …………………… is Ca. The symbol for some elements is based on the Latin name, e.g. the symbol for potassium (kalium) is ……… and the symbol for …………………… (natrium) is Na.
Chemists have arranged elements
in the ……………………
…………………… .
Most elements are solid at room temperature, e.g. …………………… and …………………… . The two elements that are liquid at room temperature are …………………… and …………………… .
Some elements are gases at room temperature, e.g. …………………… and …………………… .
Elements can be classified as …………………… and non-metals.
There are many more …………………… than …………………… .
The metals are found to the …………………… side of the zig-zag line in the Periodic Table. Some elements, including …………………… , …………………… and …………………… have been known for a long time. The most recently …………………… elements have been made by scientists. These elements are found after uranium at the …………………… of the Periodic Table.
Elements (ii)
Elements in the same …………………… of the Periodic Table show
similar chemical properties, e.g.
sodium, …………………… and
…………………… are all stored under
oil because they are very
…………………… .
Elements are used for many things.
Some examples of everyday uses of elements are shown in the table.
Element / UseAluminium / …………………………………………………………
Chlorine / …………………………………………………………
Zinc / …………………………………………………………
Carbon / …………………………………………………………
Iron / …………………………………………………………
Argon / …………………………………………………………
Compounds and mixtures
A …………………… is a substance that is made up of two or more elements joined together, e.g.
+ ®
iron sulphur iron sulphide
Compounds with a name ending in ‘-ide’ contain the two elements indicated, e.g. the compound that contains calcium and oxygen is called
…………………… …………………… .
Similarly, sodium chloride contains
…………………… and …………………… .
The name ending ‘-ite’ or ‘-ate’ indicates the additional element …………………… in the compound, e.g. potassium sulphite and potassium sulphate both contain potassium, …………………… and …………………… .
When two or more substances come together without reacting, a
…………………… is formed. Air is a mixture of gases, approximately 80% …………………… and 20% …………………… .
The test for …………………… is that it relights a glowing splint.
A glowing splint does not …………………… in air because there is not enough oxygen.
Solutions
A solution is formed when a substance …………………… in a liquid.
+ ®
copper
sulphate
water copper
sulphate
solution
A substance that dissolves in a liquid is …………………… ; a substance which does not dissolve is …………………… .
A solution is …………………… if more liquid is added to it.
A …………………… solution has a lower concentration of dissolved substance than a …………………… solution.
A …………………… solution is one in which no more substance can be dissolved.
The gas which is dissolved in some drinks to make them fizzy is
…………………… …………………… . The test for carbon dioxide is that it turns …………………… …………………… milky.
The substance that dissolves in the liquid can be a …………………… , a liquid or a gas, e.g. sugar is a solid that dissolves in water, alcohol is a …………………… that dissolves in water and sulphur dioxide is a …………………… that dissolves in water.
In some places, to kill bacteria,
…………………… is added to our drinking
water. To prevent tooth decay, sodium
…………………… is added.
Compounds of …………………… , which can get into drinking water from old pipes, can be harmful to health.
Hazards (i)
Regulations on the use of chemicals exist to ensure a …………………… working environment for everyone who comes into contact with chemicals at work.
Simple …………………… warning symbols, which can be easily recognised, are used to identify the potential dangers of all chemicals.
Hazard symbols are on road tankers
to indicate dangers in the event of
…………………… .
This shows that the chemical is ……………………
(a poison).
Taking or eating these chemicals would make you feel very …………………… and may even cause death.
This shows that the chemical is …………………… (sometimes called caustic).
These chemicals can cause severe …………………… to the skin, as well as holes in some metal objects.
This shows that the chemical is …………………… (sometimes called inflammable, which is the same thing).
Flammable chemicals catch fire and …………………… very easily.
Hazards (ii)
This shows that the chemical is an …………………… or harmful chemical.
Chemicals with this warning symbol can make you feel very …………………… by affecting your skin or organs.
In many cases your …………………… or breathing system can be badly damaged by these chemicals.
This shows that the chemical is …………………… .
As you might expect chemicals with this warning symbol can …………………… !
This shows that the chemical is …………………… .
Exposure to …………………… can be harmful and may lead to cancer. This is why hospital staff in the …………………… department will wear special (and very heavy) clothes, or they will stand behind a protective screen.
Unit 1b Chemical reactions
Identification (i)
All chemical reactions involve the formation of one or more …………………… substances. Chemical reactions can be identified by …………………… in the appearance of substances, including changes in colour.
Chemical reactions can also be identified by a …………………… being given off or a …………………… (precipitate) forming on mixing two solutions.
Some examples of changes that can be observed during chemical …………………… are shown in the table.
Chemical reaction / Evidence of a reaction taking placeMaking toast / …………………………………………
Magnesium with acid / …………………………………………
Iron rusting / …………………………………………
Chemical reactions can also be identified by …………………… changes that take place, e.g. when an alkali reacts with an acid, nothing is seen but the test-tube becomes …………………… because energy is produced, showing that a chemical reaction is taking place.
Identification (ii)
Some examples of the wide variety of …………………… reactions that occur in the world around us are shown in the table.
Everyday chemical reactions…………………………………………………………………………………
…………………………………………………………………………………
…………………………………………………………………………………
Speed of reactions
The speed of a chemical reaction both in the laboratory and in our everyday life can be affected by changes in …………………… size, …………………… of reactants and …………………… of reactants.
Decreasing the particle size …………………… the speed of reaction; decreasing the concentration …………………… the speed of reaction; increasing the temperature …………………… the speed of reaction.
A substance which speeds up a reaction but is not used up by the reaction is called a …………………… . One example of an everyday use of a …………………… is shown in the table.
Catalyst / Everyday use………………… / ……………………………………………………
Catalysts which affect reactions in living things are called …………………… .
They are used in everyday life.
Some examples of everyday …………………… of enzymes are shown in the table.
Enzyme / Everyday use………………… / ……………………………………………………
………………… / ……………………………………………………
………………… / ……………………………………………………
Word equations
In a chemical reaction, the starting substances are called the …………………… and the new substances that are formed are called the …………………… .
A short-hand way of representing a chemical reaction is by a word
…………………… .
Consider, for example, the reaction of paraffin with oxygen to form water and carbon dioxide.
The reactants are …………………… and …………………… .
The products are …………………… and ………………. ………………… .
The word equation for the reaction of sodium with water to form hydrogen and sodium hydroxide is:
…………………… + ……………………
¯
…………………… + …………………… ……………………
Another word equation is:
ammonia + oxygen ® nitrogen + water
This word equation describes the reaction between …………………… and …………………… to form …………………… and …………………… .
In a word equation:
• the …………………… sign means and
• the …………………… means changes into
• the reactants are always written to the …………………… side of the arrow and the products are always on the …………………… side of the arrow.
Unit 1c Bonding
Molecules and ions (i)
Every element is made up of very small particles called ……………………
An …………………… is a substance that is made up of atoms of only one kind.
A silver ring contains millions of
…………………… that are all the same.
Every atom in an iron nail is an atom of iron
and all atoms of iron are the …………………… .
But an iron atom is …………………… in size and mass from a silver atom.
Each …………………… in the Periodic Table contains a different kind of atom. As well as its own name, each element has its own number, called the …………………… number.
The atomic number for potassium is ……… and the element with the atomic number of 92 is called …………………… .
When scientists make new elements, they make new kinds of atoms, i.e. atoms with a …………………… atomic number from all the rest.
Molecules and ions (ii)
A …………………… is a group of atoms (two or more) joined together.
The joins between the atoms are called …………………… .
Some elements and compounds are made up of …………………… ,
e.g. iodine is an ……………………
made up of molecules
and water (hydrogen oxide)
is a ……………………
made up of molecules.
The bonds inside the molecules are …………………… bonds.
The bonds between the molecules are …………………… bonds.
Molecules and ions (iii)
Ions are atoms that have a …………………… .
There are two types of ion, one with a …………………… charge and the other with a …………………… charge.
The bonds holding the oppositely charged ions together are …………………… .
Some compounds are made up of
…………………… , e.g. common
salt (sodium chloride).
The sodium ion (symbol Na+) has a …………………… charge.
The chloride ion (symbol Cl–) has a …………………… charge.
Substances like sodium chloride that are made up of ions are called …………………… compounds.
Formulae – using models
The chemical …………………… indicates the number of atoms of each element in a molecule of the substance, e.g. the chemical formula O2 shows that there are ……… oxygen atoms in the molecule, the chemical formula CH4 shows that there is …………………… carbon atom and ……… hydrogen atoms in the molecule.
One way of working out the chemical …………………… for a substance is by looking at models or pictures of molecules.
has the chemical formula ………
has the chemical formula ………
This compound has the chemical formula ………
while has the chemical formula ………
Formulae – using prefixes
Some compounds have a …………………… at the start of the name that enables us to write the chemical formula directly from the name.
Prefix / Meaning / Name / Formula……… / 1 / Carbon monoxide / ………
……… / 2 / …………………… …………………… / CO2
Tri / ……… / …………………… …………………… / SO3
Tetra / ……… / Silicon tetrachloride / ………
So will have the chemical formula ………
phosphorus trihydride
Unit 1d Acids and alkalis
The pH scale
The ……… scale is used to measure the acidity (or alkalinity) of a chemical.
The chemical must be dissolved in water, i.e. it must be a
…………………… for the pH to be measured.
The pH of a solution is usually measured using pH
…………………… or …………………… indicator.
The pH is found by …………………… the colour of the
paper or indicator with a colour chart.
A pH …………………… can be used to find the pH of a
solution without the need to match with a colour chart.
The pH scale ranges from pH number ……… up to pH
number ……… . Solutions that have a pH of below 7 are
…………………… ; solutions that have a pH above 7 are
…………………… .
The pH of water and …………………… solutions is 7.
The lower the pH of an acid, the …………………… the acidity; a solution with a pH of 2 is …………………… acid than a solution with a pH of 6.