y9 chemistry revision booklet

8/10/2019 Y9 Chemistry Revision Booklet

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Contents

Atoms and elements

Atoms and elements quiz

Compounds and mixtures

Compounds and mixtures quiz

Chemical reactions

Chemical reactions quiz

Rock cycle

Rock cycle quiz


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Atoms and elements

ElementsAn element is a simple substance that cannot be split into anything simpler by chemical reactions. Atomsare the smallest particles of an element that can exist. Atoms of one element are all the same, and aredifferent from atoms of all the other elements.There are over 100 different elements. All the elements are shown in the Periodic Table . Each elementhas a chemical symbol , which is usually one or two letters. A symbol is written with the first letter as acapital, and the second letter is small.

carbon C oxygen O

nitrogen N hydrogen H

gold Au silver Ag

copper Cu aluminium Al

Metals and non-metalsThe properties of a substance are the words that we use to describe it, or measurements that we canmake on it. Metals and non-metals have different properties.

Metals Non-metals

good conductors of heat and electricity poor conductors of heat and electricity

shiny dull

solids with a high melting point (except for mercury) most are solids or gases

found on the left-hand side of the Periodic Table found on the right-hand side of the Periodic Table

three metals are magnetic no non-metals are magnetic

metals can burn to form alkaline oxides non-metals can burn to form acidic oxides

flexible brittle

CompoundsElements can join together to make compounds. The name of the compound tells you the elements thatare in it. Compounds made from two elements always have a name which ends in -ide .

These elements join together to make these compounds

carbon, oxygen carbon dioxidesodium, chlorine sodium chloride

magnesium, oxygen magnesium oxide


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A chemical formula tells you the name and number of atoms in a compound. The smallest particle of manycompounds is called a molecule . Molecules are made up of atoms. Some elements are also made of molecules. For example, a molecule of oxygen contains two oxygen atoms joined together. The formula isO2.

Elements Compounds Mixtures

atoms of helium (He) molecules of carbon dioxide (CO 2) a mixture of helium and oxygen

molecules of oxygen (O 2) molecules of water (H 2O) a mixture of carbon dioxideand oxygen

a lump of carbon (C) a lump of sodium chloride (NaCl) a lump of bronze(an alloy of copper and tin)


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ATOMS AND ELEMENTS QUIZ1. Which of these things is an element?

A salt B waterC oxygen D air

2 The number of chemical elements in the world is:

A 4.B about 100.C about 1000.D over a million.

3 The element that makes up most of the mass of your body is:A oxygen.B carbon.C calcium.D hydrogen.

4 Chemical elements:A are always solids.B are either solids or liquids.C are always gases.D can be solids, liquids or gases.

5 Which of these metals is not a pure element?A goldB copperC silverD bronze

6 The smallest part of an element is called:A an atom. B a molecule.C a compound. D an ion.

7 An element is something that:A can be split up by a chemical reaction.B cannot be split up by a chemical reaction.C is made up of different kinds of atom.D is a mixture of atoms and molecules.

8 The correct way to write the chemical symbol for calcium isA CA B CaC ca D Ca


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Compounds and mixtures

Elements are simple substances which cannot be split up in chemical reactions. Atoms are the smallestparticles of an element that can exist. Atoms of an element are all the same.

Each element has its own chemical symbol. For example, the chemical symbol for oxygen is O.

Some elements have their atoms joined to each other in small groups called molecules . Oxygen is anexample.

A molecule of oxygen consists of two oxygen atoms joined together.

CompoundsElements can join together to make compounds . A compound contains two or more elements joinedtogether. The name of the compound tells you the elements that are in it. Compounds made from twoelements always have a name which ends in -ide.

Many compounds exist as atoms attached to each other in small groups molecules.

A molecule of water.

The chemical formula tells you the numbers of atoms of each element in a compound. Each element inthe chemical formula is shown by its chemical symbol. For example:

A compound always contains the same elements in the same ratio.

The properties of a compound are different from the elements that make it up. For example, hydrogen isan explosive gas and oxygen will relight a glowing splint but water is a liquid which will put fires out.


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Chemical reactionsCompounds can react chemically by mixing them with other chemicals, or by using heat or electricity. Youcan tell that a chemical reaction has occurred if there is a colour change or when a gas is given off.

Most chemical reactions also involve an energy change. This is usually in the form of heat, but can alsoinvolve light being given off, for example, in burning ( combustion ).

In a chemical reaction a new substance is always formed. Most chemical reactions are not easily reversed(they are irreversible ).

Some chemical reactions take place just by mixing. When you make a solid by mixing two liquids, the solidis called a precipitate .

Other chemical reactions need energy to start them off. This energy can be in the form of heat, light orelectricity. When you use energy to split up compounds they are decomposed .

We can write word equations to show a chemical reaction. The chemicals that you start with are called

the reactants . The chemicals at the end are called the products . For example:

magnesium + oxygen magnesium oxide

reactants product

Physical changesIn a physical change no new substance isformed. Melting , evaporating , condensing andfreezing are all examples of physical changes.For example:

MixturesElements and compounds can also be mixed together. A mixture is easier to separate than the elements ina compound. Soil, river water and sea water are examples of mixtures that occur naturally.

Elements and compounds melt and boil at a fixed temperature. Mixtures do not have definite meltingpoints and boiling points .

Air is a mixture of gases most of the air is nitrogen and oxygen. The gases in the air can be separated byfractional distillation .


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The properties of a substance are the words that we use to describe it, or measurements that we canmake on it. Metals and non-metals have different properties.

Metals Non-metals

are good conductors of heat and electricity are poor conductors of heat and electricity (except forcarbon in the form of graphite which conducts electricity)

are shiny are dullare solids, often with high melting points (except formercury)

are mostly solids or gases

are found on the left-hand side of the Periodic Table are found on the right-hand side of the Periodic Table

are sometimes magnetic three metals aremagnetic (iron, cobalt and nickel)

are never magnetic

form basic oxides form acidic oxides

are rigid when thick and bendy when thin are brittle

can be hammered into shape cannot be hammered into shape the solid ones break

Using metalsMetals and non-metals have different uses because of their different properties.

Aluminium is used for power linesbecause it is light and it is a good conductor of electricity.

Iron and steel are used for bridgesbecause they are strong and cheap.

Gold is used for jewellery because it does not corrode and looks nice.

Metals and acidsMany metals react with acids. Some unreactive metals will only react very slowly with strong acids, somewill not react at all. Some metals are more reactive and explode when added to acid.

When a metal reacts with an acid, hydrogen gas is given off. The reaction also produces a compoundcalled a salt.

There are three main types of salt:

Chlorides are made when hydrochloric acid is used.Sulphates are made when sulphuric acid is used.Nitrates are made when nitric acid is used.


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The general equation is:

acid + metal salt + hydrogen

For example:

hydrochloric acid + zinc zinc chloride + hydrogen

We can test for hydrogen by putting a burning splint into a test tube of gas. If hydrogen is present, it willexplode with a squeaky pop.

BasesBases are compounds which react with acids. All metal oxides , metal hydroxides and metal carbonatesare bases. Bases which dissolve in water are called alkalis (e.g. sodium hydroxide).

Metal oxides and hydroxides and acidsA metal oxide or a metal hydroxide reacts with an acid to form water and a salt. This reaction is calledneutralisation .

The general equation is:

acid + metal oxide salt + water(or hydroxide)

For example:

hydrochloric acid + potassium hydroxide potassium chloride + water

sulphuric acid + copper oxide copper sulphate + water

We can check to see if neutralisation has occurred using universal indicator. The pH of the solution getscloser to neutral (pH7).


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Patterns of reactivity

Metals may react with substances around them in the environment such as air,water and acids.

Some metals react very easily or quickly, such as Potassium or Sodium. They are reactive . Other metals donot react very easily and are described as unreactive . The most reactive metals are found on the left-handside of the Periodic Table. Less reactive metals are found in the centre of the Periodic Table.

Some gases are more reactive than others. In the air, oxygen is the most reactive gas. Nitrogen is not veryreactive. When metals react with the oxygen in the air they form oxides .

metal + oxygen metal oxide

The metals that react quickly with air also tend to react with water. When metals react with water theyform hydrogen gas and a metal hydroxide .

metal + water metal hydroxide + hydrogen

The metals that react with water also react very quickly with acids. Some metals that dont react withwater do react with acids. When metals react with acids, they produce hydrogen and a salt .

metal + acid salt + hydrogen

The name of the salt formed depends on the name of the acid:

sulphuric acid makes sulphates nitric acid makes nitrates hydrochloric acid makes chlorides .


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Reactivity SeriesMetals can be arranged in a Reactivity Series . The most reactive metals are placed at the top of the table.More reactive metals can displace less reactive metals from their compounds. In a displacement reaction,the more reactive metal will form a compound, and the less reactive metal is left on its own as the pureelement.For example, iron is more reactive than copper, so it will displace copper from a compound.

iron + copper chloride iron chloride + copper

Zinc is more reactive than iron, so iron will not displace zinc from a compound.

iron + zinc chloride no reaction

You can use displacement reactions to work out the position of a metal in the Reactivity Series. Forinstance, zinc will displace lead from a compound, so we know that zinc is more reactive than lead.

The Reactivity Series can also be used to predict whether reactions will occur.

The reactivity of metals can be linked to their uses. Metals used for construction need to have a lowreactivity, otherwise they will corrode away. Some metals, such as aluminium, have a natural protectiveoxide layer. Others, such as iron, have to be protected from corrosion, e.g. by painting.

Many low reactivity metals have been known for hundreds or thousands of years. They can be extractedby heating their compounds in a fire.

More reactive metals are extracted by electrolysis. This means that they have only been discovered in thelast two hundred years, since the invention of the

electric battery.


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CHEMICAL REACTIONS QUIZ1 When some acid is put onto a piece of metal:

A there is always a reaction which burns a hole in the metal.B there is never a reaction.C some metals will react with the acid and produce bubbles of gas.D there is always a reaction, which produces a powder.

2 Which of the following is the correct way to test for hydrogen gas?A Bubble the gas through limewater.B Bubble the gas through universal indicator solution.C Put a glowing splint into a tube of the gas (the splint will burn brightly).D Put a burning splint into a tube of the gas (the gas will explode with a squeaky pop).

3 If an acid reacts with a metal, the products are:A a salt and water.B a salt and hydrogen gas.C only hydrogen gas.

D a salt, water and carbon dioxide.

4 Which of the following is not needed to make a prediction about the products of a reaction betweena metal and an acid?A general information about the reactions between metals and acidsB information about the properties of the metalC the name of the metal usedD the name of the acid used

5 When some acid is put onto a piece of rock:A it always reacts and gives off a gas.B it reacts if the rock contains a carbonate.C it always reacts explosively and shatters the rock.D it wont react.

6 The best test for carbon dioxide uses:A universal indicator solution.B a burning splint.C litmus paper.D limewater.

7 When an acid reacts with a metal carbonate, the products are:A the metal and carbon dioxide.B a salt and water.C carbon dioxide, water and a salt.D the metal, a salt and water.

8 Which of these is not a sign that a reaction has taken place?A The substance catches fire.B The substance has changed from a solid to a liquid.C A gas is given off.D There is an explosion.

The rock cycle


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The Earth is continually changing. Rocks are weathered and eroded and new rocks are beingformed. The processes which make rocks, weather them and change them are linked together inthe rock cycle .

Sedimentary rocksRock fragments , formed as a result of weathering and erosion, are transported by rivers, and thefragments get worn down. Small rock fragments are called grains . When the water slows down, some of the grains are deposited at the bottom of rivers, lakes or seas, and form sediment .

Layers of sediment collect on the sea bed, and the bottom layers get squashed. The grains of sediment are

forced closer together ( compacted ) and the water is squeezed out from between the grains. Minerals inthe sediment glue the grains of rock together ( cementation ). Eventually, sedimentary rock is formed.The composition of sedimentary rocks varies and depends on the way they were formed. For example,there are different types of limestone chalk is formed from the shells of microscopic animals, coquina isformed from larger shell fragments and oolite is formed from sediments deposited when sea waterevaporated.

If any animals or plants get trapped in the sediment, they may form fossils .


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Igneous rocksMolten rock is called magma . If themolten rock flows out of volcanoes it iscalled lava . Igneous rocks are formedwhen magma cools down.

Lava cools down quite quickly, andforms igneous rocks with small crystals(like basalt ). Magma underground coolsdown much more slowly and formsrocks, like granite , with bigger crystals.

Metamorphic rocksSedimentary or igneous rocks can be changed by heat or pressure into new kinds of rock, calledmetamorphic rocks . Metamorphic rocks have different properties from the sedimentary or igneous rocksthey were made from.


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ROCK CYCLE QUIZ1. The word metamorphic means:

A deposited.B crushed.C changed.D sedimentary.

2 Which of the following statements is true ?A Marble is formed from limestone.B Marble is not a metamorphic rock.C Slate is formed from granite.D Gneiss is formed from marble.

3 Which statement describes some of the ways in which metamorphic rocks are different fromsedimentary rocks?A Metamorphic rocks do not contain crystals and are very porous.B Metamorphic rocks are softer, more porous and have large grains.

C Metamorphic rocks may be harder, less porous and have crystals which may be lined up.D Metamorphic rocks are softer, less porous and may contain clear fossils.

4 Metamorphic rocks are formed by the effects of:A the high pressure and low temperature inside the Earth.B the high pressure and high temperature inside the Earth.C the low pressure and high temperature inside the Earth.D the low pressure and low temperature inside the Earth.

y9 chemistry revision booklet

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