REVISIONyear 7

CHEMISTRY

Science Department This Revision Guide can be utilised at home or on your iPad.

This electronic book has been made as an additional aid in the revision process. Each topic has been covered with ‘key fact’ pages, questions and suggested revision method. The question sheet is designed to test your revision of the key facts and see if the information has sunk in. Just answering the questions is not an effective revision method.

Please note, that the material provided should be used in conjunction with the boys own classwork and CGP guides distributed in Year 5 and Year 6.

We hope that they will be useful.

Best of luck!

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year 7

REVISIONElements, Compounds and Mixtures

THE ATOMConsists of three different units.

- Electrons (negatively charge and whizzing around the outside) - Protons (positively charged and in the nucleus) - Neutrons (no charge and in the nucleus)

Atoms combine to form molecules and compounds.

THE ELEMENTS

For example, magnesium + oxygen → magnesium oxide

Metal oxides are basic and solids

Non-metal oxides are acidic and gaseous

For example, carbon + oxygen → carbon dioxide

ELEMENTS REACTING IN OXYGEN

SOME KEY ELEMENTSThere are many elements that can be found on The Periodic Table. These are some key elements that you should know. But you should be familiar with the first 20 elements.

COMPOUNDSCompounds are formed when two or more different elements chemically combine. Compounds have different properties to the elements that combine to make them.

NAMING COMPOUNDSTwo elements joined together will have an -IDE ending More than two elements joined together with oxygen being one of them will have an -ATE ending

For example, iron + sulphur → iron sulphide

For example, copper + sulphur + oxygen → copper sulphate

iron + sulphur → iron sulphide

CLASS PRACTICAL

You need to recognise this reaction. It shows that a new substance is formed. Before the reaction iron is magnetic. Iron Sulphide is not magnetic and therefore proves a new substance has been formed.

Look at the observations made during this reaction.

H₂O

Chemical symbols are used to represent compounds. The numbers relate to how many atoms there are in the compound.

Conservation of mass states the mass of the reactants equals the mass of the products. For example, magnesium appears to gets heavier when heated in air because it chemically combines with oxygen to form magnesium oxide (Mg → MgO).

CHEMICAL SYMBOLS

water has two hydrogen atoms

water has one oxygen atom

MIXTURESMixtures are two elements or compounds that are together but not chemically joined.

(See separating substances section when complete)

→Dissolving is a good way to form a mixture. →Mixtures can be easily separated.

GLOSSARY Substance consisting of one type of atom. Substance consisting of two or more different elements chemically combined. A group of atoms chemically joined e.g. water H₂O, oxygen O₂. Substance containing two or more elements or compounds that have not been chemically joined.

Element:

Compound:

Molecule:

Mixture:

POSSIBLE REVISION METHOD - SUMMARY CARDSSummary Cards contain the most important details of a topic. You should try to create a summary of the information, including key words, concepts and diagrams.

QUESTIONSIf you have revised the previous sheets effectively you should be able to answer the following questions without difficulty.

1. What three particles combine to form an atom? 2.What is the name given to the negatively charged particle in an atom? 3.Define an element. 4.Define a compound. 5.Define a mixture. 6.Where do you find non-metals on the periodic table? 7. Copper + Oxygen → 8.Copper + Sulphur + Oxygen → 9. Iron + Sulphur →

10. How can you tell that a reaction is occurring (or has occurred) between Iron + Sulphur in the production of Iron Sulphide? Give two reasons 11. How many carbon atoms are there in a molecule of Glucose?

QUESTIONSIf you have revised the previous sheets effectively you should be able to answer the following questions without difficulty.

C₆ H₁₂O₆

For extra information or help with revision use the

following pages in the KS3 CGP Study Guide, page

35 - 39.

year 7

Making and Testing GasesREVISION

And gases in the air

HYDROGEN GASMaking Hydrogen

Testing for Hydrogen

Reacting a metal with acid will produce a salt and hydrogen gas. Metal + Acid → Salt + Hydrogen

Using a lit splint the hydrogen should ignite with a squeaky pop sound.

CARBON DIOXIDE GASMaking Carbon Dioxide

Reacting a metal carbonate with acid will produce a salt, water and carbon dioxide gas. Metal Carbonate + Acid → Salt + Water + Carbon Dioxide

Testing for Carbon Dioxide

Bubble carbon dioxide through limewater. Limewater turns from clear to milky white.

Another Method for Making Carbon Dioxide:

Thermally decomposing calcium carbonate to produce calcium oxide and carbon dioxide gas.

OXYGEN GASMaking Oxygen

Thermally decompose (heat) potassium permanganate.

Testing for Oxygen

Using a glowing splint plunge into oxygen and it should relight.

COLLECTING GAS OVER WATERIf a gas needs to be collected it should be done over water as shown in the diagram below. Learn the diagram!

VOLUME OF GAS COLLECTEDIf a volume of gas needs to be collected or measured, you can set up your apparatus as shown below - how is it different to the collection over water?

GASES IN THE AIR→Air is a mixture of gases. →It consists of different quantities of a variety of different gases.

To prove the percentage of oxygen you can use the set up shown below. Heat the copper fillings between the syringes to form copper oxide and remove oxygen from the air within the syringes. The syringes should read 100mL at the beginning and 79mL at the end thus showing oxygen is 21% of air.

PERCENTAGE OF OXYGEN IN THE AIR

POSSIBLE REVISION METHOD - REVIEW CARDS (FLASH CARDS)Review Cards pose questions with long answers or facts on the back. Flash Cards can be used to learn key words or definitions

If you have revised the previous sheets effectively you should be able to answer the following questions without difficulty.

QUESTIONS

1. How is Hydrogen made in a lab? 2.How do you test for Hydrogen? 3.How is Oxygen made in a lab? 4.Do you use a lit splint or glowing splint to test for oxygen? 5.What substance is used to test for carbon dioxide? 6.What change is seen in this substance if carbon dioxide is present? 7. Write the word equation for the production of carbon dioxide. 8.Write the word equation for the production of hydrogen.

9.Draw the diagram for the collection of gas over water. 10. Why does gas rise to the top of the test tube when being collected over water? 11.What is the percentage of Nitrogen in the atmosphere? 12. If 100cm³ of air is passed over copper filings which are being heated. After several minutes what will be the volume of air? 13. Why?

QUESTIONSIf you have revised the previous sheets effectively you should be able to answer the following questions without difficulty.

For extra information or help with revision use the

following pages in the KS3 CGP Study Guide, page

64.

year 7

FuelsREVISION

FUELSFuels react with oxygen to release energy. Most fuels contain hydrocarbons. These are compounds of hydrogen and carbon only.

COMPLETE COMBUSTIONComplete combustion releases more energy than incomplete combustion. It requires a plentiful supply of air so that the elements in the fuel react fully with oxygen. The general equation for complete combustion is: hydrocarbon + oxygen → carbon dioxide + water

INCOMPLETE COMBUSTIONIncomplete combustion occurs when the supply of air or oxygen is poor, resulting in carbon monoxide being produced rather than carbon dioxide and producing some carbon (soot) which has not be oxidised. The general equation for incomplete combustion is: hydrocarbon + oxygen → carbon monoxide + water or hydrocarbon + oxygen → carbon + water

THE BUNSEN BURNER

When the air hole is closed the natural gas can only mix with air at the mouth of the chimney. Incomplete combustion occurs as a result. A yellow flame is produced, which transfers less heat energy than the blue flame.

Air hole open

THE BUNSEN BURNER

When the air hole is closed the natural gas can only mix with air at the mouth of the chimney. Incomplete combustion occurs as a result. A yellow flame is produced, which transfers less heat energy than the blue flame.

Air hole closed

If you have revised the previous sheets effectively you should be able to answer the following questions without difficulty.

QUESTIONS

1. How can you test that carbon dioxide was produced? 2.What is the test to determine that water is present?

For extra information or help with revision use the

following pages in the KS3 CGP Study Guide, page

—

year 7

Acids, Alkalis and NeutralisationREVISION

→Have a low pH →Have a sour taste (tartaric acid used in toxic waste sweets!!) →Contain Hydrogen and are used to make Hydrogen in some reactions. →Make Carbon Dioxide in some reactions →Can react to produce Salts Hydrochloric Acid – Chloride Salts Nitric acid – Nitrate Salts Sulphuric Acid – Sulphate Salts etc.

ACIDS

→Have a high pH →Soapy texture (often used in cleaning fluids) →Alkalis are soluble bases (bases which have dissolved) →All alkalis are bases but not all bases are alkalis.

ALKALIS

BASES

→Substances which can neutralise an acid. →When dissolved in water to form a solution are called alkalis →Usually Metal Oxides, Hydroxides or Carbonates e.g. Magnesium Oxide, Sodium Hydroxide.

Used to help identify the strength of an acid or base/alkali. Universal Indicator is used to help show the pH by checking the colour it turns against the colour chart. If an acid is diluted its pH does not change significantly.

THE pH SCALE

When acids and alkalis are combined to form salts. The salt contains the metal from the alkali and part of the acid molecule. The salt depends on the type of acid e.g. sulphuric acid forms sulphate salts.

NEUTRALISATION

ACID + ALKALI SALT + WATER

→Bases are metal oxides or metal hydroxides, e.g. iron oxide and calcium hydroxide. → Alkalis are bases which dissolve in water. They are always metal hydroxides, e.g. potassium hydroxide and sodium hydroxide. → Metals all conduct electricity. Lots of them have names ending in ‘-ium’ although there are a few non-metals which also end in ‘-ium’. They include metals with common names like copper, lead and aluminium. → Metal Carbonates are all metals combined with carbonate groups, e.g. copper carbonate, potassium carbonate and iron carbonate. They are also classified as bases because they neutralise acids, but they react with acids in a different way to metal oxides and metal hydroxides. →Acids all contain hydrogen. The three we need to know are hydrochloric acid, sulphuric acid and nitric acid.

The Rules ITHE REACTIONS OF ACIDS WITH ALKALIS, BASES, METAL CARBONATES AND METALS

Base + Acid → Water + Salt (BAWS) Acid + Alkali → Water + Salt (AAWS) Metal + Acid → Salt + Hydrogen (MASH) Metal Carbonate + Acid → Water + Salt + Carbon Dioxide (MCAWSCD) → A salt is a metal sulphate, metal chloride or metal nitrate

The Rules IITHE REACTIONS OF ACIDS WITH ALKALIS, BASES, METAL CARBONATES AND METALS

Hydrochloric acid makes chloride salts.

Sulphuric acid makes sulphate salts.

Nitric acid makes nitrate salts.

Phosphoric acid makes phosphate salts.

1. Sulphuric Acid + Copper oxide → 2. Nitric Acid + Iron carbonate → 3. Hydrochloric acid + sodium hydroxide → 4. Sulphuric acid + Zinc → 5. Acetic acid + aluminium → 6. _____________ + ____________ → lead nitrate + carbon dioxide + water 7. ______________ + Magnesium → Magnesium chloride + _____________ 8. Nitric acid + ____________ → Calcium __________ + water 9. Zinc oxide + Nitric acid → 10. Magnesium hydroxide + sulphuric acid → 11.Copper + hydrochloric acid →

NEUTRALISATION REACTIONS

POSSIBLE REVISION METHOD - REVIEW CARDS (FLASH CARDS)Review Cards pose questions with long answers or facts on the back. Flash Cards can be used to learn key words or definitions

If you have revised the previous sheets effectively you should be able to answer the following questions without difficulty.

QUESTIONS

1. Is an acid’s pH low or high? 2.What chemical element do all acids contain? 3.Name a household acid. 4.What chemical compound do acids produce in some reactions? 5.What acid produces chloride salts? 6.What acid produces sulphate salts? 7. What is an alkali? 8. Is an alkali’s pH high or low?

9.Name a household alkali. 10. Give two examples of bases. 11.What is the pH scale used for? 12. How do you find the pH of a chemical? (Include all detail!) 13. Does an acid’s ph change much if water is added to it? 14. Write the word equation for neutralisation. 15. What two products are produced in a neutralisation reaction? 16. What are the reactants in neutralisation? 17.What determines which salt is produced in a neutralisation reaction?

QUESTIONSIf you have revised the previous sheets effectively you should be able to answer the following questions without difficulty.

For extra information or help with revision use the

following pages in the KS3 CGP Study Guide, pages

52 - 53 and 55 - 56.