state symbol -IGCSE/ GCSE NOTES

State symbolsThe state symbols are put in a balanced equation to show whether something is a solid, liquid, gas or dissolved in water (aqueous solution).
The symbols for these are:
state
Symbol
Solid
(s)
Liquid
(l)
Gas
(g)
Aqueous
(aq)
Magnesium + oxygen --> magnesium oxide
2Mg{s} + O2{g} --> 2MgO{s}
hydrochloric acid + calcium carbonate --> calcium chloride + carbon dioxide + water
2HCl (aq) + CaCO3 ---> CaCl2(aq) + CO2(aq) + H20(l)
Balanced equations and ionic equations

Ionic equations only show ions which change in a reaction and ignore those which do not change. E.g.word equation
hydrochloric acid + sodium hydroxide --> sodium chloride + water
balanced chemical equation
HCl(aq) + NaOH(aq) ---> NaCl(aq) + H2O(l)
ionic equationH+(aq) + OH-(aq) ---> H2O(l)
E.g. in the electrolysis of sodium chlorideCl-(aq) --> Cl(g) + e-2Cl(g) --> Cl2(g)
Working out formulae from reacting masseselements reacting magnesium chlorinesymbols of elements Mg Clmasses reacting (from experiment) 2.4g 7.1gmolar mass (look up relative atomic 24g/mol 35.5g/molmass in periodic table)amounts (amount = mass/molar mass) 2.4g/24g/mol 7.1g/35.5g/mol = 0.1mol 0.2molratio of atoms (divide by smallest) 1 : 2formula MgCl2
Work out formulae of compounds formed when the following react:56g of iron and 32g of sulphur (Fe =56, S =32)2g of hydrogen and 16g of oxygen (H=1, O=16)14g of lithium and 16g of oxygen (Li=7)32g of copper and 8g of oxygen (Cu=64)6.4g of copper and 0.8g of oxygen.
C2.08 Calculating reacting masses using equationsYou can work out ratio of the masses of products and reactants by simply multiplying the number of moles shown in the equation by the formula mass of each substance.
Example 1: What mass of magnesium oxide can be made from 12g of magnesium? Relative atomic masses are Mg =24, O = 16. equation 2Mg(s) + O2(g) --> 2MgO(s) formula 2*24 1(16*2) 2(24+16)masses =48 =32 =80 reacting 48g of Mg forms 80g of MgOmasses 1g of Mg forms 80/48 g of MgO 12g of Mg forms 12*80/48 g of MgO = 20g
Example 2: What mass of magnesium oxide can be made from 12g of magnesium? equation 2Mg(s) + O2(g) --> 2MgO(s) amounts 2 moles 1 mole 2 moles masses 2*24 1{16*2} 2{24+16} =48g =32g =80g so 48g Mg forms 80g MgO 1g Mg forms 80/48 g MgO 12g Mg forms 12*80/48 g MgO = 20g Also note that the ratio of amounts of reactants and products in the equation above can be written as:
Amount of Mg/amount of O2 =2/1 Or Amount of O2/amount of MgO = 1/2
problem
You decide to travel from London to Delhi for a holiday and hire your own Airbus 319 jet. You fly the 2183 miles to Cairo first and make 9.4 tons of carbon dioxide. After seeing the Pryramids you fly the 1018 miles to Riyadh making 4.5 tons of carbon dioxide. After a brief stop in the Saudi Capital you fly on the 1900 miles to Delhi making 8.1 tons of carbon dioxide. Finally you return to London travelling 4171 miles and releasing 22 tons of carbon dioxide. The jet burns the fuel kerosine C15H32 in the reaction
C15H32 + 23O2 --> 15CO2 +16H2O(a)
How much carbon dioxide was released into the atmosphere during the trip?(b) What mass of kerosine was burnt?(c) What effect does the trip have of the environment?

formulae and equations

Formulae can be worked out from valency.
Valency
atom or ion with that valency
valency 1
hydrogen, group 1 e.g. sodium and potassium, group 7e.g. fluorine and chlorine, ammonium NH4+, hydroxide OH-, nitrate NO3-
valency 2
group 2 e.g. magnesium and calcium, group 6, sulphate SO42-, carbonate CO32-, copper , II Cu2+ iron II Fe2+
valency 3
group 3 e.g. aluminium, group 5, phosphate PO43-, iron III Fe3+
valency 4
group 4 e.g. carbon
naming of ionic compounds
aluminium oxide
valency 3 2
symbols Al O
formula Al2O3

Use valency to work out the formulae of the following compounds: sodium chloride, potassium bromide, magnesium oxide, calcium sulphide, aluminium nitride, calcium iodide, lithium oxide, aluminium chloride, aluminium sulphide, magnesium nitride.

Calculating relative formula massAdd up the relative atomic mass (found in periodic table) of each atom in the compounsds

e.g. Al203 relative atomic masses of Al = 27, O = 16 (found in periodic table). The formula shows 2 atoms of aluminium and 3 atoms of oxygen so:formula mass of = (2*27) + (3*16) =54 + 48 = 102

Work out the relative formula masses of the following: MgO, FeS, O2, H2O, CaBr2, Na2S, CaCO3, NaOH, HCl, (NH4)2SO4. Relative atomic masses Mg=24, O=16, Fe=56, S=32, Ca=40, Br=80, C=12, Na=23, H=1, Cl=35.5.
Simple balanced equationsIt is possible to write balanced equations for reactions. For example substances such as hydrogen and magnesium combine with oxygen. One method to write them is:

Write a word equation first.

Magnesium + oxygen --> magnesium oxide

Write in the formulae of the substances used.

Mg + O2 --> MgO

Balance the equation so that each element has the same number of atoms on each side.

2Mg + O2 --> 2MgO

sodium + oxygen --> sodium oxide

4Na{s} + O2{g} --> 2Na2O{s}(word equation)

hydrogen + oxygen ---> water(formulae)

H2 + O2 -----> H2O(balance) 2H2 + O2 -----> 2H2O

Representing reactions-IGSCE /GCSE CHEMISTRY NOTES

Word equations
If a reaction occurs between magnesium and oxygen, magnesium oxide is produced, here is the word equation for this reaction: -
magnesium + oxygen --> magnesium oxide
Some other examples are:
hydrochloric acid + calcium carbonate --> calcium chloride+ carbon dioxide+ water
sodium + water --> sodium hydroxide + hydrogen
hydrochloric acid + sodium hydroxide --> sodium chloride + water
Write word equations for the reactions in which the following compounds form from a halogen and another suitable element:
hydrogen fluoride, hydrogen chloride, iron III chloride, iron III bromide, sodium chloride, copper chloride.

Formulae
The formula of an element or compound is simply the symbol of each element present and numbers to show how many atoms are present. Carbon dioxide has the formula CO2. This means that it has one carbon atom and two oxygen atoms in each molecule.

substance formula substance formula
methane CH4 bromine Br2
ethane C2H6 hydrogen H2
propane C3H8 ethanol C2H5OH

diamond and graphite / IGCSE/ GCSE CHEMISTRY NOTES

Giant structures with covalent bonds

In giant covalent structures all the atoms are bonded to each other by strong covalent bonds so they have very high melting and boiling points. They do not usually conduct electricity even if in the liquid state. Diamond and graphite are two examples, which are made from carbon atoms. These two different types of the same element are called allotropes.
Diamond: Each carbon atom forms four covalent bonds in a very rigid giant covalent structure.
Diamond:

Graphite: exists as layers of carbon atoms each held in place by three strong covalent bonds. Each layer is held to the one above it by weak bonds.
Physical properties of giant covalent structures

Giant molecular structures have very high melting points because all atoms are held firmly in place by strong covalent bonds. In graphite each carbon atom is held in place by three strong covalent bonds which gives graphite a high melting point. In diamond 4 strong covalent bonds holds each atom in place. This also gives diamond a very high melting point. The four bonds make diamond very hard. Graphite has weak bonds between layers so the layers slip over each other making graphite soft.
They do not usually conduct electricity even when molten because there are no charged particles to carry the current. There are free electrons between layers in graphite so it conducts electricity.
Explaining differences between propertiesSimple molecular substances like water have weak bonds between molecules so melt at low temperatures because little energy is needed to separate the molecules. Giant covalent structures like diamond have strong covalent bonds holding each atom in place. They melt at high temperatures because a lot of energy is needed to break these strong bonds.

chemicalk bonding- ionic bonding/ covalent bonding / igcse / gcse notes

Bonding
Elements forming compounds with chemical bonds
Electron transfer and ionic bondsAtoms have no charge. A charged particle is called an ion. If an atom loses an electron, it becomes a positively charged (+) ion. An ion that is positively charged is known as a cation. If an atom gains an electron, it becomes a negatively charged (-) ion. An ion that is negatively is known as an anion. The negative and positive ions attract each other to form an ionic bond.

Complete the gaps in the text below:_____ have no charge. A charged particle is called an ___. If an atom loses an ________, it becomes a positively charged (+) ion. An ion that is positively charged is known as a ______. If an atom gains an electron, it becomes a negatively charged (-) ion. An ___ that is negatively is known as an anion. The negative and positive ions attract each other to form an _____ bond.

The formation of sodium and chloride io

Draw atoms and ions for lithium, potassium, fluorine, magnesium, oxygen, sulfur and alumin

b Draw diagrams of ionic bonding in LiF, KF, LiCl, NaF, MgCl2, AlF3, MgO, MgS, Na2O and Al2O3.
Physical properties of giant ionic structuresIonic bonds form when metal and non-metal atoms join. A substance with ionic bonding has an ionic structure. Each ion is firmly held in place by strong ionic bonds so they have high melting and boiling points. If melted, charged ions become free to carry an electric current. The ions also become free if dissolved in water so solutions are also electrolytes. The solids are insulators because the ions are not free to move and cannot carry a current. Sodium chloride NaCl, and magnesium oxide MgO are good examples.
Task C1.10 Pick out the substances which are (a) ionic (b) have covalent bonds (c) have high melting points (d) conduct electricity when molten: sodium chloride, sulfur dioxide, magnesium oxide, iron fluoride, carbon dioxide, NaBr, H2O, NH3, Al2O3, KCl.
Covalent bonds and electron sharingNon-metal atoms join using covalent bonds. When a covalent bond is formed, atoms share their electrons. The atoms then have full shells. One covalent bond needs one shared electron from each atom. Each atom involved has to make enough covalent bonds to fill up its outer shell. Sharing electrons is called covalent bonding. Below is a diagram to show hydrogen gas (H2).
Dot and cross diagrams


Draw atoms of F, H, O, N and C.Draw a dot and cross diagram for fluorine F2, hydrogen fluoride HF, water H2O, ammonia NH3, methane CH4, oxygen O2, nitrogen N2, ethene C2H4

Physical properties of simple molecular substances

Simple Molecular Substances have low melting and boiling points and most are gases or liquids at room temperature. This is because of weak forces between the molecules. Molecular substances do not conduct electricity, because there are no ions. E.g. water.Draw diagrams to show how the molecular structures for the following might look: fluorine F2, hydrogen fluoride HF, water H2O, ammonia NH3, methane CH4, oxygen O2, nitroge

WORK SHEET / ELECTROLYSIS / IGCSE / GCSE / OXIDATION AND READUCTION

1.Name the process of the industrial extraction of oxygen
……………………………………………

What is oxidation?……………………………………….

What is reduction?…………………………

Give example for oxidizing

agent…………………………………………….

Give example for reducing agent…………………

2.Complete these reactions
( balance )S+ O2__________
Fe + O2__________
Mg + O2 _____________
Cu + O 2_________
C +O 2 ___________
CH4 + O2_____________

3.Describe an experiment to determine the % of oxygen in air (copper turning )

4.Give the reaction of sulphur dioxide with water…………………………………………….

Give two equations for the reactions in contact process ( impor)
…………………………………………………………….……………………………………………………….

5.Which one is reversible reaction?……………………………………………


6.Describe the laboratory preparation of carbon dioxideGive the equation for reaction……………………………………………………………………………….


7.Give the uses of carbon dioxide…………………………………

8.What is dry ice?……………………………

9.Give two uses of dry ice………………………………………..
10.Give the reaction of nitrogen with oxygen
( 2 equations)………………………………………
11.Give the conditions needed for the rusting of iron

12.Give method for the prevention of rusting

13.How this method work in preventing rusting of ironExplain sacrificial protection. Give example.

14.Sodium can be prepared by electrolysis only were as iron fro blast furnace give your answer (in terms of reactivity)

15.Give the allotropes of sulphur

Name the process by which nitrogen is industrially

extracted………………………………………………………………..

Give one use of nitrogen……………………………………….

16.Why nitrogen is used for protecting dry foods……………………………………………….

Describe the laboratory preparation of ammonia

17.Give the equation for the preparation………………………………………………………………..

18.Give physical properties of ammonia………………………………………………………………………………………

19.ammonia dissolve in water forms …………………………………………
give the equation………………
…………………………
20.Give the uses of ammoniato prepare nitric acidto prepare fertilizer

Give the reaction between sulphuric acid and ammonia ( important)

NH 3 + H2SO4 ----------- (NH4)2 SO4 ( AMMONIUM SULPHATE)


21.Give the reaction between NITRIC acid and ammonia ( important)

NH3+ HNO3 ------- NH 4 NO3( AMMONIUM NITRATE)

22.What are the elements present in NPK FERTILIZER?………………………………………………………..

23.Describe the chemical test for water……………………………………………………………..

24.Describe the physical test for water………………………………………………………………


25.Describe the laboratory preparation of hydrogen

26.Name the gas produced when a metal react with dilute acid…………………………………………………….

27.Give the test for this gas…………………………………………………….

28.Give word equation for the reaction between hydrogen and oxygen…………………………………………………..

29.Give balanced equation for the reaction between hydrogen and

oxygen…………………………………………………..

30.Give one example for transition metal which is used as catalyst…………………………………………………….

31.Iron react with chlorine to form a yellow( brown) color solid
Name it…………………………….

Give equation for the reaction…………………………………………………..

Give the color of ion with sodium hydroxide

Fe2+ …………………Fe3+…………………Cu2+ ………………

32.Name the compounds……………………………………………………..Write down the action of iron over steam.

33.Give the balanced equation ( notes)…………………………………………………………………..

34.Write down the action of iron hydrogen chloride gas Give the balanced equation
ColorCopper oxide-redCopper hydroxide – blueCopper nitrate –greenCopper sulfate- blueCopper carbonate-blackCopper chloride- green


35.Write down the reaction of ammonia with copper (II) ions ( important)………………………………………………………………………………


36.Give the properties of transitional metals( answer given below)
1) variable valency2) colored compounds3) catalytic property


work sheet 2
1,Give example for Fe shows variable valency…………………………………………………………………….


What is reactivity series?


2.Give the order…………………………………………………………………………………


3.What do you know about the reactivity of and displacement reaction?………………………………………………………………………….


4.A copper dipped in silver nitrate solution .5.What is observation that you seeAfter 2hours……………………………………………………..

6.Iron nail dipped in copper sulphate ……………………………………


7.Silver nail dipped ii copper sulphate……………………………………


8.Copper nail in iron sulphate……………………………..(Important portion)Cat ionFlame colorLithium(Li+Sodium (Na+)Potassium( k+)Calcium( ca2+)test for gases oxygen------------------carbon dioxide----------------hydrogenchlorine-----------------------Sulpher dioxide----------------------ammonia--------------------------Test for anionsChloride(Cl-)-----------------------Bromide(Br ---------------------------Iodide (I-)-----------------------Sulphate(so42+)---------------------Sulphite( S2_)-----------------Carbonate(CO32_)------------------Test for cat ionAmmonia (NH4+)-----------------Copper (Cu2+)---------------Iron( Fe2+)-----------------

9.The pure iron get from the furnace has little use only?

10.The pure iron is rustingGive good methods to prevent rusting………………………………….

11.Give the chemical name of rust.………………………..

12.Why not cool air is blown from bottom.Temperature in side furnace get reduced

CHEMISRTY OF ELEMENTS / WORK SHEET / IGCSE / GCSE / HALOGENS /PERIODIC TABLE

Revision sheet

Chemistry of elements1.

In the periodic table the elements are arranged according to the ……………………………. Number

2. In the periodic table the elements are arranged according to the …………………………….

No of particle in the nucleus

3. Give any two property of metal………………………………………………………………………………….

4. Give any two properties of non metal……………………………………...

5. NAME THE FIRST GROUP ELEMENTS……………………………………………..

6. Name the second group elements…………………………………………………….

7. Name the seventh group elements………………………………….

8. Group 1 element are always has a …………………. Charge

9. Group 2 element are always has a …………………. Charge

9. Group 7 element are always has a …………………. Charge

10. Group 6 element are always has a …………………. Charge

11. Element A put in water to produce a gas BAnd an alkali C

12.It will give lilac color to the flameName the element A ……………………

13.Name the gas B ………………………………………….

14.NAME THE ALKALI C ………………………………………

15.Write three things that you see in this experiment

16.What is color change shown by the universal indicator in the solution?………………………………………….

17. Write down the word equation for the above reaction…………………………………………………..

18. Write down the balanced equation for the above reaction…………………………………………………..

19. What is the effect of blue litmus red litmus in the beaker…………………………………………

20. How will you test the gas evolved………………………………

21. Name a non metal for the same period as lithium ………………………..

22. Name another metal in the same period as lithium……………………………..

23. What is similar in the arrangement of electron in alkali metals?…………………………………………….

24. Why diamond and graphite have similar properties………………………………………….

25. Why diamond and graphite have different properties………………………………………….

26.why graphite conducts electricity but diamond not. Why?………………………………………………………………………………………..

27. Give the equation for the burning of graphite in air…………………………………………………………..

28.give the word equation for the burning of magnesium……………………………………………………..

29. give the( halogen) colour and Physical state

30. How will you convert the hydrogen chloride gas into hydrochloric acid

31. A solution in which the hydrochloric acid is dissolved is tested with blue litmus. What do you observe?

32. Hydro choric acid is dissolved in methyl benzene. What do the change in the blue litmus?

33. Describe the laboratory preparation of chlorine from hydro choric acid ( important)…
…………………………………………………………………………………………………..

34.Name the oxidizing agent in this reaction……………………………………

35. Give the test for chlorine…………………………………………………………….

36. Chlorine and bromine have similar properties why?……………………………………………………………………………….

37. Chlorine is passed through a solution of potassium bromide

Name the type of reaction………………………………………….

the solution became red in color. Why?…………………………………………………………………………..

38.Explain why no displacement reaction when we add bromine to potassium chloride …………………………………………………………………………………………
Write the ionic equation for the reaction……………………………………………….

39.Chlorine is bubbled through the potassium iodide solution.
What will be the color of theFinal solution ……………………………………………..

Write down the ionic half equation for the reaction …………………………………

40.What is the color change during the below reaction……………………………………………………H2 + Cl 2___________ 2HCl

reactivity series/ SALT ANAYSIS / IGCSE /GCSE WORK SHEET

work sheet 2


1.Give example for Fe shows variable
valency…………………………………………………

What is reactivity series?

2.Give the order…………………………………

3.What do you know about the reactivity of and displacement reaction?

………………………………………

4.A copper dipped in silver nitrate solution .

5.What is observation that you seeAfter 2hours…………………………

6.Iron nail dipped in copper sulphate ……………………………………

7.Silver nail dipped ii copper sulphate……………………………………

8.Copper nail in iron sulphate……………………………..
(Important portion)

Cat ionFlame color

Lithium(Li+Sodium (Na+)Potassium( k+)Calcium( ca2+)

test for gases oxygen------------------

carbon dioxide----------------

hydrogenchlorine-----------------------

Sulpher dioxide----------------------

ammonia--------------------------

Test for anionsChloride(Cl-)-----------------------

Bromide(Br ---------------------------

Iodide (I-)-----------------------

Sulphate(so42+)---------------------

Sulphite( S2_)-----------------

Carbonate(CO32_)------------------

Test for cat ionAmmonia (NH4+)----------

Copper (Cu2+)---------------

Iron( Fe2+)-----------------

9.The pure iron get from the furnace has little use only?

10.The pure iron is rustingGive good methods to prevent rusting……

11.Give the chemical name of rust.………………………..

12.Why not cool air is blown from bottom.Temperature in side furnace get reduced