Chemistry Form 4 Definition List

1. Element – a substance consists of one type of atom.

2. Compound – a substance consists two or more elements that are chemically bonded

(molecule or ions).

3. Atom – smallest particle of an element.

4. Molecule – a group of two or more atoms.

5. Ion – a positively charged / negatively charged particle.

6. Isotopes – atoms of the same element with same proton number but different nucleon

numbers.

7. Relative atomic mass of an element = the average mass of one atom of an

element/((1/12) x the mass of one carbon-12 atom)

8. Relative molecular mass of an element = the average mass of one atom of an

molecule/((1/12) x the mass of one carbon-12 atom)

9. Molecule formula – compound shows the actual number of atoms of each element that

are present in a molecule of the compound

10. Empirical formula – compound shows the simplest whole number ratio of atoms of each

element in the compound

11. Mole – amount of substance that contains as many particles as the number of atoms in

exactly 12 g of carbon-12 the symbol of mole is mol.

12. One mole – Avogadro constant – 6.02 x 1023

13. Group (Periodic Table) – vertical columns of element (similar chemical properties).

14. Periods (Periodic Table) – horizontal rows of element.

15. Valence electrons – electrons that occupy the outermost shell.

16. Ionic bond – bond formed through the transfer of electrons between atoms of metal and

non-metal to achieve the stable octet electron arrangement.

17. Ionic compound – consist of positive ions and negative ions which are held by strong

electrostatic forces of attraction.

18. Covalent bond – bond formed through the sharing of non-metal electrons to achieve the

stable duplet or octet electron arrangement.

19. Covalent compound (also simple molecular structure) – consists of neutral molecules

which are held by weak intermolecular forces (Van der Waals).

20. Alkali (base) – chemical substance which ionizes in water to produce hydroxide ions,

OH-.

21. Acid – chemical substance which ionizes in water to produce hydrogen ions, H+ or

hydroxonium ions, H3O+.

22. pH – degree of acidity or alkalinity of a solution. Scale ranges from 0 to 14.

23. pH value – measure of the concentration of hydrogen ions, H+.

24. Strong alkali – ionises (dissociates) completely in water to form hydroxide ions, OH- of

high concentration.

25. Weak alkali – ionises (dissociates) partially in water to form hydroxide ions, OH- of low

concentration.

26. Strong acid – ionises (dissociates) completely in water to form hydrogen ions, H+ of high

concentration.

27. Weak acid – ionises (dissociates) partially in water to form hydrogen ions, H+ of low

concentration.

28. Polymer – long chain molecules made up by monomer (repeating unit).

SPM Form 4 – Terminology and Concepts: Chemical Formulae and Equations – Part 1

1. Relative atomic mass, Ar is the atomic mass of an atom when compared to a standard atom

2. Standard atom:

Hydrogen scale: hydrogen is the lightest atom of all and the mass of one hydrogen atom was

assigned 1 unit.

Weakness of Hydrogen scale:

not too many elements can react readily with hydrogen,

the reactive masses of some elements were not accurate,

hydrogen exists as a gas at room temperature and

has a number of isotopes with different masses.

Helium scale: the second lightest atom of all and the mass of one helium atom was assigned 1

unit.

Weakness of Helium scale:

Mass of 1 helium atom = 4 times the mass of a hydrogen atom

So, mass of 1 helium atom = 4 times 1/12 mass of a carbon atom

helium exists as a gas at room temperature and

helium is an inert gas.

Oxygen scale: chose as the standard atom to compare the masses of atoms

Weakness of Oxygen scale:

the existence of three isotopes of oxygen were discovered,

natural oxygen (containing all the three isotopes) as the standard (Chemist) and

used the isotopes oxygen-16 as the standard (Physicists).

Carbon scale: standard atom of comparison internationally.

a carbon-12 atom is 12 times heavier than an atom of hydrogen,

used as the reference standard in mass spectrometers,

exists as a solid at room temperature,

most abundant carbon isotope, happening about 98.89% and

carbon-12 is close to the agreement based on oxygen.

3. Relative molecular mass, Mr of a substances is the average mass of a molecule (two or more

atoms) of the substances when compared 1/12 with of the mass of a carbon-12 atom.

4. Relative formula mass, Fr is for ionic compound which is calculated by adding up the

relative atomic masses of all the atoms.

5. Example:

Relative atomic mass, Ar of helium = 4

Relative molecular mass, Mr of CO2 = 12 + 2(16) = 44

Relative formula mass, Fr of NaCl = 23 + 35.5 = 58.5

Relative formula mass, Na2CO3·10H2O = 2(23) + 12 + 3(16) + 10 [2(1) + 16] = 286

Try to solve some of the examples without looking at the answers. If you can understand this,

then stay tune and log in again for Part 2 of this topic’s notes. If you cannot understand the

examples, try and try and try and try and try again until you are good with it. Till then.

SPM Form 4 – Terminology and Concepts: Chemical Formulae and Equations (Part 2)

Berry Berry Scientist

Italian physicist Amedeo Avogadro (Name at birth: Lorenzo Romano Amedeo Carlo Avogadro)

Born: 9 August 1776

Birthplace: Turin, Piedmont, Italy

Died: 9 July 1856

Best Known As: The guy they named Avogadro’s number after

1. Avogadro constant / Avogadro’s number is 6.02 x 10 23

2. Atomic substances

Elements – all the particles are atoms.

Example: zinc (Zn), sodium (Na), aluminium (Al) and all noble gases, argon (Ar), helium

(He) and neon (Ne).

RAM (Relative Atomic Mass) of  Na = 23

3. Molecular substances

Covalent compounds – the particles are molecules.

Example: carbon dioxide (CO2), water (H2O) and non-metal elements, iodine (I2),

nitrogen (N2) and oxygen (O2).

RMM (Relative Molecular Mass) of I2 = 127 + 127 = 254

4. Ionic substances

Ionic compounds – the particles are ions.

Example: sodium chloride (NaCl), hydrochloric acid (HCl) and potassium iodide (KI).

RFM (Relative Formula Mass) of HCl = 1 + 35.5 = 36.5

5. Avogadro’s Law / Gas Law states that equal volumes of all gases contain the same number

of molecules under the same temperature and pressure.

Example: equal volumes of molecular hydrogen and nitrogen would contain the same

number of molecules under the same temperature and pressure.

6. Volume of gas (dm3) = Number of moles of gas x Molar volume

7. Room temperature and pressure (r.t.p.) = 24 dm3 mol-1 (25°C and 1 atm)

Example: What is the volume of 5.0 mol helium gas at s.t.p.?

Volume of gas = Number of moles x Molar gas volume

= 5.0 mol x 24 dm3 mol-1

= 120 dm3

8. Standard temperature and pressure (s.t.p.) = 22.4 dm3 mol-1 (0°C and 1 atm)

Example: What is the volume of 5.0 mol helium gas at s.t.p.?

Volume of gas = Number of moles x Molar gas volume

= 5.0 mol x 22.4 dm3 mol-1

= 112 dm3

9. Mass (g) = Number of moles x Molar mass

10. Number of particles = Number of moles x Avogadro constant

11. Volume (dm3) = Number of moles x Molar volume

Be sure to copy down all these formulae a few times on paper so that you will have a better

chance recalling it in the future. Copying them onto a card to bring around will be very helpful.

SPM Form 4 – Terminology and Concepts: Chemical Formulae and Equations (Part 3)

Empirical and Molecular Formulae

1. Empirical (simplest ratio of atoms of each element that present in the compound) and

molecular formulae (actual number of atoms of each element that are present in one molecule of

the compound) indicate:

the types of the elements

the symbols of the elements and the ratio of atoms or

moles of atoms of each element in a compound.

2. Molecular formula = (empirical formula)n

n is a positive number

Compound Molecular formula n Empirical formula

Carbon dioxide CO2 1 (CO2) = CO2

Ethane CH3 2 (CH3)2 = C2H6

Propene CH2 3 (CH2)3 = C3H6

Glucose CH2O 6 (CH2O)6 = C6H12O6

Quinine C10H12NO 2 C20H24N2O2

3. Chemical formulae for covalent compounds.

Name Chemical

formula

Number of each element

Nitrogen gas N2 2 nitrogen atoms

Oxygen gas O2 2 oxygen atoms

Ammonia NH3 1 nitrogen atom and 3 hydrogen atoms

Water H2O 2 hydrogen atoms and 1 oxygen atom

4. Cations are positively-charged ions.

Charge Cations Formula

+1 Ammonium ion NH4+

+1 * Copper(I) ion Cu+

+1 Hydrogen ion H+

+1 Lithium ion Li+

+1 * Nickel(I) ion Ni+

+1 Potassium ion K+

+1 Silver ion Ag+

+1 Sodium ion Na+

+2 Barium ion Ba2+

+2 Calcium ion Ca2+

+2 * Copper(II) ion Cu2+

+2 * Iron(II) ion Fe2+

+2 * Lead(II) ion Pb2+

+2 Magnesium ion Mg2+

+2 * Manganese(II) ion Mn2+

+2 Nickel(II) ion Ni2+

+2 * Tin(II) ion Sn2+

+2 Zinc ion Zn2+

+3 Aluminium ion Al3+

+3 * Chromium(III) ion Cr3+

+3 * Iron(III) ion Fe3+

+4 * Lead(IV) ion Pb4+

+4 * Tin(IV) ion Sn4+

* refer to the Roman numerals

5. Anions are negatively-charged ions.

Charge Anions Formula

-1 Bromide ion Br-

-1 Chloride ion Cl-

-1 Chlorate(V) ion ClO3-

-1 Ethanoate ion CH3COO-

-1 Fluoride ion F-

-1 Hydride ion H-

-1 Hydroxide ion OH-

-1 Iodide ion I-

-1 Manganate(VII) ion MnO4-

-1 Nitrate ion NO3-

-1 Nitrite ion NO2-

-2 Oxide ion O2-

-2 Carbonate ion CO32-

-2 Chromate(VI) ion CrO42-

-2 Dichromate(VI) ion Cr2O72-

-2 Sulphide ion S2-

-2 Sulphate ion SO42-

-2 Sulphite ion SO32-

-2 Thiosulphate ion S2O32-

-3 Nitride ion N3-

-3 Phosphate ion PO43-

-3 Phosphite ion PO33-

6. Chemical formulae for ionic compounds

Name Chemical formula Number of

cation

Number of

anion

Zinc chloride ZnCl2 1 Zn2+ 2 Cl-

Copper(II) sulphate CuSO4 2 Cu2+ 2 SO42-

Aluminium sulphate Al2(SO4)3 2 Al3+ 3 SO42-

7. Meaning of prefixes

Prefix Meaning

Mono- 1

Di- 2

Tri- 3

Tetra- 4

Penta- 5

Hexa- 6

Hepta- 7

Octa- 8

Nona- 9

Deca- 10

8. Naming of chemical (non-metal) compounds with Greek numerical prefixes.

Non-metal compound Chemical formula

Carbon monoxide CO

Carbon dioxide CO2

Sulphur dioxide SO2

Sulphur trioxide SO3

Carbon tetrachloride

(tetrachloromethane)

CCl4

Form 4 – Terminology and Concepts: Chemical Formulae and Equations (Part 4)

Chemical Equation

1. Importance of chemical equation:

The types of reactants; the physical conditions; the quantity of reactants and products and stated

in moles.

nA + nB –> pC + pD

2. Reactants are written in the left side of the reaction and products are written in the right side of

the reaction.

Example 1:

Word equation: Sodium hydroxide + sulphuric acid –> sodium sulphate + water

Chemical equation: NaOH + H2SO4 –> Na2SO4 + H2O

Balancing equation: 2NaOH + H2SO4 –> Na2SO4 + 2H2O

Complete chemical equation: 2NaOH + H2SO4 –> Na2SO4 + 2H2O

Example 2:

Word equation: Aluminium + copper(II) oxide –> aluminium(III) oxide + copper

Chemical equation: Al + CuO –> Al2O3 + Cu

Balancing equation: 2Al + 3CuO –> Al2O3 + 3Cu

Complete chemical equation: 2Al + 3CuO –> Al2O3 + 3Cu

Example 3:

Word equation: Nitrogen + hydrogen <–> ammonia

Chemical equation: N2 + H2 <–> NH3

Balancing equation: N2 + 3H2 <–> 2NH3

Complete chemical equation: N2 + 3H2 <–> 2NH3

3. Information obtainable from chemical equations.

i) mass of reactants

ii) volume of reacting gas

iii) mass of products formed

iv) volume of gas produced

Example:

2 cm3 of lead (II) nitrate solution is added to excess of potassium iodide solution.

How many molecules of potassium nitrate will be formed?

[Relative atomic mass: N, 14; O, 16; K, 39; I, 127; Pb, 207; Avogadro's constant: 6.02 x

1023 mol-1]

Step 1: Write a complete chemical equation.

Pb(NO3)2(aq) + 2KI(aq) –> PbI2(s) + 2KNO3(aq)

From the equation, 1 mole of Pb(NO3)2 reacts with 2 moles of KI formed 1 mole PbI2 of

and 2 moles of KNO3.

Step 2: Convert to moles.

No. of moles of Pb(NO3)2

= Mass of Pb(NO3)2 / Relative molecular mass

= 2 / [207 + 2(14 + 3 x 16)]

= 6.04 x 10-3 mol

Step 3: Ratio of moles.

Number of moles of KNO3/ Number of moles of Pb(NO3)2

= 2/1

Number of moles of KNO3

= (2 x 6.04 x 10-3) / 1

= 12.08 x 10-3 mol

Step 4: Convert to the number of molecules of potassium nitrate.

Number of molecules of KNO3

= 12.08 x 10-3 x 6.02 x 1023

= 7.27 x 1021

SPM Chemistry 2010 – Extra Tips and Predictions for Paper4541/3

In previous years, SPM Chemistry Paper 3 (2004-2009) has comprises of 2-3 questions with the last question typically comprise of “Planning of Experiment). Detailed information can be found from the list below:

SPM 2003 – 3 questions (No.3 – Hardness of iron and steel or Resistance to rusting of iron and steel)

SPM 2004 – 3 questions (No.3 - Carbon Compound: Esters)

SPM 2005 – 3 questions (No.3 – Choose one: Alloy or Rate of reaction)

SPM 2006 – 2 questions (No.2 – Vulcanised and Unvulcanised rubber)

SPM 2007 – 2 questions (No.2 – Electrochemical cell)

SPM 2008 – 2 questions (No.2 – Group 1 – Periodic Table)

SPM 2009 – 2 questions (No.2 – Salt – pH)

SPM 2010 – 2 questions

The last question (planning of experiment) of Paper 3 consists of 17 marks.

Based on the analysis, the questions will be ask within the Form 4 or Form 5 syllabus (Can be recommended PEKA experiments or not PEKA experiments) (It is not only Form 4 as rumoured) The question will comprise of the following part such as:

a)      Statement of the problem (2003, 2005, 2007, 2009)b)      Aim of experiment (2004, 2006, 2008)c)      All the variables (2003, 2005, 2006, 2007, 2008, 2009)d)     Statement of the hypothesis (2004, 2006, 2007, 2008, 2009)e)      List of substances and apparatus (2003, 2004, 2005, 2006, 2007, 2008, 2009)f)       Procedure of the experiment (2003, 2004, 2005, 2006, 2007, 2008, 2009)g)      Tabulation of data (2003, 2004, 2005, 2006, 2007, 2008, 2009)

BIT Paper 3 (SPM 2010)

From above analysis, the predicted SPM 2010 last question in Paper 3 is:

a)      Aim of experimentb)      All the variables

c)      Statement of the hypothesisd)     List of substances and apparatuse)      Procedure of the experimentf)       Tabulation of data

Each section the maximum marks will be 3 marks (3 x 6 = 18 marks). But the marks provided is 17 marks, so this would depend on the marking scheme either 1 mark will be an extra point or one of the part (a) or (f) would be 2 marks.

How to answer the question?

a) Statement of the problem: It always must be a question and ended with question mark. Read the question well and you will find it in the hint in the question. Start your statement of the problem with ‘How does manipulated variable affect responding variable?’ or ‘Does increasing/decreasing manipulated variable increase/decrease the responding variable?’

b) Aim of experiment: It always must be a statement and ended with full stop. Start your aim of experiment with ‘To compare … / To investigate … / To study …

c) All the variables: List out all the variables and separate each variable in the following sequence.

Manipulated variable: (axis-x values) Responding variable: (axis-y values)

Constant variable:

d) Statement of the hypothesis: It always must be a statement and ended with full stop. ‘The manipulated variable, the higher/lower/increase/decrease responding variable’

Important note: Must follow the sequence (always start with manipulated variable and follow by responding variable).

e) List of substances and apparatus: Always separate substance and apparatus even though this is in one section. Must list everything completely to get 3 marks!

Substances: (the same meaning with materials in PEKA experiments)

Important note: Solution: try to give the concentration of the solution (always in the range of 0.1 – 1.0 mol dm-3) and concentrated solution (>1.0 mol dm-3)

Example:

0.1 mol dm-3 of hydrochloric acid 0.5 mol dm-3 of nitric acid

1.0 mol dm-3 copper(II) suphate solution

0.5 mol dm-3 NaOH, zinc powder …

Apparatus: try to list as complete as possible (everything that can be reused in the experiment)

Example:

Stop watch measuring cylinder

beaker

retort stand

conical flask

filter funnel

trough

forceps

tongs …

f) Procedure of the experiment: This is the hardest part to get full marks (3 marks). You need to write the procedure as complete as possible which means all steps are to be written in detail. Berry Teacher would recommend the sentence should be written in passive form sentence (same in PEKA) and it can be present or past tense (no penalty). And try to uniform it. From the previous SPM Paper 3 record, there is no penalty if you write in active form sentence but not in PEKA report!

g) Tabulation of data: This is the easiest part to get one mark, as long as you draw a table (empty table / box), you will be given at least one mark. Remember to write unit in the manipulated variable column and responding variable column!