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1 | P a g e M O D U L K I M I A T I N G K A T A N 4

CHAPTER 2: THE STRUCTURE OF ATOM

1. The graph below shows the change in temperature with time when a matter in solid

state was heated.

By referring to the graph above, complete the table below.

Point States of matter Explanation in terms of energy change andmovement of particles

A to B

Heating causes the particles to «««««««««..

more energy and vibrate «««««««««.. The

temperature of the substance and the kinetic energy

«««««««««««««

B to C

Continuous heating does not cause the temperature of

the substance to increase. The energy absorbed is

used to ««««««««««« the forces of

attraction between the «««««««««. The

constant temperature is called the «««««««..

««««««««««««««««..

C to D

Continuous heating causes the temperature of the

liquid to ««««««««««« The particles move

«««««««««. Because their kinetic energy is

««««««««««««««..

Tem erature/ C

A

B

C

D

Time/s




1H1

21Sc45

2He4

3Li

7

4Be

9

5B

11

6C

12

7N

14

8O

16

9F

19

10Ne

20

11Na23

12Mg24

13Al27

14Si28

15P31

16S32

17Cl35

18Ar 40

19K

39

20Ca

40

21Sc

45

By referring to part of the Periodic Table of E lement above, complete the table below.

Element Sym olProtonnum er

No. of neutrons

Nucleonnum er

No. of electrons

Standardrepresentation

Scandium

Aluminium

Argon

Beryllium

Boron

Calcium

Carbon

Chlorine

Fluorine

Helium

Hydrogen

Lithium

Magnesium

eon

itrogen

Oxygen

Phosphorus

Potassium

Proton number

Nucleon number




ISOTOPES AND THEIR IMPORTANCE

Fill in the blanks.

1. Isotop merupakan atom-atom berbe a bagi unsur SAMA yang mempunyai nom or

proton ___________________ tetapi nom or nukleon ______________________

2. Complete the table below:

ElementNum er of isotopes

Sym ol of isotopes

Num er of protons

Num er of electrons

Num er of neutrons

Name of isotope

Hydrogen 3

H 1

1 1

1 Hydrogen-2

1 2

Oxygen 3

O16

8 8 8 Oxygen-16

8 9

O18

8

Carbon 3

6 Carbon-12

6 7

C 14

6 6 8

Chlorine 2Cl

35

1717

17 20

Bromine 235 Bromine-80

35 35 Bromine-81

3. For each of the isotope listed below , state one of its uses.

a Gamma rays of Cobalt-60: «««««««««««««««««««««««««.

b . Carbon-14: «««««««««««««««««««««««««««««««..

c . Phosphorus-32: «««««««««««««««««««««««««««««..

d . Sodium- 24: «««««««««««««««««««««««««««««««

e . Iodine -131: ««««««««««««««««««««««««««««««««




S S E E

Fill i t e lanks and mplete t e table bel .

. Electrons are filled in specific shells, star ting ith the shell nearest to the nucleus of the atom. E ery shell can be filled only ith a cer tain number of electrons.

For the elements ith proton number to 20

The first shell can be filled ith a maximum of . electrons

The second shell can be filled ith a maximum of . electrons

The third shell can be filled ith a maximum of .electrons

2. raw the electron arrangement of a sodium atom,23

11 Na in the box and complete the

table below

3. Val l are electrons in the .. shell of a neutralatom.

. Identif y the number of alence electronsin these atoms according to its electron arrangement.

m Element Electron rrangement mber of alence electrons

xygen 2.

Aluminium 2. .3

hlor ine 2. .

Neon 2.

Potassium 2. . .

agnesium 2. .2

Number of protons

Number of electrons

Number of neutrons

Proton number

Nucleon number

Electron arrangement

Use µx¶ as symbol f or

electrons. raw the

maximum number of

electrons in each shell.




CHAPTER : CHEMICAL FORMULAE AND E UATIONS

A RELATIVE ATOMIC MASS (RAM) AND RELATIVE MOLECULAR MASS (RMM)

Relative atomic mass of an element , Ar

= The average mass of an atom of the element

1/12 x the mass of an atom of carbon -12

Example: Ar of C=12 Ar of O=16 Ar of Mg=24

Relative molecular mass of a su stance, M r

= The Average mass of a molecule of the substance

1/12 x the mass of an atom of carbon-12

Calculating Relative molecular mass,M r Mr = The sum of Ar of all atoms present in one molecule

Example:

Mr of Water, H2O = 2 1 + 16 = 18

Mr of Carbon dioxide, CO 2 = 12 + 2 16 = 44

For ionic substance , Relative formula mass , F r

= The sum of A r of all atoms present in the formula

Example:Fr of Magnesium oxide, MgO = 24 + 16 = 40Fr of Sodium chloride, aCl = 23 + 35.5 = 58.5

1. Calculate the relative formula masses of the following ionic compounds in the table.

Substance Compound formula Relative formula mass, Fr

Potassium oxide K2O 2 39 + 16 = 94

Aluminium sulphate Al2 SO4 3 2 27 +3[32+4 16 ]=342

2 Hydrogen

atomsMolecular

formula

Relative atomic mass

for OxygenRelative atomic mass

for Hydrogen

All Ar, Mr and Fr

have no unit




inc nitrate n O3 2

Aluminium nitrate Al O3 3

Calcium carbonate CaCO3

Calcium hydroxide Ca OH 2

Hydrated copper IIsulphate

CuSO4.5H2O 64 + 32 + 4 16 + 5[2 1 + 16]=250

Hydrated sodiumcarbonate

a2CO3.10H2O

Sodium hydrogensulphate

aHSO4

Aluminium chloride AlCl3

Copper II sulphate CuSO4

inc carbonate nCO3

Potassiumcarbonate

K2CO3

[Relative atomic mass: O,16; C,12; H,1; K,39 ; Cu, 64 ; n, 65; Cl, 35.5 ; Al, 27 S,32 ;Ca, 40; a,23; , 14]




B THE MOLE AND THE NUMBER OF PARTICLES

1. Relationship between number of moles and number of particlesatom/ion/molecules :

x Avogadro Constant

A vogadro Constant

umber of moles umber of particles

0.5 mol of carbon atoms «««««««««««««« atoms of carbon

0.2 moles of hydrogen gas H 2 i ««««««««««..moleculesof hydrogen gas

ii «««««««««««.Atoms of hydrogen

2 mol of carbon dioxide molecules ««««««x 1023

molecules of carbon dioxidegas contains :

««««««. atoms of C and

«««««««. atoms of O

0.007 mol of calcium ions ««««««««« calcium ions

««««««««««. mol of water 6.02 x 1025

molecules of water

0.4 mol of o one gas O 3 «««««««.x 10 23 molecules of o one,

contains :

««««««««« atoms of O

a 3 mol of carbon dioxide, CO 2 contains ««««««««««««««.. molecules

b 0.5 mol Copper II nitrate, Cu O 3 2 contains «««««««««««««.. Cu2+

ions and «««««««««««««««««««. O 3- ions

C NUMBER OF MOLES AND MASS OF SUBSTANCESx Molar mass

number of moles number of particles

Number

Of

moles

Mass

in g




Molar mass

1. Calculate the masses of these substancesa 2 moles of aluminium atomsMass =

b 10 moles of iodine atomsMass =

c 3 moles of lithium atomsMass =

d 0.5 moles of oxygen gas O 2 Mass =

e 0.1 moles of sodiumMass =

f 2 moles of chlorine molecules Cl 2 Mass =

2. Calculate the umber of Moles from a given Mass

a 88g of carbon dioxide CO 2 umber of moles = b 3.1g of sulphur dioxide SO 2 umber of moles =

c 560g of potassium hydroxide KOHumber of moles =

d 392g of sulphuric acid H 2SO4 umber of moles =

e 170g of ammonia H 3 umber of moles = f 120g of magnesium oxide MgOumber of moles =

D NUMBER OF MOLES AND VOLUME OF GAS




x 22.4/24 dm 3

22.4/24 dm3

a 3 moles of oxygenVolume =

b 2 moles of CH4 Volume =

c 0.3 moles of ArgonVolume =

d 0.2 moles of SO3 Volume =

e 0.1 moles of 2 Volume =

f 1.5 mol of 2 Volume =

Complete the diagram below . Refer to Page 33,34 & 38-Chemistry textbook

Solve these numerical pro lems

Number of moles of gas Volume of gas

Volume of gas (dm

3

)

Number of molesMass in gram No of particles




1. What is the volume of 0.3 mole of sulphur dioxide gas at STP?[Molar volume: 22.4 dm 3 mol-1 at STP]

Ans: 6.72 dm3

2. Find the number of moles of oxygen gas contained in a sample of 120 cm 3 of the gasat room conditions.[Molar volume: 24 dm

3mol

-1at room conditions]

ans: 0.005 mol

3. Calculate the number of water molecules in 90 g of water, H 2O.[Relative atomic mass: H, 1; O, 16. Avogadro constant, N A: 6.02 x 10

23mol

-1]

Ans; 3.01x 1024

molecules

4. What is the volume of 24 g methane , CH4 at STP?[Relative atomic mass: H, 1; C, 12. Molar volume: 22.4 dm

3mol

-1at STP]

Ans: 33.6 dm3

5. How many aluminium ions are there in 20.4 g of aluminium oxide, Al 2O3?[Relative atomic mass: O, 16; Al, 27. Avogadro constant, N A: 6.02 x 10

23mol

-




2 x 0.2 x 6.02 x10

23

6. Calculate the number of hydrogen molecules contained in 6 dm3

of hydrogen gas atroom conditions.[Molar volume: 24 dm

3mol

-1at room conditions Avogadro constant, N A: 6.02 x 10

23

mol-1

]

Ans: 1.505x1023

molecules

7. Find the volume of nitrogen in cm3

at STP that consists of 2.408 x 1023

nitrogenmolecules.[Molar volume: 22.4 dm 3 mol-1 at STP. Avogadro constant, N A: 6.02 x 1023 mol-1]

Ans: 8.96 dm3

E CHEMICAL FORMULAE




1 There are two types of chemical formulae. Complete the following:

** Empirical Formula

**M

olecular Formula

2 Find the empirical formula of a compoundExample of calculation:

a When 11.95 g of metal X oxide is reduced by hydrogen, 10. 5 g of metal X isproduced. Find the empirical formula of metal X oxide [ RAM; X,207; O,16 ]

Element X O

Mass of element g 10.35 11.95-10.35

umber of moles of atoms 10.35÷207 11.95-10.35 ÷16

Ratio of moles

Simplest ratio of moles

Empirical formula : «««««

b A certain compound contains the following composition:a 15.23%, Br 52.98% , O 31.79%, [ RAM : O, 16; a, 23; Br,80]

Assume that 100g of substance is used

Element a Br O

Mass of element g 15.23 52.98 31.79

umber of moles atoms 15.23 ÷23 52.98÷80 31.79÷16

Ratio of molesSimplest ratio of moles

Empirical formula:: ««««««««««««««««««.

c 2.52g of a hydrocarbon contains 2.16 g of carbon. The relative molecular mass of thehydrocarbon is 84. [RAM H,1; C,12]i. Find the empirical formula of the hydrocarbon

ii. Find the molecular formula of the carbon.

Chemical Formula for ionic compounds:Complete the table below :

Cation Formula Anion Formula




Hydrogen ion

H Flouride ion

F

Lithium ion Chloride ion

Sodium ion Bromide ion

Potassium ion Iodide ion

Magnesium ion Hydroxide ionCalcium ion 2

Ca itrate ion

Barium ion 2 Ba Manganate VII ion

Copper II ion Ethanoate ion

C OOC H 3

Iron II ion 2O

Iron III ion Sulphate ion

Lead II ion Sulphide ion 2S

inc ion Carbonate ion

Chromium III ion Dichromate VI ion 2

72

OCr

Aluminium ion 3 Al 3

4 P O

Ammonium ion Chromate VI ion

a Chemical formula of an ionic compound comprising of the ions Xm+

and Yn-

is constructedby exchanging the charges of each element. The formula obtained will X nYm

Example : Sodium oxide Copper II nitrate

a+

O2-

Cu2+

O3-

+1 -2 +2 -1

2 1 1 2

= a2O = ....................

b Construct a chemical formula for each of the following ionic compounds:i Magnesium chloride ii Potassium carbonate

iii Calcium sulphate iv Copper II oxide

v Silver nitrate vi inc nitrate




vii Aluminium oxide viii Iron II hydroxide

ix Lead II sulphide

CHEMICAL E UATIONS

x Chromium III sulphate

Complete the following word equations and write in chemical equation

a Sodium + chlorine ««««««««««..

«««« + ««««« aCl

b Carbon + «««.. Carbon dioxide

«««. + «««« ««««««««..

c Sulphur + oxygen «««««««««««

«««.. + «««.. ««««««««««..

d inc + oxygen ««««««««««««..

«««« + O2 ««««««««««««..

3 Write a balanced equation for each of the following reactions and interpret the equationsquantitatively.

a . Carbon monoxide gas + oxygen gas carbon dioxide gas

«««««««««««««««««««««««««««««««««««««««

Interpreting:

«««««««««««««««««««««««««««««««««««««««««

b . Hydrogen gas + nitrogen gas ammonia gas

«««««««««««««««««««««««««««««««««««««««.




( Ans : 12.8 g "

4 . A student heats 20 g of calcium carbonate3

CaC O strongly. It decomposes according to

the equation below:

3CaC O (s CaO (s +

2C O (g .

(a . If the carbon dioxide produced is collected at room conditions, what is its volume?

(b . Calculate the mass of calcium oxide, CaO produced.

[Relative atomic mass: C, 12 ; O, 16; Ca, 40. Molar volume :

24 dm3 1mol at room conditions]

( Ans : (a# . 4.8 dm3 (b # 11.2 g #

modul kimia f4

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