revision on chapter periodic table, chemical bonding and electrolysis with answers

PERIODIC TABLEa. i.Label group

1

17

Transition metal

13 14 15 16

182

ii.Label period 1 to 5

Period 1

Period 2

Period 3

Period 4

Period 5

1

2

Transition metal

13 14 15 16 17

18

iii.Place proton number of elements 1 to 20 in the periodic table above

1 2

3 4 5 6 7 8 9 10

11

12 13 14 15 16 17 18

19 20

iv.Place all the elements given in the periodic table above with their

symbols

Transition metal

H He

F Ne

Na

Cu

Cl

Br

Ar

K Mn

Li

b)Why are all noble gases chemically not reactive?

• Because they have stable electron arrangement with octet or duplet structure.

• So they do not release, Gain or share electron

c.State 3 physical properties of element sodium

1.Soft metals (easily cut with a razor blade)

2.Low melting and boiling point compare to other metals

3.Low density

4.Good conductor of heat and electricity

Sodium undergoes the following reactions. Write chemical equation:

i) With oxygen:

ii) With water:

iii) With chlorine:

4Na + O2 2Na2O

2Na + 2H2O 2NaOH + H2

2Na + Cl2 2NaCl

The reaction of Potassium with water is more vigorous than the reaction of sodium with water. Explain

• Because potassium atom is bigger than sodium atom ,

• So the distance between nucleus and valence electron in potassium atom is further than sodium atom

• nuclei attraction in potassium is weaker, therefore easier to release electron

• Potassium is more reactive than sodium

State 3 physical properties of element Chlorine:

• Yellow gas at room temperature

• Turn moist blue litmus paper to red and decolourised

• Very soluble in water

g. Chlorine undergoes reaction with heated iron wool.

Write chemical equation

2Fe + 3Cl2 2FeCl3

or

Fe + Cl2 FeCl2

The reaction of chlorine with heated iron is more vigorous than the reaction of bromine with heated iron . Explain• Chlorine atom is smaller than bromine

atom • The distance between nucleus and

valence electron in Chlorine atom is shorter than bromine atom

• Causing the nuclei attraction to be stronger in chlorine atom

• Thus, chlorine atom is easier to attract electron causing it to be more reactive

State 3 special properties of transition elements compared to other elements

• Form coloured ion and compound

• Have many oxidation number• Act as catalyst• Form complex ion

When going across a period from left to right, the atoms get smaller in size. Explain• as the proton number increase, the

positively charged also increase• Thus, the nuclei attraction also

increase• The electron are pulled closer to the

nucleus causing the size to be smaller

“Sesiapa yang hendak mengetahui

kedudukannya di sisi Allah

maka lihatlah kedudukan Allah di dalam hatinya.

Sesungguhnya Allah SWT meletakkan kedudukan

hambanya di sisiNya sebagaimana hamba meletakkanNya

di dalam dirinya.”THE END TOPIC 4

CHEMICAL BONDS

REVISION

a) Sodium and oxygen ( given proton no. Na, 11: O, 8)

Step 1) determine whether ionic or covalent?

Step 3) Arrange the atoms

Step 4) Draw electron arrangement

Step 2) write formula- so you know how many atoms involve

ionic

Na2O

Na O Na

See next slide

Draw electron arrangement for compounds formed betweena) Sodium and oxygen ( given proton no. Na, 11: O, 8)

a) water ( given proton no. H, 1: O, 8)

Step 1) determine whether ionic or covalent?

Step 3) Arrange the atoms

Step 4) Draw electron arrangement

Step 2) write formula- so you know how many atoms involve

covalent

H2O

H O H

See next slide

b) For water molecule

a) Carbon and chlorine ( given proton no. C, 6: Cl, 17)

Step 1) determine whether ionic or covalent?

Step 3) Arrange the atoms

Step 4) Draw electron arrangement

Step 2) write formula- so you know how many atoms involve

covalent

CCl4

See next slide

c) Carbon and chlorine

State 3 physical properties of sodium oxide

• Solid at room temperature• Soluble in water• Insoluble in organic solvent• Conduct electricity in molten

and aqueous state• High melting point and boiling

point

State 3 physical properties of water

• Does not conduct electricity in in any state

• Low melting point and boiling point

• Colourless liquid at room temperature

1. MOLTEN LEAD(II)IODIDE WITH CARBON ELECTRODE

1)Electrolysis of molten PbI2 using carbon as electrode

a)Ions present :

Anode(+) Cathode(-)b)Ion attracted c) Ion discharged

Pb2+ , I-

I- Pb2+

I- Pb2+

d) Half equation :ANODE : CATHODE :

e) Product :

• ANODE :

• CATHODE :

2I- I2+2ePb2+ +2e Pb

Iodine gas

Lead metal

ANODE CATHODE

OBSER A PURPLE GAS EVOLVED

GREY AND SHINY SOLID DEPOSITED

2. HYDROCHLORIC ACID 0.0001 moldm-3 WITH CARBON ELECTRODE

ALL IONS PRESENT

H+ , Cl- & OH-

2)Electrolysis of HCl, 0.0001 moldm-3 using carbon as electrode

a)Ion present :

Anode Cathodeb)Ion attracted c) Ion discharged

H+ , Cl- , OH-

Cl- , OH- H+

OH-H+

d) Half equation :ANODE : CATHODE :

e) Product :

• ANODE :

• CATHODE :

4OH- O2+ 2H2O +4e

2H+ +2e H2

Oxygen and water

Hydrogen gas

ANODE CATHODEOBS COLOURLESS

GAS THAT REKINDLES GLOWING WOODEN SPLINTER

COLOURLESS GAS THAT GIVES ‘POP’ SOUND -TESTED USING BURNING WOODEN SPLINTER

2)Electrolysis of CuSO4, 1.0 moldm-3 using carbon as electrode

a)Ions present :

Anode Cathodeb)Ion attracted c) Ion discharged

Cu2+ , SO42- ,H+, OH-

SO42- , OH- Cu2+ , H+

OH- Cu2+

d) Half equation :ANODE : CATHODE :

e) Product :

• ANODE :

• CATHODE :

4OH- O2+ 2H2O +4e

Cu2+ +2e Cu

Oxygen and water

Copper metal

2)Electrolysis of CuSO4, 1.0 moldm-3 using copper as electrode

a)Ions present:

Anode Cathodeb)Ion attracted c) Ion discharged

Cu2+ , SO42- ,H+, OH-

SO42- , OH- Cu2+ , H+

Cu2+No ions are discharged

d) Half equation :ANODE : CATHODE :

e) Product :

• ANODE :

• CATHODE :

Cu Cu2+ +2e

Cu2+ +2e Cu

Copper(II) ions

Copper metal