The document summarizes key aspects of the periodic table including: 1) Elements are arranged in order of increasing proton number and elements with similar properties are in the same group, with groups 1-18 and periods 1-7. 2) Group 18 elements are noble gases with full outer shells making them chemically inert monoatomic gases. 3) Group 1 elements are alkali metals that react vigorously with water and oxygen and reactivity increases down the group as atomic size increases. 4) Group 17 elements are halogens that exist as diatomic molecules and reactivity decreases down the group as atomic size increases. 5) Period 3 elements include metals, nonmetals and semi-metals that show trends

1. CHAPTER 4
Periodic Table
of Elements

2. A. The Periodic Table of Elements

3. Historical Development of the
Periodic Table

4. Arrangement of elements in the
Periodic Table
• Arranged in an increasing order of proton
number (from 1 → 113)
• Elements with similar chemical properties are
placed in the same vertical column

5. Each vertical column of elements is called a group.
The vertical columns are known as Group 1 to Group 18.
The number of valance electrons in an atom decides the
position of the group of an element in the Periodic Table.
For elements with 1 to 2 valence electrons,
The group of an element
= The number of valence electrons in its atom
For elements with 3 to 8 valence electrons,
The group of an element
= The number of valence electrons in its atom + 10

6. Each of these horizontal rows of elements is called period.
The horizontal rows are known as Period 1 to Period 7.
The number of shells occupied with electrons in the
atom decides the position of the period of an element
in the Periodic Table.

7. B. Group 18 Elements

8. • Helium (He), Neon (Ne), Argon (Ar), Krypton
(Kr), Xenon (Xe) and Radon (Ra).
• The elements are known as noble gases.
• Noble gases are monoatomic.

9. Physical properties
1. Low melting point/boiling point
2. Low density
3. Colourless gases
4. Very small atomic size
5. Insoluble in water
6. Cannot conduct electricity
7. Poor conductor of heat

10. Inert property of Group 18
• All noble gases are inert (chemically
unreactive)
• 2 valence electron – duplet electron
arrangement
• 8 valence electron – octet electron
arrangement

11. Why noble gases exist as monoatomic gases
and chemically unreactive?
Ans:
• Because the outermost shell occupied with
electron are full / achieve the duplet or octet
electron arrangement.
• So, noble gas does not donate, receive or
share electron with other elements.

12. Going down Group 18
Size of atom increase
• Going down Group 18 elements, the numbers
of shells occupied with electron in the atom
increase.
• The size of atom increase.

13. Melting & boiling points increase
• Going down the group, size of atom increase /
become bigger
• The forces of attraction between the atoms
become stronger
• Thus, more heat energy is needed to
overcome the stronger forces of attraction

14. Use of Group 18 elements
Helium
• Used to filled airships and weather balloons
Neon
• Used in advertising light and television tubes
Argon
• Fill light bulbs
• Used to provide inert atmosphere for welding
at high temperature

15. Krypton
• Used in lasers to repair the retina of the
eye
• Used to fill photographic flash lamps
Radon
• Used in the treatment of cancer

16. Xenon
• Used for making electron tubes and
stroboscopic lamps
• Used in bubble chambers in atomic energy
reactors

17. C. Group 1 Elements

18. • Lithium (Li), Sodium (Na), Potassium (K),
Rubidium (Rb), Caesium (Cs), Francium (Fr)
• The elements are known as alkali metals.

19. Physical properties:
1. Low melting point/boiling point
2. Low density
3. Surfaces
4. Silvery and shiny surface
5. Good conductor of heat & electricity

20. Chemical properties:
With water
2M + 2H2O → 2MOH + H2
Example:
• 2Li + 2H2O → 2LiOH + H2
• 2Na + 2H2O → 2NaOH + H2

21. With oxygen gas
4M + O2 → 2M2O
Example:
• 4Na + O2 → 2Na2O
• 4K + O2 → 2K2O

22. Metal oxide with water
M2O + H2O → 2MOH
Example:
• Li2O + H2O → 2LiOH
• Na2O + H2O → 2NaOH

23. With chlorine/bromine gas
2M + Cl2 → 2MCl
2M + Br2 → 2MBr
Example:
• 2K + Br2 → 2KBr
• 2Na + Cl2 → 2NaBr

24. Going down Group 1
Size of atom increase
• Going down Group 1 elements, the numbers
of shells occupied with electron in the atom
increase.
• The size of atom increase.

25. Melting & boiling points decrease
• Going down the group, size of atom increase /
become bigger
• The forces of attraction between the atoms
become weaker
• Thus, less heat energy is needed to overcome
the weak forces of attraction

26. Reactivity increase
• Going down the group, size of atom increase / become
bigger
• The single valence electron in the outermost occupied
shell become further away from nucleus
• The attraction between the nucleus and valence
electron becomes weaker
• It is easier for the atom to release/donate the single
valence electron to achieve the stable electron
arrangement
• Reactivity increase

27. Safety precautions
• Must stored in paraffin oil in bottles
• Do not hold alkali metals with your bare hands
• Use forceps to take alkali metals
• Wear safety goggles and gloves
• Used only small pieces of alkali metal when
conducting experiments

28. D. Group 17 Elements

29. • Fluorine (F), Chlorine (Cl), Bromine (Br),
Iodine (I), Astatine (At)
• The elements are known as halogens.
• Exist as diatomic molecules.
• They are poisonous.

30. Physical properties:
• Low melting point/boiling point
• Exist as diatomic molecule
• Change in physical state
Fluorine – pale yellow gas
Chlorine – greenish-yellow gas
Bromine – reddish-brown liquid
Iodine - purplish-black solid

31. Chemical properties:
Reaction with water to form 2 acids
X2 + H2O → HX + HOX
Example:
• Cl2 + H2O → HCl + HOCl
HX & HOX solution – acidic
HOX solution –
bleaching
properties
Hydrochloric
acid
Hypochlorus
acid

32. Reaction with hot iron to form iron(III) halides
(brown solid)
2Fe + 3X2 → 2FeX3
Example:
• 2Fe + 3Br2 → 2FeBr3

33. Reaction with sodium hydroxide solution,
NaOH to form sodium halide, sodium halate(I)
& water
X2 + 2NaOH → NaX + NaOX + H2O
Example:
• I2 + 2NaOH → NaI + NaOI + H2O
Sodium
iodide
Sodium
Iodate(I)

34. Going down Group 17
Size of atom
• Going down Group 17 elements, the numbers
of shells occupied with electron in the atom
increase.
• The size of atom increase.

35. Melting & boiling points increase
• Going down the group, size of atom increase /
become bigger
• The forces of attraction between the atoms
become stronger
• Thus, more heat energy is needed to
overcome the stronger forces of attraction

36. Reactivity decrease
• Going down the group, size of atom increase /
become bigger
• The attraction between the nucleus and
valence electron becomes weaker
• It is difficult for the atom to receive/attract
one electron to achieve the stable electron
arrangement
• Reactivity decrease

37. Safety precautions
• Handle the elements in a fume chamber
• Wear safety goggles and gloves when handling
halogens

38. E. Elements in Period
(Period 3)

39. Elements
• Sodium, Magnesium, Aluminium, Silicon,
Phosphorus, Sulphur, Clorine, Argon

40. Acid-base properties of oxides of
elements on Period 3
• Metal oxide:
Metal oxide that show basic properties
• Amphoteric oxide:
Metal oxide that show basic and acidic
properties
• Non-metal oxide:
Metal oxide that show acidic properties

41. Elements in:
• Basic metal oxide:
Na, Mg
• Amphoteric oxide:
Al
• Acidic non-metal oxide:
Si, P, S, Cl

42. Across the period
• The proton number increase by one
• All the atoms have three shells occupied with
electrons
• The number of valence electron increase by
one
• All element exist as solid except chlorine and
argon (gases)

43. • Size of atom decrease – force attraction
between nucleus and valence electron
become stronger
• Electronegativity increase:
• Size of atom become smaller
• Force attraction between nucleus and
valence electron stronger
• It is easier for nucleus to attract electron
into the atom

44. Use of semi-metal
• Semi-metal (metalloid) – weak conductors of
electricity
Used as semiconductor
• Used of semiconductor:
Make diodes and transistors (making
microchips for computer, mobile phones,
televisions, video recorders etc.)

45. F. Transition Elements
(Metals)

46. Elements
• Element from Group 3 to Group 12

47. Physical properties
1. Shiny surfaces
2. Ductile
3. Malleable
4. High tensile strength
5. High melting & boiling points
6. High density
7. Good conductor of heat & electricity

48. Special characteristics of
transition elements
• Shows different oxidation numbers in
their compounds
• Form coloured ions or compounds
• Useful as catalyst

49. Use in industries
Haber process:
• Manufactured of ammonia, NH3
• Catalyst: Iron, Fe
Ostwald process:
• Manufactured of nitric acid, HNO3
• Catalyst: Platinum, Pt

50. Contact process:
• Manufactured of sulphuric acid, H2SO4
• Catalyst: Vanadium(V) oxide, V2O5
Manufacture of margarine
• Catalyst: Nickel, Ni