3. Elements are arranged systematically in the Periodic
Table in the order of increasing proton number
which enables:
• Chemists to study understand and remember the
chemical and physical properties of all elements
and compounds in an orderly manner.
• Properties of elements and their compounds are
predicted based on the position of elements in
the Periodic Table.
• Relationship between the elements from
different group can be known.
5. 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
6. 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
7. 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.
9. • Helium (He), Neon (Ne), Argon (Ar), Krypton
(Kr), Xenon (Xe) and Radon (Rn).
• The elements are known as noble gases.
• Noble gases are monoatomic.
10. 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
11. Inert property of Group 18
• All noble gases are inert (chemically
unreactive)
• 2 valence electron – duplet electron
arrangement
• 8 valence electron – octet electron
arrangement
12. 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.
13. 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.
14. 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
15. 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
16. Krypton
• Used in lasers to repair the retina of the
eye
• Used to fill photographic flash lamps
Radon
• Used in the treatment of cancer
17. Xenon
• Used for making electron tubes and
stroboscopic lamps
• Used in bubble chambers in atomic energy
reactors
20. • Lithium (Li), Sodium (Na), Potassium (K),
Rubidium (Rb), Caesium (Cs), Francium (Fr)
• The elements are known as alkali metals.
• All Group 1 elements have 1 valence electron,
so they are NOT STABLE
21. Physical properties:
1. Grey solid
2. Shiny surface
3. Softer than other metals
4. Low melting point
5. Low boiling point
6. Low density
7. Good conductor of heat & electricity
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22. Going down Group 1
Size of atom increase
• There are more shells that occupied with
electrons
Density increases
• Mass increases much faster than volume
23. Melting & boiling points decrease
• Atomic size increases
• Metallic bond between atoms of alkali metals
becomes weaker
• less heat energy is needed to overcome the
forces of attraction
24. Reactivity increase
• Atomic size increases
• Valence electron is further away from nucleus
• Nucleus force of attraction becomes weaker
• Electron can be donated/released more easily
• More reactive
29. • All G1 elements have 1 valance electron, so
they are NOT STABLE
• G1 elements will donate/release 1 valance
electron to be stable
• It is easier to donate/release 1 valence
electron, the higher reactivity
40. • Fluorine (F), Chlorine (Cl), Bromine (Br),
Iodine (I), Astatine (At)
• The elements are known as halogens.
• Exist as diatomic molecules.
• They are poisonous.
41. 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
43. Chemical properties:
1. Reaction with water to form acids
X2 + H2O → HX + HOX
Example:
• Cl2 + H2O → HCl + HOCl
HX & HOX solution – acidic
HOX solution –
bleaching
properties
Hydrochloric
acid
Hypochlorus
acid
44. 2. Halogen + metal metal halide
Example reaction of iron with bromine to form
iron(III) bromide (brown solid)
2Fe + 3X2 → 2FeX3
Example:
• 2Fe + 3Br2 → 2FeBr3
45. 3. Halogen + alkaline solution metal halide +
metal halite + water
Example: Reaction halogen 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)
46.
47.
48. 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.
49. 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
50. Safety precautions
• Handle the elements in a fume chamber
• Wear safety goggles and gloves when handling
halogens
51.
52. Elements
• Sodium, Na
• Magnesium, Mg
• Aluminium,Al
• Silicon, Si
• Phosphorus,P
• Sulphur, S
• Chlorine, Cl
• Argon, Ar
53.
54. Across the period
• The proton number increase by one unit from
one element to next element
• All the atoms have three shells occupied with
electrons
• The number of valence electron in each atom
increase from 1 to 8
55.
56. Changes in Physical Properties of
Elements Across Period 3
• Size of atom decrease – because the atomic
radius decrease
• Electronegativity increase:
• Increase the number of proton will increase
the charge in the atom’s nucleus
• Force attraction between nucleus and valence
electron stronger
• It is easier for nucleus to attract electron into
the atom
57. Acid-base properties of oxides of
elements on Period 3
• Metal oxide:
Metal oxide that show basic properties
• Amphotheric oxide:
Some oxides that show basic and acidic
properties
• Non-metal oxide:
usually show acidic properties
58. Across period 3;
• The oxides of elements change from basic
acidic properties:
Na, Mg
• Amphoteric oxide:
Al
• Acidic non-metal oxide:
Si, P, S, Cl
59. 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.)
62. 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
63. Special characteristics of
transition elements
• Shows different oxidation numbers in
their compounds
• Form coloured ions or compounds
• Useful as catalyst
64. Use in industries
Haber process:
• Manufactured of ammonia, NH3
• Catalyst: Iron, Fe
Ostwald process:
• Manufactured of nitric acid, HNO3
• Catalyst: Platinum, Pt
65. Contact process:
• Manufactured of sulphuric acid, H2SO4
• Catalyst: Vanadium(V) oxide, V2O5
Manufacture of margarine
• Catalyst: Nickel, Ni
