PERIODIC TABLE OF ELEMENTS

MODERN PERIODIC TABLE OF ELEMENTS

INFO FROM PERIODIC TABLE OF ELEMENTS :
1 GROUP - 18
2 PERIOD - 7
3 TRANSITION ELEMENTS
4 LANTHNIDE SERIES
5 ACTINIDE SERIES
6 METAL
7 SEMI-METAL
8 NON-METAL

PERIODIC TABLE OF ELEMENTS

HISTORICAL DEVELOPMENT OF THE PERIODIC TABLE

Antoine Lavoisier
First scientist to classify substances into groups
Unsuccessful because light, heat and few
compounds were considered as element

Johann dobereiner

 Classified elements into group of three
elements with similar chemical properties,

known as triad

John Newlands
 Arranged the elements in order of increasing

atomic mass.
 Elements with similar properties recurred at

every eigth element, known as the Law of
Octave



Lothar Meyer (German)

 Plotted a graph of the atomic volume
against the atomic mass for all known
elements

 Elements with similar chemical properties
occupied equivalent position

Na K Rb

F Cl Br

Dmitri Mendeleev(Russian)
 Left gaps in the table to be filled by

undiscovered elements

Henry J.G Moseley (American)
 Arranged the elements in order of

increasing proton number (basic
arrangement of elements in modern
Periodic Table)



How do the elements arrange in the Periodic Table ?
Based on increasing proton number

How do the elements arrange in the group ?
Based on the valence electrons

How do the elements arrange in periodic ?
Based on number of shells occupied by electrons

Electron arrangement
2.1

2.8.1
2.8.8.1

Electron arrangement
2.2

2.8.2

2.8.8.2

Electron Electron
arrangement arrangement
2.3 2.4

2.8.3 2.8.4



Example 1 :
Element Q has 12 protons. Determine the group and
period of element Q.

Example 2 :
Elements Y has nucleon number 27 and 14 number
of neutrons. Determine the group of Y

Example 3 :
Determine the location Of element R in the Periodic
Table, if R has proton number 17.









PHYSICAL PROPERTIES OF GROUP 18 ELEMENTS



Why the melting P & Boiling P of the elements of Group
18 increases when moving down the group ?
Explain why.
1. Proton number increases (no of electrons also

increases
2. no of electron filled shells increases

3. atomic radius (size) increases

4. attractive forces between particles(atoms) becomes
stronger

5. more heat is needed to overcome the attractive forces
between particles

6. melting P & Boiling P increases

Why there are chemically
unreactive/inert

1. They have achieved the duplet or octet
electon arrangement

2. They do not donate, receive or share
electrons with other atom

Achieved the duplet or octet electon
arrangement

Uses of noble gases











USES OF INERT GASES (GROUP 18 ELEMENTS)

•The gas is much less dense than
air. Therefore it is used in balloons
and 'airships'.
•Because of its inertness it doesn't
burn in air UNLIKE hydrogen which
used to be used in large balloons
with 'flammable' consequences.

1.Helium is also used in gas
mixtures for deep-sea divers.
2.This is because the solubility of
the helium is very low. Therefore it
will not dissolve in the blood even
though the pressure of the
surrounding is very high.
•.

•Neon emits light when high voltage

electricity is passed through it.
•Because of this, it is used in glowing
'neon' advertising signs and fluorescent

lights.

USES OF INERT GASES (GROUP 18 ELEMENTS)

•Argon, like all the Noble •Argon also used to produce an
Gases is chemically inert. inert atmosphere in high
•It used in filament bulbs temperature metallurgical
because the metal filament processes, eg in welding where
will not burn in Argon and it it reduces brittle oxide formation
reduces evaporation of the reducing the weld quality.
metal filament.

4 Krypton and xenon

•Krypton is used in fluorescent bulbs,
flash bulbs and laser beams

bulb camera flash(xenon)

bulb

Radon

Radiotherapy - Treat cancer patient



Comparison of Group 18 and 1

Why the melting P & Boiling P Why the melting P & Boiling P of
of the elements of Group 18 the elements of Group 1
increases when moving down decreases when moving down
the group ? the group ?
1. no of electron filled shells
1. no of electron filled
increases shells increases
2. atomic radius (size)
2. atomic radius (size)
increases increases
3. attractive forces between
3. attractive forces between
particles(atoms) becomes particles becomes weaker
stronger
4. more heat is needed to 4. less heat is needed to
overcome the attractive overcome the attractive
forces between particles forces between particles
5. melting P & Boiling P
increases 5. melting P &
Boiling P decreases

Chemical Reaction of Group 1

Reaction with water

Bil Element Observation Inference

1 Lithium 1. moves slowly on 1. Less reactive than

the surface of sodium

water with ‘hiss’ 2. The solution formed

sound is litium hydroxide

2. A colourless

solution produced

turn pink when

added with a few

drops of

phenolphthalein

(turn red litmus

paper blue)

Bil Element Observation Inference

1 sodium 1. moves quickly on 1. more reactive than

the surface of lithium

water with ‘hiss’ 2. The solution formed

sound is sodium hydroxide

2. A colourless

solution produced

turn pink when

added with a few

drops of

phenolphthalein

(turn red litmus

paper blue)

Bil Element Observation Inference

1 potassium 1. moves vigorously 1. more reactive than

on the surface of lithium

water with lilac 2. The solution formed

flame and a small is potassium

explosion hydroxide

2. A colourless

solution produced

turn pink when

added with a few

drops of

phenolphthalein

(turn red litmus

paper blue)

Chemical Reaction of Group 1

Reaction with oxygen

Bil Element Observation Inference

1 Litium 1. Burnt slowly with a 1. Less reactive than

red flame sodium

2. White fume 2. White solid is litium

produced turn to oxide

white solid when 3. Litium hydroxide

cooled formed when white

3. White solid solid dissolved in

dissolved in water water

and turn pink

when added with a

few drops of

phenolphthalein

Bil Element Observation Inference

2 Sodium 1. Burnt fast with a 1. More reactive

yellow flame than litium

2. White fume 2. White solid is

produced turn to sodium oxide

white solid when 3. Sodium hydroxide

cooled formed when

3. White solid white solid

dissolved in water dissolved in water

and turn pink

when added with

a few drops of

phenolphthalein

Bil Element Observation Inference

3 Potassium 1. Burnt vigorously 1. More reactive than

with a sodium

lilac(purplish) 2. White solid is

flame potassium oxide

2. White fume 3. potassium

produced turn to hydroxide formed

white solid when when white solid

cooled dissolved in water

3. White solid

dissolved in water

and turn pink

when added with

a few drops of

phenolphthalein





1. GROUP 1 WITH WATER

2Li + 2H2O 2 LiOH + H2

2Na + 2H2O 2 NaOH + H2
2K + 2H2O 2 KOH + H2

2 GROUP 1 WITH OXYGEN

4Li + O2 2 Li2O

4Na + O2 2 Na2O

4K + O2 2 K2O

3. GROUP 1 WITH CHLORINE

2Li + Cl2 2 LiCl

2Na + Cl2 2 NaCl
2K + Cl2 2 KCl

GROUP 17 (HALOGEN)

 PYHSICAL PROPERTIES
 CHEMICAL PROPERTIES :
1. CHEMICAL EQUATION
2. OBSERVATION
3. REACTIVITY- EXPLANATION
4. (CONTENT IN THE VIDEO)