major periodic properties definition and its trend in the periodic table

1. Periodic Properties
Sreenandu
Jr. Faculty for Chemistry

2. Periodic Properties
Properties which repeat at regular intervals  periodic properties
 Atomic radius
 Ionic radius
 Ionization enthalpy
 Electron gain enthalpy
 Electro negativity
 valency

3. Atomic radius
• ‘ it is the distance from the center of the nucleus to the
outermost shell of electrons’

4. Periodic trend of atomic radius

5. Ionic
radius

6. Isoelectronic species

7. Ionization enthalpy
• ‘Minimum amount of energy required to remove the most loosely bound
electron from an isolated gaseous atom’
• Unit – kJ mol-1
Factors affecting IE
Factors affecting
IE
Change Effect on IE Remark
Atomic size Increases decreases Nuclear attraction decreases
Nuclear charge
Positive increases Nuclear attraction increases
negative Low IE Nuclear attraction decreases
Screening or
shielding effect
No. of
inner
electron
increases
IE
decreases
Inner electron shield outer electron
from nuclear attraction
Half or completely
filled orbitals
increases Extra stability
Eg IE of N > O
Type of subshell Order of energy to remove electron
s > p > d > f

8. IE

9. Electron gain enthalpy
‘Amount of energy released when an electron is
added to an atom’
Factors affecting Change Effect on
Electron gain
enthapy
Remark
Atomic size Increases low Nuclear attraction decreases
Nuclear charge
Positive high Nuclear attraction increases
negative low Nuclear attraction decreases
Variation along a period  left to right more negative
( Be, N and noble gases have positive)
Variation ina group  less negative ( but Cl has more than F)

10. Electronegativity
‘It is the tendency to attract shared pair of
electrons towards it’.
Depends onFactors affecting Change Effect on
Electronegativity
Remark
Atomic size Increases low Nuclear attraction decreases
Nuclear charge
Positive high Nuclear attraction increases
negative low Nuclear attraction decreases

12. Periodic trend of chemical properties
• Valency / oxidation state
• Metallic character
• Reducing character
• Oxidizing character

13. Valency
“the combining power of an element, especially as
measured by the number of hydrogen atoms it can
displace or combine with”
Or it is the number of electrons gaining or losing to
make bonds

14. Metallic character
• Tendency to become electropositive
• Decreases from left to right
• Increases from top to bottom
Therefore, 1st group elements will have
more metallic character( Alkali metals)

15. Reducing character
• They provide electrons
• Thus metal act as good reducing agents
• Reducing character decreases across the
period
• It increases down the group
• Alkali metals are very good reducing agents

16. Oxidizing character
• They accept electrons
• Non metals are good oxidizing agents
• Oxidizing character increases across the period
• Decreases down the group
• Halogens are very good oxidizing agents

17. Summary