Chapter 1:Chemical Reaction And Equations
Chapter 2:Acids, Bases and Salts
Chapter 3:Metals and Non-metals
Chapter 4:Carbon and Its Compounds
Chapter 5: Periodic Classification of Elements
Chapter 10: Light Reflection and Refraction
Chapter 11:Human Eye and Colourful World
Döbereiner’s Triads
Newlands’ Law of Octaves
When the elements are arranged according to
increasing atomic masses, the properties of every eighth element are similar to that of the first
element
Newlands compared this to the octaves found in music( sa, re, ga, ma, pa,
da, ni) , he called it the ‘Law of Octaves’.
Limitation:
MENDELÉEV’S PERIODIC TABLE<:< /b>
Achievements of Mendeléev’s Periodic Table:
Limitations of Mendeléev’s Classification:
THE MODERN PERIODIC TABLE:
Modern
Periodic Law :‘Properties of elements are a periodic function of their atomic
number.’
The Modern Periodic Table has 18 vertical columns known as ‘groups’
and 7 horizontal rows known as ‘periods’.
Periods in Modern Periodic Table:
Characteristics of Periods:
Groups in Modern Periodic Table:
Characteristics of group:
Valency : the number of valence electrons present in the outermost shell of its atom.On moving left to right in period the number of velence electron increase while velence in group remain same
Atomic size: the distance between the centre of the nucleus and the
outermost shell of an isolated atom
In period the atomic radius decreases in moving from left to
right along a period. This is due to an increase in nuclear charge which
tends to pull the electrons closer to the nucleus and reduces the size of
the atom
In group, the atomic size increases down the group. This is
because new shells are being added as we go down the group. This
increases the distance between the outermost electrons and the nucleus
so that the atomic size increases in spite of the increase in nuclear charge.
Metallic: metals tend to lose electrons while
forming bonds, they are electropositive in nature
Down the group, the effective nuclear charge
experienced by valence electrons is decreasing because the outermost electrons are farther away
from the nucleus. so they lost electron easily. metallic
character decreases across a period and increases down a group
Non-metals:Non-metals are electronegative. They tend to form
bonds by gaining electrons. so non-metals are found on
the right-hand side of the Periodic Table towards the top.
These trends also help us to predict
the nature of oxides formed by
the elements because it is known to you that the oxides of metals are
basic and that of non-metals are acidic in general.
Chapter 1:Chemical Reaction And Equations
Chapter 2:Acids, Bases and Salts
Chapter 3:Metals and Non-metals
Chapter 4:Carbon and Its Compounds
Chapter 5: Periodic Classification of Elements
Chapter 10: Light Reflection and Refraction
Chapter 11:Human Eye and Colourful World