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Question
What is the significance of atomic number in the modern classification of elements? Explain with the help of an example.
Solution
The significance of atomic numbers in the modern periodic table is that it helps in arranging the elements according to their electronic configuration. Since, the number of valence electrons is the same, elements placed in the same group show similar chemical properties.
For example, if we take the element lithium (Li), its atomic number is 3. Its electronic configuration is (2,1). As it has one valence electron, it is placed in the first group of the periodic table. Similarly, all the elements having one valence electron will be placed in group 1, and they show similar chemical properties. In this manner, classification of elements is made according to the electronic configuration of the elements.
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RELATED QUESTIONS
Compare and contrast the arrangement of elements in Mendeleev’s periodic Table and the Modern Periodic Table.
The following diagram shows a part of the periodic table in which the elements are arranged according to their atomic numbers. (The letters given here not the chemical symbols of the elements):
| a 3 |
b 4 |
c 5 |
d 6 |
e 7 |
f 8 |
g 9 |
h 10 |
|
| i 11 |
j 12 |
k 13 |
l 14 |
m 15 |
n 16 |
o 17 |
p 18 |
(i) Which element has a bigger atom, a or f?
(ii) Which element has a higher valency, k or o?
(iii) Which element is more metallic i or k?
(iv) Which element is more non-metallic, d or g?
(v) Select a latter which represents a metal of valency 2.
(vi) Select a letter which represents a non-metal of valency 2.
What is meant in the periodic table by a period?
What is the number of elements in the 1st period?
Mendeleev's periodic table : atomic mass : : Modern periodic table : _______
Group 1 and 2 : s block : : group 13 and 18 : _______
Which of the following statements about the Modern Periodic Table is correct:
Spot the error:
The elements of group 13 are called the carbon family.
Spot the error:
There are 5 periods and 17 groups in the modern periodic table.
Define groups of modern periodic table.
