In this Science (Chemistry) video in Hindi for class 9 we explained valency and how it depends upon the electronic configuration. This is a topic from Chapter 4 -'Structure of Atom' of NCERT Science.
Most of the elements are chemically active, i.e., they participate in chemical reactions and produce compounds. But some of them are chemically inactive, like, helium, neon, argon, krypton, xenon, radon. These elements are known as inert gases or noble gases. The atoms of these elements have unique feature; they have 8 electrons in their outermost orbit (except for helium, which has 2 electrons in its outermost orbit). Atoms of other elements have tendency to attain the electronic configuration of their nearest noble gas. To attain this they lose or gain electrons or share electrons, which decides their valency. Following are the formulae for valency
For atoms donating electrons : 𝑉𝑎𝑙𝑒𝑛𝑐𝑦 = 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑣𝑎𝑙𝑒𝑛𝑐𝑒 𝑒𝑙𝑒𝑐𝑡𝑟𝑜𝑛𝑠
For atoms accepting / sharing electrons : 𝑉𝑎𝑙𝑒𝑛𝑐𝑦 = 8 − 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑣𝑎𝑙𝑒𝑛𝑐𝑒 𝑒𝑙𝑒𝑐𝑡𝑟𝑜𝑛𝑠
Valency of some elements
name of the element & valency
hydrogen 1
helium 0
lithium 1
beryllium 2
boron 3
carbon 4
nitrogen 3
oxygen 2
fluorine 1
neon 0
sodium 1
potassium 2
aluminium 3
silicon 4
phosphorus 3, 5
sulfur 2, 6
chlorine 1
argon 0
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🔴 Click here to watch the whole playlist on Chapter 4 : 'Structure of Atom' for Class 9 :
• Structure of Atom (Int...
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Previous videos -
🔴 Structure of Atom (Introduction)
• Structure of Atom (Int...
🔴 Discovery of Electron
• Discovery of Electron ...
🔴 Thomson's Atomic Model
• Thomson's Atomic Model...
🔴 Rutherford Atomic Model
• Rutherford Atomic Mode...
🔴 Bohr's Atomic Model
• Bohr's Model of Atom |...
🔴 Discovery of Neutron
• Discovery of Neutron |...
🔴 How are Electrons Distributed in Different Orbits
• Electronic Configurati...
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