Page 58 - Chemistry ICSE Class X

46 ICSE Chemistry – 10

ϭϱ͘ ,Žǁ ǁŝůů LJŽƵ ĮŶĚ ŽƵƚ ǁŚŝĐŚ ŽĨ ƚŚĞ ǁĂƚĞƌͲƐŽůƵďůĞ ĐŽŵƉŽƵŶĚƐ ĂŶĚ ŝƐ ĞůĞĐƚƌŽǀĂůĞŶƚ͍ ^ĞůĞĐƚ ŽŶĞ ĞůĞĐƚƌŽǀĂůĞŶƚ ĂŶĚ ŽŶĞ
ĐŽǀĂůĞŶƚ ĐŽŵƉŽƵŶĚ ĨƌŽŵ ƚŚĞ ĨŽůůŽǁŝŶŐ͕
hƌĞĂ͕ ĂŶĞ ƐƵŐĂƌ͕ ,LJĚƌŽŐĞŶ ĐŚůŽƌŝĚĞ ŐĂƐ͕ ĂůĐŝƵŵ ĐŚůŽƌŝĚĞ ĂŶĚ DĂŐŶĞƐŝƵŵ ĐŚůŽƌŝĚĞ͘
ϭϲ͘ EĂŵĞ Ă ŶŝƚƌŽŐĞŶ ĐŽŶƚĂŝŶŝŶŐ ŵŽůĞĐƵůĞ ǁŚŝĐŚ
;ĂͿ ĐŽŶƚĂŝŶƐ Ăůů ĐŽǀĂůĞŶƚ ďŽŶĚƐ͘
;ďͿ ĐŽŶƚĂŝŶƐ ĐŽǀĂůĞŶƚ ďŽŶĚƐ ĂŶĚ Ă ůŽŶĞ ƉĂŝƌ ŽĨ ĞůĞĐƚƌŽŶƐ͘
;ĐͿ ĐŽŶƚĂŝŶƐ ďŽƚŚ ƚŚĞ ĐŽǀĂůĞŶƚ ĂŶĚ ŝŽŶŝĐ ďŽŶĚƐ͘

Polar and Nonpolar Covalent Bonds

Depending upon the nature of the atoms which combine with each other
by mutual sharing of electrons, the following two types of covalent bonds
CTG HQTOGF
ƒ Nonpolar covalent bond
ƒ Polar covalent bond

What is a nonpolar covalent bond

Nonpolar covalent bond is formed between two atoms of the same element.
Atoms of the same element attract electrons equally. So, when a covalent
bond is formed between two atoms of the same element, the electrons are
shared equally between the two atoms. In other words, the shared electron
pair lies exactly midway between the two atoms.
Nonpolar covalent bonds are formed in the molecules, such as H , O ,
2
2
Cl , etc.
2

What is a polar covalent bond

DŽůĞĐƵůĞƐ ŝŶ ǁŚŝĐŚ ƚŚĞ ĂƚŽŵƐ ĂƌĞ The covalent bond between the atoms of two elements having different
ďŽŶĚĞĚ ďLJ Ă ƉŽůĂƌ ĐŽǀĂůĞŶƚ ďŽŶĚ ĂƌĞ electronegativities is called a polar covalent bond.
ĐĂůůĞĚ polar molecules͘ When a covalent bond is formed between two atoms of different
elements, the shared pair of electrons does not lie exactly midway
between the two atoms. In fact, it lies more towards the atom which is
OQTG GNGEVTQPGICVKXG 6JG CVQO YKVJ JKIJGT CHſPKV[ HQT GNGEVTQPU FGXGNQRU
C UNKIJV PGICVKXG EJCTIG CPF VJG CVQO YKVJ NGUUGT CHſPKV[ HQT GNGEVTQPU
develops a slight positive charge.
^ŽŵĞ ƚLJƉŝĐĂů ƉŽůĂƌ ŵŽůĞĐƵůĞƐ ĂƌĞ
ͻഩtĂƚĞƌ , K In the hydrogen chloride (HCl) molecule, hydrogen and chlorine
Ϯ
atoms are bonded through electron sharing.
ͻഩ ŵŵŽŶŝĂ E,
ϯ

ͻഩ,LJĚƌŽŐĞŶ ŇƵŽƌŝĚĞ