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CISCE(English Medium) ICSE Class 10
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MCQ ऑनलाइन सराव परीक्षा७
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संकल्पना स्पष्टीकरण आणि व्हिडिओ३५५
टाइम टेबल१९
अभ्यासक्रम

Chemical Bond

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Topics

  • Introduction
  • Kossel-Lewis Approach to Chemical Bonds
  • Lewis Dot Structure

Introduction:

A bond is a force that holds two or more atoms together in a molecule or compound. Bonds are formed by the interaction of valence electrons to achieve a stable electron configuration. The force of attraction between atoms, known as a chemical bond, enables the formation of chemical compounds. Atoms form chemical bonds to attain a stable electron configuration (like noble gases with a complete octet or duplet).

Types of chemical bonds include:

  1. Ionic bond (transfer of electrons)
  2. Covalent bond (sharing of electrons)
  3. Metallic bond (pooling of electrons among metals)

Kossel–Lewis Approach to Chemical Bonds:

Walther Kossel and Gilbert N. Lewis independently proposed that atoms form bonds to achieve a stable electronic configuration.

  • Their model is based on the octet rule: Atoms tend to have 8 electrons in their outermost shell (or 2 for small atoms like hydrogen and helium).
  • Valence electrons are used in bonding. Atoms interact through their outermost electrons.

Ionic Bond Formation (Kossel): Atoms of metals lose electrons, becoming positively charged ions (cations). Nonmetals gain electrons, becoming negatively charged ions (anions). The opposite charges attract, forming an ionic bond (e.g., NaCl).

Covalent Bond Formation (Lewis): Nonmetals share valence electrons with each other to complete their octets. This forms a covalent bond (e.g., H₂O, CO₂).

Lewis Dot Structure:

The Lewis dot structure is a diagram that represents the valence electrons of an atom using dots placed around the chemical symbol. It helps visualise how atoms form bonds by sharing or transferring electrons.

Steps to Draw a Lewis Dot Structure:

  1. Write the Element Symbol: Use the chemical symbol of the element (e.g., H for hydrogen, O for oxygen).
  2. Determine Valence Electrons: Identify the number of valence electrons (outermost shell electrons) for the atom.
  3. Place Dots Around the Symbol: Place dots to represent each valence electron around the element symbol. Use up to 2 dots per side (top, bottom, left, right) until all electrons are shown.
  4. For molecules: Show shared electrons (bonding pairs) between atoms with dots or lines.

For example,

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Related QuestionsVIEW ALL [138]

Explain

Duplet rule for the formation of hydrogen 

Complete the following table:

a. Dativebond ______
b. CaH2 → Ca+H2 ______
c. ______ Reduction
d. ______ Redox reaction

Elements with stable electronic configurations have eight electrons in their valence shell. They are ______.

Name the following:

The shell closest to the nucleus of an atom 

Spot the error/correct the wrong statement:

In the formation of compounds, the inner shell electrons of an atom involved in bonding.

______ is the only noble gas that does not have eight electrons in its valence shell.

Element X is a metal with a valency 2. Element Y is a non metal with a valency 3.
(a) Write equations to show how X and Y form ions.
(b) If Y is a diatomic gas, write the equation for the direct combination of X and Y to form a compound.

Five atoms are labelled from A to E.

Atoms Mass No. Atomic No.
A 40 20
B 19 9
C 7 3
D 16 8
E 14 7

(a) Which one of these atoms:
(i) contains 7 protons,
(ii) has an electronic configuration 2, 7?
(b) Write down the formula of the compound formed between C and D.
(c) predict which are: (i) metals, (ii) non-metals?

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