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CLASS 11—CHEMISTRY CHAPTER 6: CHEMICAL BONDING

This is a discussion on CLASS 11—CHEMISTRY CHAPTER 6: CHEMICAL BONDING within the 11th forums, part of the Classes category; CLASS 11—CHEMISTRY CHAPTER 6: CHEMICAL BONDING SHORT QUESTION ANSWER Q1. Each carbon oxygen bond in CO2 molecule is polar but ...

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    CLASS 11—CHEMISTRY CHAPTER 6: CHEMICAL BONDING

    CLASS 11—CHEMISTRY
    CHAPTER 6: CHEMICAL BONDING
    SHORT QUESTION ANSWER

    Q1. Each carbon oxygen bond in CO2 molecule is polar but the molecule as a whole is non-polar.

    Ans. carbon oxygen bond in CO2 molecule is polar but the molecule as a whole is non-polar because polarity of both double bonds cancels each other. The resultant dipole moment is therefore zero.

    Q2. Why water molecules remain associated in liquid form?

    Ans. water molecules remain associated in liquid form Due to hydrogen bond.

    Q3. What is the shape of methane molecule? Discuss brief

    Ans.Chemical formula of methane is CH4. Methane has one carbon atom which spᶟ hybridized. These hybridized orbitals from sigma bonds with four hydrogen atoms. Applying VSEPR theory its electron pair geometry and molecular shape both are tetrahedral.

    Q4. Suggest the expected shapes of SO2 and NH3 molecules with reasons.

    Ans. Sulfur has two bonded oxygen atoms and a lone pair, therefore SO2 must have non-linear or bend shape. Because lone-pair, bond pair repulsion is greater than bond-pair, bond pair repulsion. The shape of NH3 molecule must be trigonal pyramidal because nitrogen has three bonded atoms of hydrogen and a lone pair.

    Q5. Which bond is stronger whether sigma or pi?

    Ans. Sigma bond is formed due to the head-on overlap of atomic orbitals. Thermal stability of sigma bond is greater than that pi-bond, because the extent of overlap in case of sigma bond is greater.

    Q6. What are the main properties of covalent compounds?

    Ans. Properties of covalent compounds:
    i. Generally soluble in non-polar solvents.
    ii. Bad conductors of electricity
    iii. Have low melting point and boiling point.
    iv. Reactions between covalent compounds are generally slow.
    v. Covalent bond is directional in nature.
    vi. Crystal are made up of molecules.
    vii. Mostly soft and non-brittle.
    viii. May be solids, liquids or gases at room temperature.

    Q7. What type of valence exists in NH3 and NH4?

    Ans. Valence of nitrogen in case of NH3 is three while in case of NH4 it is four.

    Q8. What is a covalent bond? State two factors which influence their formation.

    Ans. Covalent bond is formed by the sharing of electrons. The elements which form covalent bonds with each other generally have unpaired electrons and close electronegativity’s. The atoms of an element can also form covalent bond with each other.

    Q9. What is the shape of the water molecule?

    Ans. Oxygen is the central atom in water molecule. It valence shell contain two lone pairs and two bond pairs. Applying VSEPR theory electron pair geometry of water molecule is tetrahedral while molecular shape is angular, bend, non-linear or v-shaped.

    Q10. Write bond on hydrogen bonding.

    Ans. “hydrogen bond is intermolecular”. There are two requirements for hydrogen bonding.
    1. One molecule must have a hydrogen atom bonded to oxygen, nitrogen, or fluorine.
    2. Second molecule must have a lone pair of electron on oxygen, nitrogen, or fluorine.

    Q11. Which bond is stronger among single and double covalent bond.

    Ans. Double bond is stronger than single bond. A single bond is always a sigma bond while pi-bond is consist of sigma and pi-bond. In order to break a double bond both sigma and pi-bonds are to be broken. Therefore bond energy for a double bond is greater that of single bond.

    Q12. What is the shape of the BCl3 molecule? What type of hybridization is there?

    Ans. Steric number for boron in BCl3 is three. It has no lone pair, thus hybridization of boron in this molecule is sp2 and its shape is trigonal planner.

    Q13. What is the nature of bonding in methane, sulfuric acid and ammonium ion?

    Ans. Methane, sulfuric acid and ammonium ion
    Methane: methane contains four sigma covalent bonds.
    Sulfuric acid contains covalent bonds. Sulfuric acid has resonating structure.

    Q14. In CS2 each carbon-sulfur bond is polar but the molecule as a whole is non-polar, give reason

    Ans. Because polarity of both double bonds cancels each other. The resultant dipole moment is therefore zero

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