- (a) 2
- (b) 4
- (c) 3
- (d) 5
Answer:
(b) 4
- (a) gain one
- (b) gain two
- (c) lose one
- (d) lose two
Answer:
(c) lose one
- (a) potassium
- (b) calcium
- (c) fluorine
- (d) iron
Answer:
(c) fluorine
- (a) ionic bond
- (b) covalent bond
- (c) coordinate bond
Answer:
(a) ionic bond
- (a) Covalent
- (b) Coordinate
- (c) Ionic
Answer:
(c) Ionic
- (a) transfer of electrons
- (b) sharing of electrons
- (c) sharing a pair of electrons
Answer:
(b) sharing of electrons
- (a) electron donors
- (b) electron acceptors
Answer:
(b) electron acceptors
- (a) halogens
- (b) metals
- (c) noble gases
- (d) non-metals
Answer:
(c) noble gases
Answer:
Atoms attain stable noble gas electronic configuration by:
- Transfer of valence electrons
- Sharing of valence electrons
This results in stable octet configuration.
Answer:
NaCl is an ionic compound.
- Water is a polar solvent → dissolves ionic compounds.
- Carbon tetrachloride ((CCl_4)) is non-polar → does not dissolve ionic compounds.
Hence NaCl dissolves in water but not in (CCl_4).
Answer:
Atoms tend to attain eight electrons in valence shell for stability.
This is called:
Octet Rule
Example
Sodium
Electronic configuration:
Sodium loses one electron:
It attains Neon configuration.
Chlorine
Electronic configuration:
Chlorine gains one electron:
It attains Argon configuration.
Answer:
Main types of chemical bonds are:
- Ionic bond
- Covalent bond
- Coordinate covalent bond
These bonds differ in:
- mode of formation
- strength
- physical properties
(a) Incorrect statement: Ionic compounds dissolve in non-polar solvents. Correct statement: Ionic compounds dissolve in polar solvents such as water. This is because ionic compounds consist of charged ions, and polar solvents have molecules with partial positive and negative charges that can surround and separate these ions through a process called solvation. Non-polar solvents lack this ability and therefore cannot effectively dissolve ionic compounds. (b) Incorrect statement: Covalent compounds conduct electricity in molten state. Correct statement: Covalent compounds generally do not conduct electricity in either molten or aqueous state because they do not form free ions or charged particles that are necessary for electrical conduction. In contrast, ionic compounds conduct electricity in both molten and aqueous states because the ions become mobile and can carry electric current through the solution or molten liquid.
| Bond Type | Formation |
|---|---|
| Ionic bond | Transfer of electrons |
| Covalent bond | Sharing of electrons |
| Coordinate bond | Sharing of electron pair by one atom |
Carbon Configuration
Oxygen Configuration
Carbon shares two pairs of electrons with each oxygen atom.
Structure:
Two double covalent bonds are formed.
| Compound | Bond Type |
|---|---|
| (CaCl_2) | Ionic |
| (H_2O) | Covalent |
| (CaO) | Ionic |
| CO | Coordinate + Covalent |
| KBr | Ionic |
| HCl | Covalent |
| (CCl_4) | Covalent |
| HF | Covalent |
| (CO_2) | Covalent |
| (Al_2Cl_6) | Coordinate covalent |
Correct answer:
(b) hard and brittle
(a)
Answer:
Oxidation
(loss of electron)
(b)
Answer:
Reduction
(gain of electrons)
| Characteristic | Compound Type |
|---|---|
| Soluble in non-polar solvent | Covalent |
| Fast reactions in aqueous solution | Ionic |
| Non-conductor | Covalent |
| Crystalline solid at room temperature | Ionic |
Given:
- X → atomic number 20 → Calcium
- Y → atomic number 8 → Oxygen
Compound formed:
Calcium transfers two electrons to oxygen.
Result:
| (MgCl_2) (Ionic) | (CH_4) (Covalent) |
|---|---|
| Formed by electron transfer | Formed by electron sharing |
| Strong electrostatic attraction | Weak intermolecular force |
| Conducts electricity in molten state | Does not conduct electricity |
| High melting point | Low melting point |
Answer:
Noble gases possess completely filled valence shell.
Hence they:
- neither gain electrons
- nor lose electrons
Therefore they are chemically inert.
| Ionic Compounds | Covalent Compounds |
|---|---|
| Formed by electron transfer | Formed by electron sharing |
| Strong electrostatic force | Weak intermolecular force |
| Hard and brittle | Soft and waxy |
| High melting point | Low melting point |
| Conduct electricity in molten state | Non-conductors |
| Soluble in polar solvents | Soluble in non-polar solvents |
| Fast ionic reactions | Slow molecular reactions |
(a) Two Covalent Bonds
(b) One Ionic Bond
(c) Two Covalent + One Coordinate Bond
(d) Three Covalent Bonds
(e) Coordinate Bond
(a)
Simple molecular species containing coordinate covalent bonds are generally non-ionic and poor conductors.
Coordination compounds that form ionic salts may contain complex ions and can conduct electricity in aqueous solution.
(b)
Ionic bond is stronger than hydrogen bond.
(c)
Covalent bonds form by sharing of electrons between atoms. In a coordinate covalent bond, the shared pair comes from one atom.
(d)
Correct statement.
- Loss of electrons → oxidation
- Gain of electrons → reduction
(e)
Electrons not involved in bonding are called:
Lone pair (non-bonding) electrons
(a) Physical State
Coordinate-bonded molecular compounds can be solids, liquids or gases.
Ionic coordination complexes are usually crystalline solids.
(b) Electrical Conductivity
Molecular coordinate compounds are poor conductors.
Ionic coordination complexes conduct in molten state or in aqueous solution when ions are present.
(c) Melting Point
Molecular coordinate compounds have low to moderate melting points.
Ionic coordination salts generally have higher melting points.
(d) Solubility
Molecular coordinate compounds may dissolve in non-polar or weakly polar solvents depending on structure.
Ionic coordination salts are generally soluble in polar solvents such as water.
(e) Reactions
Molecular coordinate compounds undergo covalent or molecular reactions.
Coordination complexes may undergo ligand exchange, ionisation and complexation reactions.
# (a) Carbon in (CO_2)
# (b) Manganese in (MnSO_4)
# (c) Nitrogen in (HNO_3)
# Important Summary
Ionic Bond
- Electron transfer
- Metal + Non-metal
Covalent Bond
- Electron sharing
- Non-metal + Non-metal
Coordinate Bond
- Shared electron pair donated by one atom
Oxidation
Loss of electrons
Reduction
Gain of electrons
Noble Gases
- Stable octet configuration
- Chemically inert
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