Definitions [6]
A solid is defined as the form of matter, which possesses rigidity, have a definite volume, mass and shape. These characteristics are due to the existence of strong forces of attraction among the constituent particles of the solid.
Define the term ‘amorphous’.
The solids which do not possess the repeating ordered arrangement of atoms or ions are called amorphous solids.
Define the following term:
Ferromagnetism
Ferromagnetism is defined as the phenomenon in which substances, such as iron, cobalt and nickel, are strongly attracted by a magnetic field. Such substances are called ferromagnetic substances.
A pure semiconductor with very low but finite electrical conductivity is called an intrinsic semiconductor.
The process by which impurities are introduced into semiconductors to enhance their conductivity is called doping.
A doped semiconductor, having higher conductivity than a pure intrinsic semiconductor, is an extrinsic semiconductor.
Theorems and Laws [1]
Name the law or principle to which the following observations confirm:
When 9650 coulombs of electricity is passed through a solution of copper sulphate, 3.175 g of copper is deposited on the cathode (at. wt. of Cu = 63.5).
Faraday’s first law of electrolysis: The mass of a substance deposited or liberated at an electrode is directly proportional to the quantity of electricity passed through the electrolyte.
Given: Charge passed = 9650 C
Atomic mass of Cu = 63.5
Valency of Cu in CuSO4 = 2
Equivalent mass of Cu = `63.5/2` = 31.75
Now, Mass deposited = `9650/96500 xx 31.75`
= 0.1 × 31.75
= 3.175 g
Key Points
Motion of electrons generates a magnetic field — each electron behaves like a tiny bar magnet with a magnetic moment measured in Bohr Magneton (μ_B) = 9.27 × 10⁻²⁴ A m².
| Type | Nature | Electron Configuration | Examples |
|---|---|---|---|
| Diamagnetic | Weakly repelled by magnetic field; magnetised in opposite direction | All electrons paired | NaCl, H₂O, N₂, C₆H₆, F₂, benzene |
| Paramagnetic | Weakly attracted by magnetic field; magnetised in same direction | Unpaired electrons; lose magnetism when field removed | O₂, Cu²⁺, Fe³⁺, Cr³⁺ |
| Ferromagnetic | Strongly attracted; can be permanently magnetised (all domains align in field direction) | Unpaired electrons + aligned domains | Fe, Co, Ni, Gd, CrO₂ |
Solids are classified into three groups based on conductivity:
| Type | Conductivity (Ohm⁻¹ m⁻¹) | Band Gap | Reason | Examples |
|---|---|---|---|---|
| Metallic conductors | 10⁴ – 10⁷ (very high) | No band gap (overlapping s & p bands) | Motion of electrons | Cu, Al, Ag |
| Insulators | 10⁻²⁰ – 10⁻¹⁰ (very low) | Large (forbidden zone) | Electrons cannot cross | Diamond, wood, rubber |
| Semiconductors | 10⁻⁶ – 10⁴ (moderate) | Small | Motion of interstitial electrons/holes | Si, Ge |
Conductivity of metals decreases with increase in temperature; conductivity of semiconductors increases with temperature.
Important Questions [33]
- What is the Role of the Following Compound - Caf2 in Metallurgy of Aluminium ?
- What is the Hybridisation of Carbon Atom in Diamond and Graphite?
- The Relation a ≠ b ≠ c and α ≠ β ≠ γ Represents Which Crystal System?
- Calculate the Number of Atoms Present in 2 Gram of Crystal Which Has Face-centred Cubic (Fcc) Crystal Lattice Having Edge Length of 100 Pm and Density 10
- Which of the Following Parameters Are Correct for Triclinic Lattice?
- An Ionic Crystal Lattice Has Limiting Value of Radius Ratio as 0.414 to 0.732; the Co-ordination Number of Its Cation is
- Describe triclinic crystal lattice with the help of a diagram.
- An Ionic Crystal Lattice Has `R^+/R` Radius Ratio of 0.320, Its Co-ordination Number is __
- Niobium Crystallises as Body Centred Cube (Bcc) and Has Density of 8.55 Kg / Dm-3 . Calculate the Attomic Radius of Niobium.
- Represent a Cell Consisting of Mg2+ | Mg Half Cell and Ag+ | Ag Half Cell and Write the Cell Reaction.
- A metal crystallises into two cubic faces namely face centered (FCC) and body centered (BCC), whose unit cell edge lengths are 3.5 Å and 3.0 Å respectively. Find the ratio of the densities of FCC and BCC.
- Silver crystallises in FCC structure. If density of silver is 10.51 gcm-3, calculate the volume of unit cell.
- In Body Centred Cubic Structure the Space Occupied is About
- Face centred cubic crystal lattice of copper has density of 8.966 g.cm-3. Calculate the volume of the unit cell.
- Number of Types of Orthorhombic Unit Cell is ___________.
- A unit cell of iron crystal has edge length 288 pm and density 7.86 g.cm-3. Find the number of atoms per unit cell and type of the crystal lattice.
- How many atoms constitute one unit cell of a face-centered cubic crystal?
- Gold occurs as face centred cube and has a density of 19.30 kg dm-3. Calculate atomic radius of gold. (Molar mass of Au = 197)
- The Density of Silver Having an Atomic Mass of 107.8 G Mol- 1 is 10.8 G Cm-3. If the Edge Length of Cubic Unit Cell is 4.05 × 10- 8 Cm, Find the Number of Silver Atoms in the Unit Cell.
- Explain with reason sign conventions of ΔS in the following reaction N2(g) + 3H2(g) → 2NH3(g)
- Explain with reason sign conventions of ΔS in the following reaction CO2(g) → CO2(g)
- Face Centred Cube (Fcc) Consists of How Many Atoms? Explain
- What Are Frenkel Defect
- Define the following term: Schottky defect
- Explain Impurity Defect in Stainless Steel with Diagram
- Schottky Defects Are Observed in Which Solid Among the Following?
- Pyrolusite Ore is _______.
- Iron (z=26) is highly ferromagnetic. Explain.
- Define the following term: Ferromagnetism
- What is ferromagnetism?
- To prepare n-type semiconductor the impurity to be added to silicon should have the following number of valence electrons
- P - type semi-conductors are made by mixing silicon with impurities of ______.
- What is the Ratio of Octahedral Holes to the Number of Anions in Hexagonal Closed Packed Structure?
Concepts [13]
- Introduction to Solid State
- Amorphous and Crystalline Solids
- Crystal Lattices and Unit Cells
- Calculations Involving Unit Cell Dimensions
- Close Packed Structures of Solids
- Efficiency of Packing in Body-centred Cubic Structures
- Close Packed Structures - Formula of a Compound and Number of Voids Filled
- Number of Atoms in a Unit Cell
- Imperfections in Solids - Introduction
- Properties of Solids: Magnetic Properties
- Band Theory of Metals
- Properties of Solids: Electrical Properties
- Applications of n-type and p-type Semiconductors
