NEET-2021 XII

Solid State (Bravais Lattice) Lecture-4

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Question of The Day

Question: CuSO4 has a FCC structure .A cubic crystal of edge length 17.1mm is dissolved in water to make a 500 mL solution of pH= 5.The edge length of FCC unit cell of CuSO4 is

2+ + + -5 Cu(H2O)6 + H2O ⇋ [Cu(H2O)5(OH)] + H3O , K= 10

A. 120 Ao B. 170 Ao C. 150 Ao D. 200 Ao Unit Cell Analysis

Face Centred Unit Cell: Unit Cell Analysis

End Centred Unit Cell: Bravais Lattices Seven Crystal Systems: Seven Crystal Systems And Bravais Lattices Crystal system Edge length Angles Examples Bravais Lattices

1. Cubic a = b = c α = β = γ = 90° NaCl, KCl Simple, body centred, face centred

2. Tetragonal a = b ≠ c α = β = γ = 90° TiO2, SnO2 Simple, body centred

3. Orthorhombic a ≠ b ≠ c α = β = γ = 90° S, BaSO4, PbCO3 Simple, body centred, face- centred, end face centred 4. Monoclinic a ≠ b ≠ c α = γ = 90° Borax, S Simple, end face β ≠ 90° centred

5. Triclinic a ≠ b ≠ c α ≠ β ≠ γ ≠ 90° Boric acid, K2Cr2O7 Simple

6. Hexagonal a = b ≠ c α = β = 90° SiC, ZnO, Graphite Simple γ ≠ 120° 7. Rhombohedral a = b = c α = β = γ ≠ 90° Quartz, Cinnabar, Simple

Calcite (CaCO3) Contribution of different Lattice points Contribution of different Lattice points

Lattice Point Corner of cube Edge of cube Face of cube Body-centre

Contribution 1/8 1/4 1/2 1

Z = nc /8 + nedge /4 + nfc /2 + nbd +nbc Check Your Concept

Question: Which of the following crystalline arrangement will have at least one of the angles equals to 90o and at least two axial lengths equal? A. Orthorhombic B. Rhombohedral C. Monoclinic D. Tetragonal Check Your Concept

Question: Check Your Concept

Question: Check Your Concept

Question: Check Your Concept

Question: In a solid A atoms are present at corners,B atoms at all face centres,C atoms at all edge centres and D atoms at body centre.If all the atoms from one of the 2-fold axis of symmetry are removed,the formula of the solid would be

A. AB4C5D

B. A2B4C5

C. A2B8C5D

D. A2B8C5 Check Your Concept

Question: In a solid A atoms are present at corners,B atoms at all face centres,C atoms at all edge centres and D atoms at body centre.If all the atoms from one of the octants are removed,the formula of the solid would be?

A. A3B6C8

B. A2B3C5

C. A3B3C2 D. None Nearest Neighbours

Primitive Unit Cell: Nearest Neighbours

Primitive Unit Cell: Nearest Neighbours

Body Centred Unit Cell: Nearest Neighbours

Body Centred Unit Cell: Nearest Neighbours

Face Centred Unit Cell: Nearest Neighbours

Face Centred Unit Cell: NEET