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Classification of Solids and Unit Cells
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This lesson covers the classification of solids, unit cell and their types i.e. SC, FCC, BCC, ECC. Also, one numerical has been discussed on the determination of formula of a compound. Picture Credits: NCERT Physics book

Anirudh Walia is teaching live on Unacademy Plus

Anirudh Walia
Chemistry Educator || YouTube Channel: Anirudh Walia, 2 Lac+ Subscribers, 10 Million+ views

U
Unacademy user
PK
super.....thanku sir
A
Sir I ask the question. A crystalline solid forming cubic lattice is made of two elements'A' and 'B'. Atoms of 'A' are present at corner and atoms of 'B' at face- centres. If all atoms along one of the body diagonal are missing, then the simplest formula of the solid is
Mohammad Umar
a year ago
AB3
Anshuli Vaths
10 months ago
I think it would be AB4
Tony STARLORD
6 months ago
AB3
A
Sir I ask the question. A crystalline solid forming cubic lattice is made of two elements'A' and 'B'. Atoms of 'A' are present at corner and atoms of 'B' at face- centres. If all atoms along one of the body diagonal are missing, then the simplest formula of the solid is
Sir sound bohot dheemi hai
Sir sound bohot dheemi hai
Sd
how can we identify whether a substance is crystalline or amorphous
  1. Solid State Anirudh Walia


  2. About me B.Tech (final year) Mechanical Engineering, VIT Vellore Follow me on Unacademy at: Course fees : CONTRIBUTE (optional) Rate , review, recommend or share the lessons. https://unacademy.com/user/anirudhw28 e Doubt/feedback/query in comment section.


  3. Course Targeted for Class XII Jee Advanced , Jee Main etc. AIIMS, NEET etc.


  4. Lesson 1 Topics covered e Classification of solids Unit cells and its types


  5. Solids Solids are the chemical substances which are characterised by define shape and volume, rigidity, high density, low compressibility. The constituent particles (atoms, molecules or ions) are closely packed and held together by strong interparticle forces Types of Solids The solids are of two types: Crystalline solids and Amorphous solids.


  6. S.No Crystalline solid Amorphous solids These doesn't have any regular arrangement of the constituent particles in space Theseare super cooled liquids or pseudo soilds. These have short order arrangement of particle. These have definite and regular arrangement of the constituent particles in space. 2 These are true solids. 3 These have long order arrangement of the particles. These are anisotropic in nature, i.e, their physical These are isotropic in nature i.e., their physical properties are different in different directions. propeties are same in all the directions. 5 They have sharp melting points. 6 They undergo a clean cleavage when cut. They melt over a certain range of temperature. They undergo irregular cleavage when cut.


  7. Type of Solid Intermolecular forcesProperties Examples Ionic Brittle, hard high MeltingNaCI, KCI, MgCl2 lon-Ion forces Dispersion /H-bond Soft, low melting non- Molecular forces/Dipole-Dipole conducting Hard: High melting point conducting Covalent network Covalent bonds C-Diamond SiO2 Variable hardness and meltingNa, Zn, Cu, Fe ness and meltin Metallic Metallic bonds


  8. Unit cell e The smallest geometrical portion of the crystal lattice which can be used as repetitive unit to build up the whole crystal is called unit cell


  9. Types of Unit Cell (i) Simple or primitive Unit cell: In which the particles are present at the corners only. Fig. 1.8: In a simple cubic unit cell. each corner atom is shared between 8 unit cells.


  10. In al, since each cubic unit cel has 8 atoms on its corners. the total number of corners, the total nunm atoms in one unit cell is 8 -= 1 atom. 8