Corundum (Al2O3) type Structure:

This type structure is exhibited by oxides of trivalent metals for examples Fe₂O₃, Al₂O₃, Cr₂O₃, Mn₂O₃ etc.

General formula is M₂O₃:

In Corundum  Structure:

O^-2 = ions forms HCP unit cell:

M⁺³ = Occupied  2/3 (66.66%) of octahedral voids (OV): and 33.33% OV are empty and TVs are 100% empty.

In Hexagonal close packing (HCP): Formula determination:

O^-2 = HCP = O₆

M⁺³=2/3 x 6 = M₄

=M₄O₆  or  M₂O₃

Related Questions:

What are the normal spinel structures?

What are the inverse spinel structures?

What are different stacking pattern of atoms in simple cubic cell (SCC) , body cubic cell (BCC) and face centred cell (FCC) unit lattice cell ?

What is the effect of temperature and pressure on crystal structure of Caesium Chloride?

What is the number of atoms on one unit cell of HCP?

If the total number of atoms per unit cell in an hcp structure and a bcc structure gets halved, then ratio of percentage voids in hcp and bcc structures is

If silver iodide crystallizes in a zinc blende structure with I- ions forming the lattice then calculate fraction of the tetrahedral voids occupied by Ag+ ions.

Sodium metal crystallizes In body centered cubic lattice with the cell edge, a= 4.29 A.What is the radius of sodium atom? (III-.JEE 1994)

A metal crystallizes into two cubic phases, face centered cubic (fcc) and body centered cubic (bcc), whose unit cell lengths are 3.5 A° and 3.0 A°, rcspcctively. Calculate the ratio of densities of fcc and bcc. (IIT-JEE 1999)

A metallic element crystallizes into a lattice containing a sequence of layers ABABAB....Any packing of spheres leaves out voids in the lattice. What percentage by volume of this lattice is empty space? ( IIT-.IEF 2006)

The coordination number of Al in the crystalline state of AlCl3 is .... (IIT-JEE 2009)

The number of hexagonal faces that are present in truncated octahedron is .... (IIT-JEE 2011)

What are structural information of Dimomd ?

What are coordination number (nearest neighbour) in a BCC at distance of (a√3/2) and next nearest neighbour at distance (a) and next to next nearest neighbour at distance (a√2) ?.

What are coordination number (nearest neighbour) in a SCC at distance of it lattice parameter (a) and next nearest neighbour at distance (a√2) and next to next nearest neighbour at distance (a√3) ?.

Rutile (TiO2) type Structure:

This type of structure is represented by TiO₂ and other example are includes MnO₂ , SnO₂ , MgF₂, NiF₂ etc 

In Rutile structure:

O^-2  = ions forms hexagonal cubic packing (HCP).

M⁺⁴ =Tetravalent cations are occupied 50 % (1/2) of octahedral voids (OV) while all the tetrahedral voids (TO) are empty.

HCP= Lattice points (LP) = O^-2= 6

M⁺⁴ ions = OV (50%) =6 x 1/2 = 3

M₃O₆ = MO₂

It means each HCP unit cell certain three (M⁺⁴ ) and  six (O^-2 )ions

Related Questions:

What are the normal spinel structures?

What are the inverse spinel structures?

What are different stacking pattern of atoms in simple cubic cell (SCC) , body cubic cell (BCC) and face centred cell (FCC) unit lattice cell ?

What is the effect of temperature and pressure on crystal structure of Caesium Chloride?

What is the number of atoms on one unit cell of HCP?

If the total number of atoms per unit cell in an hcp structure and a bcc structure gets halved, then ratio of percentage voids in hcp and bcc structures is

If silver iodide crystallizes in a zinc blende structure with I- ions forming the lattice then calculate fraction of the tetrahedral voids occupied by Ag+ ions.

Sodium metal crystallizes In body centered cubic lattice with the cell edge, a= 4.29 A.What is the radius of sodium atom? (III-.JEE 1994)

A metal crystallizes into two cubic phases, face centered cubic (fcc) and body centered cubic (bcc), whose unit cell lengths are 3.5 A° and 3.0 A°, rcspcctively. Calculate the ratio of densities of fcc and bcc. (IIT-JEE 1999)

A metallic element crystallizes into a lattice containing a sequence of layers ABABAB....Any packing of spheres leaves out voids in the lattice. What percentage by volume of this lattice is empty space? ( IIT-.IEF 2006)

The coordination number of Al in the crystalline state of AlCl3 is .... (IIT-JEE 2009)

The number of hexagonal faces that are present in truncated octahedron is .... (IIT-JEE 2011)

What are structural information of Dimomd ?

What are coordination number (nearest neighbour) in a BCC at distance of (a√3/2) and next nearest neighbour at distance (a) and next to next nearest neighbour at distance (a√2) ?.

What are coordination number (nearest neighbour) in a SCC at distance of it lattice parameter (a) and next nearest neighbour at distance (a√2) and next to next nearest neighbour at distance (a√3) ?.

Pervoskite (ABO3) type structure:

ABQ₃ is a proto type solid where A is a divalent cation  and B is a tetravalent cation.

A⁺² = Divalent cations

B⁺⁴ =Tetravalent cations

In Pervoskite structure:

A⁺² = placed at corner of cubic unit cell

O^-2 = placed at all the face centre

That means A⁺² and O^-2 ions combinelly form CCP/FCC like structure  and

B⁺⁴ = Tetravalent cations occupy the central octahedral voids (25% of total OV) i.e centre of the centre of the unit cell so general formula is ABO₃

Other examples are BaTiO₃, SrTiO₃

Related Questions:

What are the normal spinel structures?

What are the inverse spinel structures?

What are different stacking pattern of atoms in simple cubic cell (SCC) , body cubic cell (BCC) and face centred cell (FCC) unit lattice cell ?

What is the effect of temperature and pressure on crystal structure of Caesium Chloride?

What is the number of atoms on one unit cell of HCP?

If the total number of atoms per unit cell in an hcp structure and a bcc structure gets halved, then ratio of percentage voids in hcp and bcc structures is

If silver iodide crystallizes in a zinc blende structure with I- ions forming the lattice then calculate fraction of the tetrahedral voids occupied by Ag+ ions.

Sodium metal crystallizes In body centered cubic lattice with the cell edge, a= 4.29 A.What is the radius of sodium atom? (III-.JEE 1994)

A metal crystallizes into two cubic phases, face centered cubic (fcc) and body centered cubic (bcc), whose unit cell lengths are 3.5 A° and 3.0 A°, rcspcctively. Calculate the ratio of densities of fcc and bcc. (IIT-JEE 1999)

A metallic element crystallizes into a lattice containing a sequence of layers ABABAB....Any packing of spheres leaves out voids in the lattice. What percentage by volume of this lattice is empty space? ( IIT-.IEF 2006)

The coordination number of Al in the crystalline state of AlCl3 is .... (IIT-JEE 2009)

The number of hexagonal faces that are present in truncated octahedron is .... (IIT-JEE 2011)

What are structural information of Dimomd ?

What are coordination number (nearest neighbour) in a BCC at distance of (a√3/2) and next nearest neighbour at distance (a) and next to next nearest neighbour at distance (a√2) ?.

What are coordination number (nearest neighbour) in a SCC at distance of it lattice parameter (a) and next nearest neighbour at distance (a√2) and next to next nearest neighbour at distance (a√3) ?.

How to calculate radius ratio of square Voids?

How to calculate radius ratio triangular voids?

How to calculate packing fraction or packing efficiency of two dimensional (2D) hexagonal packing solid atoms?

Both CO2 and N2O are linear but dipole moment of CO2 is zero but for N2O it is non-zero, why?

The answer lies in the structure of these molecules, CO₂ is symmetrical molecule while N₂O is unsymmetrical, thus for N₂O, dipoles do not cancel each other, leaving the molecule with a resultant dipole, while the bond moment of CO₂ cancel each other, so CO₂ has no net dipole moment.

Related Questions:

Question(1): Why aqueous solution of AlCl₃ is acidic in nature ?

Question(2): What happen when aq AlCl₃ react with Acid or Base?

Question(3): Although anhydrous aluminium chloride is covalent but its aqueous solution is ionic in nature. Why?

Question(4): Arrange in increasing order of extent of hydrolysis [ CCI₄, MgCI₂, AICI₃, PCl₅, SiCI₄].

Question(5): Although Sulphur contain vacant d-orbital but SF6 does not undergo hydrolysis. Why ?

Question(6): CCl₄ can not be hydrolysed but SiCl4 can be. Why?

Question(7): What are the hydrolysis products of urea ?

Question(8): Why SF₆ is inert where as SF₄ is highly reactive towards H₂0 ?.

Question(9): Why SF₆ behave inert towards hydrolysis?

Question(10): Why PCl₃ hydrolysed while NCl₃ can not be hydrolysed?

Question(11): Why hydrolysis of NCl3 gives NH4OH and HOCl, while PCl3 on hydrolysis gives H3PO3 and HCl?

Question(12): NCl3 and PCl3 on hydrolysis give different kinds of products. These is because of

NCl3 and PCl3 on hydrolysis give different kinds of products. These is because of

(A) Attack of lone pair of water takes place to N and P respectively.

(B) Attack of lone pair of water takes place to Cl and Cl respectively.

(C) Attack of lone pair of water takes place to Cl and P respectively.

(D) None of these

Solution: (C) Their is no vacant d- orbitals hence attack of lone pair of water takes place to Cl and P respectively.

Related Questions:

Question(1): Why aqueous solution of AlCl₃ is acidic in nature ?

Question(2): What happen when aq AlCl₃ react with Acid or Base?

Question(3): Although anhydrous aluminium chloride is covalent but its aqueous solution is ionic in nature. Why?

Question(4): Arrange in increasing order of extent of hydrolysis [ CCI₄, MgCI₂, AICI₃, PCl₅, SiCI₄].

Question(5): Although Sulphur contain vacant d-orbital but SF6 does not undergo hydrolysis. Why ?

Question(6): CCl₄ can not be hydrolysed but SiCl4 can be. Why?

Question(7): What are the hydrolysis products of urea ?

Question(8): Why SF₆ is inert where as SF₄ is highly reactive towards H₂0 ?.

Question(9): Why SF₆ behave inert towards hydrolysis?

Question(10): Why PCl₃ hydrolysed while NCl₃ can not be hydrolysed?

Question(11): Why hydrolysis of NCl3 gives NH4OH and HOCl, while PCl3 on hydrolysis gives H3PO3 and HCl?