Bonding 3

Question 1

Seven types of crystal systems

Answer 1

Cubic, tetragonal, hexagonal, rhombohedral, orthorhombic, monoclinic, triclinic

Question 2

Cubic NaCl

Answer 2

Cell edges: a = b = c

Cell angles: alpha = beta = gamma = 90 degrees

Question 3

Tetragonal Hg(CN)2

Answer 3

Cell edges: a = b x= c

Cell angles: alpha = beta = gamma = 90 degrees

Question 4

Hexagonal PbI2

Answer 4

Cell edges: a = b = c x= d
Cell angles: alpha = beta = gamma = 120 degrees
The edge d is perpendicular to the plane described by a, b, and c

Question 5

Rhombohedral NaNO3

Answer 5

Cell edges: a = b = c

Cell angles: alpha = beta = gamma x= 90 degrees

Question 6

Orthorhombic K2CrO4

Answer 6

Cell edges: a x= b x= c

Cell angles: alpha = beta = gamma = 90 degrees

Question 7

Monoclinic K3Fe(CN)6

Answer 7

Cell edges: a x= b x= c

Cell angles: alpha = gamma = 90 degrees, beta x= 90 degrees

Question 8

Triclinic CuSO4•5H2O

Answer 8

Cell edges: a x= BCM = c

Cell angles: alpha x= beta x= gamma

Question 9

Simple cubic primitive unit cell (P)

Answer 9

Contains only atoms at the corners

Question 10

Body-centered unit cell (bcc)

Answer 10

Contains atoms at the corners as well as at the center of the unit cell

Question 11

Face-centered unit cell (FCC)

Answer 11

Contains atoms at its corners and in the center of each face

Question 12

Four types of crystalline solids

Answer 12

Ionic solids
Covalent solids
Molecular solids
Metallic solids

Question 13

Ionic solids

Answer 13

Made of (+) & (-) ions arranged in regular arrays; each job is surrounded by ions of the opposite charge
Hard brittle, and have high melting and boiling points; poor conductors of electricity

Question 14

Covalent solids

Answer 14

Made of atoms held together by very strong covalent bonds; very hard and high melting points; usually poor conductors of heat and electricity

Question 15

Molecular solids (H2O, sucrose, I2, P4)

Answer 15

Made of neutral atoms; held together by dipole forces or dispersion forces; soft and poor conductors of heat and electricity

Question 16

Metallic solids

Answer 16

Are made of one closely packed metal element; free valence e- circulate soured metallic cations making them goof electricity and heat conductors; high melting points

Question 17

Close-packed structures

Answer 17

When in some substances, the atoms are packed together as closely as possible

Question 18

Tetrahedral hole (t-hole)

Answer 18

Void created four spheres (3 in the 1st and 1 above) create a regular tetrahedron

Question 19

Octahedral holes (o-holes)

Answer 19

Six spheres (3 in 1st layer and 3 in 2nd layer with layers offset by 60 degrees)

Question 20

Triangular hole

Answer 20

Between 3 adjacent spheres in the same layer

Question 21

Size of holes

Answer 21

Triangular< tetrahedral< octahedral

Question 22

Hexagonal close packing

Answer 22

When sphere of 3rd layer lie directly above spheres of 1st layer

Question 23

If there are N atoms jn a crystal

Answer 23

There are N O-holes and 2N T-holes

Question 24

Cell volumes and length cubic-close packing

Answer 24

L = 2r
V = L^3 = 8r^3

Question 25

Cell volumes body-centered cubic cell

Answer 25

``` L = (4/sqroot(3))r V = ((4/sqroot(3))r)^3 = (64/3•sqroot(3))r^3 ```

Question 26

Cell volume face centered cell

Answer 26

``` L = (4/sqrt(2))r V = ((4/sqrt(2))r)^3 = (32/sqrt(2))r^3 ```

Question 27

Coordination number (CN)

Answer 27

The number of an atom or ion's closest neighbors within the lattice; 1-6; smaller the surrounding atom and larger the center atom usually the higher the CN

Question 28

Cohesive energy

Answer 28

The difference in energy between free ions and a solid

Question 29

Lattice energy

Answer 29

The sum of the energies of interaction of the ions in a crystal

Question 30

Madelung constant

Answer 30

Compressibility data that is used to theoretically evaluate the coulombic interactions in a lattice

Question 31

Born-Haber Cycle

Answer 31

A calculation of the total energy of a crystal determined by considering all of its formation steps and including the lattice energy contribution