Chapter 10: Liquids and Solids

Question 1

Condensed states

Answer 1

Liquids and solids

Question 2

Intermolecular forces

Answer 2

Forces that occur between molecules

Question 3

Dipole-dipole attraction

Answer 3

Molecules with dipole moments can attract each other electrostatically by lining up so that the positive and negative ends are close to each other

Question 4

Hydrogen bonding

Answer 4

Particularly strong dipole-dipole forces where hydrogen is bound to a highly electronegative atom, such as N, O, or F

Question 5

London dispersion forces

Answer 5

The forces, existing among noble gas atoms and nonpolar molecules, that involve an accidental dipole that induces a momentary dipole in a neighbor

Question 6

Surface tension

Answer 6

The resistance of a liquid to an increase in its surface area

Question 7

Capillary action

Answer 7

The spontaneous rising of a liquid in a narrow tube

Question 8

Cohesive forces

Answer 8

The intermolecular forces among the molecules of the liquid

Question 9

Adhesive forces

Answer 9

The forces between the liquid molecules and their container

Question 10

Viscosity

Answer 10

A measure of a liquid’s resistance to flow

Question 11

Crystalline solids

Answer 11

Solids with a highly regular arrangement of their components

Question 12

Amorphous solids

Answer 12

Solids with considerable disorder in their structures

Question 13

Lattice

Answer 13

A three-dimensional system of points designating the positions of the components (atoms, ions, or molecules) that make up the substance

Question 14

Unit cell

Answer 14

The smallest repeating unit of the lattice

Question 15

Bragg equation

Answer 15

nλ = 2d sin θ

n = integer
λ = wavelength of the x rays
d = distance between the atoms
θ = angle of incidence and reflection

Question 16

Ionic solid

Answer 16

A solid containing cations and anions that dissolves in water to give a solution containing the separated ions, which are mobile and thus free to conduct an electric current

Question 17

Molecular solid

Answer 17

A solid composed of neutral molecules at the lattice points

Bonding: Dipole-dipole and/or London dispersion forces

Question 18

Atomic solid

Answer 18

A solid that contains atoms at the lattice points

Question 19

Three types of atomic solids

Answer 19

1. Metallic - metal, delocalized covalent bonding
2. Network - nonmetal, directional covalent
3. Group 8A - group 8A, London dispersion forces

Question 20

Closest packing

Answer 20

Packing uniform, hard spheres in a manner that most efficiently uses the available space

Question 21

aba Arrangement

Answer 21

The third layer occupies positions so that each sphere in the third layer lies directly over a sphere in the first layer (Hexagonal unit cell, hexagonal closest packed structure)

Question 22

abc Arrangement

Answer 22

The third layer occupies positions so that no sphere in the third layer lies over one in the first layer (face-centered cubic unit cell, cubic closest packed structure)

Question 23

In both hcp and ccp structures, each sphere has __ equivalent nearest neighbors.

Answer 23

12

• 6 in the same layer
• 3 in the layer above
• 3 in the layer below (that form the dimples)

Question 24

How many atoms are in a face-centered cubic unit cell?

Answer 24

(8 x 1/8) + (6 x 1/2) = 4

Question 25

How many atoms are in a simple cubic unit cell?

Answer 25

(8 x 1/8) = 1

Question 26

How many atoms are in a body-centered cubic unit cell?

Answer 26

(8 x 1/8) + 1 = 2

Question 27

Alloy

Answer 27

A substance that contains a mixture of elements and has metallic properties

Question 28

Substitutional alloy

Answer 28

Some of the host metal atoms are REPLACED by other metal atoms of similar size.

Question 29

Interstitial alloy

Answer 29

When some of the interstices (holes) in the closest packed metal structure are occupied by small atoms

Question 30

Network solids

Answer 30

Atomic solids that contain strong directional covalent bonds to form a solid viewed as a "giant molecule" (e.g.: Two most common forms of carbon: graphite and diamond)

Question 31

Silica

Answer 31

The fundamental silicon-oxygen compound, which has the empirical formula SiO2, and forms the basis of quartz and certain types of sand.

Question 32

Diamond

Answer 32

Each carbon atom is surrounded by a tetrahedral arrangement, stabilized by covalent bonds.

Question 33

Graphite

Answer 33

Layers of carbon atoms arranged in fused six-membered rings. Each carbon atom in a particular layer of graphite is surrounded by the three other carbon atoms in a trigonal planar arrangement.

Question 34

Silicates

Answer 34

Salts that contain metal cations and polyatomic silicon-oxygen anions that are usually polymeric.

Question 35

Glass

Answer 35

An amorphous solid obtained when silica is mixed with other compounds, heated above its melting point, and then cooled rapidly (HOMOGENEOUS)

Question 36

Quartz

Answer 36

Based on interconnected SiO4 tetrahedra with shared oxygen atoms, composed of silica

Question 37

Ceramics

Answer 37

Made from clays (which contain silicates) and hardened by firing at high temperatures. Nonmetallic materials that are strong, brittle, and resistant to heat and attack by chemicals (HETEROGENEOUS: minutes crystals of silicates that are suspended in a glassy cement)

Question 38

Semiconductor

Answer 38

A substance conducting only a slight electric current at room temperature, but showing increased conductivity at higher temperatures

Question 39

n-type semiconductor

Answer 39

A substance whose conductivity is increased by doping it with atoms having more valence electrons than the atoms in the host crystal

Question 40

p-type semiconductor

Answer 40

A substance whose conductivity is increased by doping it with atoms having fewer valence electrons than the atoms of the host crystal

Question 41

Size of the the three holes in closest packed structures from smallest to largest

Answer 41

Trigonal

Question 42

In the closest packed structure, there are _____ as many tetrahedral holes as packed anions

Answer 42

Twice

Question 43

Vaporization/evaporation

Answer 43

The change in state that occurs when a liquid evaporates to form a gas (ENDOTHERMIC)

Question 44

Heat/enthalpy of vaporization

Answer 44

The energy required to vaporize 1 mole of a liquid at a pressure of 1 atm

Question 45

Condensation

Answer 45

The process by which vapor molecules re-form a liquid

Question 46

Equilibrium

Answer 46

When enough vapor molecules are present above the liquid so that the rate of condensation equals the rate of evaporation, thus the two opposite processes exactly balance each other

Question 47

Vapor pressure

Answer 47

The pressure of the vapor present at equilibrium

Question 48

Volatile

Answer 48

Describes liquids with high vapor pressures and evaporate rapidly from an open dish

Question 49

Vapor pressure decreases with...

Answer 49

Larger intermolecular forces and molar masses

Question 50

Vapor pressure increases with...

Answer 50

Higher temperatures

Question 51

Vapor pressure and heat of vaporization equation

Answer 51

ln(Pvap) = -(∆Hvap/R)(1/T) + C ``` T = Kelvin temperature R = universal gas constant = 8.3145 J/K • mol C = constant characteristic of a given liquid ```

Question 52

Change in Vapor Pressures and Temperatures equation

Answer 52

ln(Pvap,T1/Pvap,T2) = (∆Hvap/R)(1/T2 - 1/T1)

Question 53

Heating curve

Answer 53

A plot of temperature versus time for a process where energy is added at a constant rate

Question 54

Heat/enthalpy of fusion

Answer 54

The enthalpy change that occurs at the melting point when a solid melts

Question 55

Normal melting point

Answer 55

The temperature at which the solid and liquid states have the same vapor pressure under conditions where the total pressure is 1 atmosphere

Question 56

Normal boiling point

Answer 56

The temperature at which the vapor pressure of the liquid is exactly 1 atmosphere

Question 57

Supercooling

Answer 57

The process of cooling a liquid below its freezing point without its changing to a solid

Question 58

Superheating

Answer 58

The process of heating a liquid above its boiling point without its boiling

Question 59

Triple point

Answer 59

The point on a phase diagram at which all three states of a substance are present

Question 60

Critical temperature

Answer 60

The temperature above which the vapor cannot be liquefied no matter what pressure is applied

Question 61

Critical pressure

Answer 61

The pressure to produce liquefaction at the critical temperature

Question 62

Critical point

Answer 62

The point on a phase diagram at which the temperature and pressure have their critical values; the endpoint of the liquid-vapor line