lesson 3

Question 1

if we were to order solids, liquids and gas where does liquid exist?

Answer 1

somewhere between gas and solid but not midway.

Question 2

why do phase changes happen?

Answer 2

because of the change in the force between molecules,

Question 3

when does a matter change from solid to liquid?

Answer 3

when energy is added and the particles move faster.

Question 4

when does a matter change from liquid to gas?

Answer 4

when more energy is added and the particles move faster.

Question 5

phase changes and how they affect density.

Answer 5

matter becomes less dense the more energy it gains so solid is the most dense, liquid is somewhere in the middle and gas is least dense.

Question 6

what are intramolecular forces?

Answer 6

the forces within a molecule. (e.g. ionic bond in NaCl)

Question 7

what are intermolecular forces?

Answer 7

the forces between molecules.

Question 8

compare intermolecular and intramolecular forces

Answer 8

intramolecular forces happen between molecules and are stronger than intermolecular forces.

intermolecular forces happen inside of a molecule.

Question 9

give examples of intramolecular forces.

Answer 9

dipole-dipole forces

london dispersion force.

Question 10

what is a dipole-dipole force?

Answer 10

forces between molecules that have a dipole moment.

Question 11

what is a dipole moment?

Answer 11

molecules with polar bonds behave like an electrical field that has a positive and negative charge side.

Question 12

what is hydrogen bonding?

Answer 12

it’s a bond between highly electronegative atom and hydrogen. and it is the strongest force.

Question 13

what is the hydrogen bond affected by?

Answer 13

electronegativity and size.

Question 14

why does size affect hydrogen bonds?

Answer 14

because it gives it gives the molecules an opportunity for a closer approach.

Question 15

what are London dispersion forces?

Answer 15

instantaneous dipole that occur accidentally in a given atom induces a similar dipole in a neighboring atom

Question 16

where do London dispersion forces occur

Answer 16

in all molecules but are most significant in larger atoms.

Question 17

what do melting and boiling points depend on?

Answer 17

on the strength of intermolecular forces. as the strength of force increase so does the melting and boiling point.

Question 18

compare dipole-dipole force to London dispersion force.

Answer 18

dipole-dipole: only in polar molecules that can have a dipole moment and smaller the size the stronger the bond.
london dispersion force: happens in all molecules (even non-polar) and is more common in larger molecules.

Question 19

properties of liquid state:

Answer 19

low compressibility, not rigid, high density.

Question 20

what are some things that are affected by intermolecular forces in liquids?

Answer 20

surface tension and capillary reactions and viscosity.

Question 21

what is surface tension?

Answer 21

the resistance of a liquid to increase its surface area.

Question 22

how does intermolecular forces affect surface tesion?

Answer 22

larger the intermolecular force, then the higher the surface tension.

Question 23

what role does intermolecular forces play in surface tension?

Answer 23

the forces between molecules hold the molecule from 3 different sides creating a surface.

Question 24

what is capillary reaction?

Answer 24

rising of liquid in a narrow tube.

Question 25

what are cohesive and adhesive forces.

Answer 25

cohesive: between the molecules of the liquid leading to the convex meniscus.
adhesive: between the molecules of the liquid and container leading to a concave meniscus.

Question 26

what is viscosity?

Answer 26

the resistance of a liquid to flow.

Question 27

types of solids? + example.

Answer 27

amorphous: disordered structure such as glass.
crystalline: ordered structure such as rock salt.

Question 28

components of solid structure,

Answer 28

lattice: a 3D system that points to how the components make up the substance.
unit cell: makes up the lattice.

Question 29

types of unit cell. and what it is made of.

Answer 29

simple cube -> corners only
body-centered cube -> in the corners and the center.
face-centered cube -> in the corner and each face.

Question 30

bragg equation.

Answer 30

n * (wave length) = 2 d sin angle

Question 31

types of crystalline solids and what they are made of. + examples

Answer 31

ionic solids -> ions are the point of the lattice. NaCl
molecular solids -> molecules at the points of the lattice. ice
atomic solids -> atoms at the point of the lattice. daimond

Question 32

classification of atomic solids.

Answer 32

metal -> metal atoms, delocalized non-directional covalent bond
network -> non-metal atoms, directional covalent bond
group 8A -> group 8A atoms -> london dispersion forces.

Question 33

classification of molecular solids and ionic solids.

Answer 33

molecular solids: discrete molecules -> dipole-dipole and london dispersion forces.
ionic solids: ions -> ionic.

Question 34

closest packing model

Answer 34

the way that uniform metal spheres are packed in a layer.

Question 35

types of closest packing model

Answer 35

abab -> hexagonal closet packing.

abc abc -> cubic closet packing.

Question 36

eqaution for radium of metal atom and length of an edge in unit sphere.

Answer 36

r * 8^1/2

Question 37

characteristics of bonding models for metals.

Answer 37

must conduct electricity and heat.
is non-directional and strong.
which means difficult to separate but easy to move.

Question 38

bonding models for metals.

Answer 38

electron sea model, molecular orbital model. band theory.

Question 39

what is an electron sea model. what characteristics does it agree with.

Answer 39

group of cations is found in a sea of valance electrons.

conductivity. and the ability to hammer and pull wires.

Question 40

what is the molecular orbital model.

Answer 40

valance electrons from molecular orbitals that travel around the metal crystal.

Question 41

what is band theory used for?

Answer 41

to explain the properties of metals and other materials.

Question 42

what other theory does band theory follow.

Answer 42

molecular orbital model as the number of molecular orbits = the number of overlapping atomic orbitals.

Question 43

what type of bonding is in the band theory.

Answer 43

is delocalized mobile electrons that are responsible for the conductivity of heat and electricity.

Question 44

what are band orbitals. how do they work?

Answer 44

a bunch of closely spaced orbitals that allow the electrons to move freely between them
electrons partially fill the bands so they are free to travel.

Question 45

what are conducting bonds.

Answer 45

molecular orbitals that have conducting electrons.

Question 46

what are metal alloys

Answer 46

substances that have a mix of element and metallic properties.

Question 47

types of alloys and example

Answer 47

substitutional alloy -> host metal atoms are replaced by another atom that is similar in size. (e.g. brass )
interstitial alloy -> in the closest packed metal structure are occupied by smaller atoms.