CHM 141 final Flashcards
conversion from one state of matter to another
Phase change
the change in enthalpy to melt a solid into a liquid
heat of fusion
the change in enthalpy to turn a liquid into a gas
heat of vaporization
the change in enthalpy to change a solid to a gas without passing through the liquid phase
heat of sublimation
vaporization + fusion =
sublimation
what equation should you use for the line B-C on a heating curve? (flat line)
q =m*heat of vaporization/ heat of fusion
what equation should you use for the line E-F on a heating curve? (increasing line)
q = mCs delta T
The temperature beyond which a gas cannot be compressed/ the highest temperature a liquid can exist as a liquid
Critical Temperature
Critical temperature—–with increasing intermolecular forces
increases
the pressure required to liquify a substance at critical T
Critical Pressure
occurs when critical T and P are surpassed and liquid and gas phases are indistinguishable from each other
Supercritical fluid
the pressure exerted by a vapor on the surface of a liquid during dynamic equilibrium,
Vapor Pressure
when two opposing processes are occurring simultaneously
dynamic equilibrium
True or false the relationship between vapor pressure and temperature is linear?
False, they do generally increase as the other increases but it is not linear
liquids that easily evaporate with high vapor pressures and low intermolecular forces
Volatile liquids
When the vapor pressure of a substance = the external pressures acting on the surface of the liquid where thermal E is enough to break intermolecular forces and create a gas
Boiling point
does boiling point increase or decrease at higher pressures?
Increases at higher pressures
the boiling point of a substance at 1 atm
normal boiling point
where all states of matter exist in equilibrium
triple point
solids with a ‘sea’ of delocalized valence electrons that conduct heat and electricity well
metallic solids
solids held together by cation and anion attractions, don’t conduct electricity well and are brittle
ionic solids
solids held together by a network of covalent bonds
covalent-network solids
individual molecules held together by weak intermolecular forces, soft with low melting points
molecular solids
chains of carbon bonded to adjacent chains held together by intermolecular forces, more flexible than other solids
polymers
solids where the dimensions have been reduced to 1-100 nm with unique properties
nanomaterials
solids with atoms in an arranged and orderly repeating pattern
crystalline solids
solids with random and cluttered atom arrangments
amorphous solids
a small repeating unit in a crystalline solid
unit cell
how is the structure of a crystalline solid defined?
by the shape and size of its unit cell
AND
by the arrangement of atoms in the unit cell
the blue print to fill in the unit cell, the arrangement of points that the unit cell will fill
crystal lattice
what are the five types of two-dimensional lattices
square lattice
rhombic lattice
hexagonal lattice
oblique lattice (most common)
rectagonal lattice
lattice cube with lattice points only at the points of a cube
primitive lattice cube
lattice cube with lattice points at the corners and one at the center of a cube
body-centered lattice cube
lattice cube with lattice points at the corners, center and on each face of a six-sided cube
face centred lattice cube
the arrangement of atoms on the lattice points in a unit cell
motif
material that contain more than one element and have properties of metals
alloy
a second element of similar size replaces a metal atom
substitutional alloy
a second atom of smaller size replaces a metal atom
interstitial alloy
compounds/ alloys with a specific order
intermetallic compound/ alloy
properties that depend on the amount of substance present
extensive properties
properties that are independent of the amount of substance present
intensive properties
M (mega)
10^6
k (kilo)
10^3
c (centi)
10^-2
m (mili)
10^-3
micro (little u thing)
10^-6
n (nano)
10^-9
p (pico)
10^-12
suffix for 4
tetra-
suffix for 5
penta-
suffix for 6
hexa-
suffix for 7
hepta-
if you are given the masses of two isotopes how do you find the abundance?
(atomic mass of element- istope mass 1)/ isotope mass 2 - isotope mass 1
if two isotopes are XYS 231 and XYS 233 and the original elements mass is 234 which is more abundant?
isotope 233 is more abundant because it is closer to the atomic mass of XYS
E of a photon =
hc/ wavelength
h=
6.62610^-34 Js
c= speed of light
2.99*10^8 m/s
how does effective nuclear charge change from left to right across the periodic table?
it increases as atoms become smaller
how does ionization energy change across the periodic table from left to right?
it increases across the periodic table and decreases top to bottom
the energy required to remove an electron from an atom
ionization energy
is moving up on an energy emission and absorption graph an emission or absorption?
absorbtion (ex: 1-3 or 2-4)
what is an allowed number for the quantum number l?
n-1 to 0
what is an allowed quantum number for the quantum number m
-l to +l
what are the allowed numbers for the magnetic spin quantum number?
+1/2 and -1/2
the net charge experienced by an electron in a many-electron atom
effective nuclear charge
are anions smaller or bigger than their neutral atom?
bigger, they have more electrons
what is the Rydberg constant?
RH = 1.096776*10^7 m
what is the rydberg equation?
1/ wavelength = RH (1/ n^2 2 - 1/n^2 1)
how many s orbitals are there?
1
how many p orbitals are there?
3
how many d orbitals are there?
5
how many f orbitals are there?
7
lowest energy orbitals are filled first in an electron configuration
aufbau principle
electron orbitals must all have at least one electron before pairing can begin
Hunds rule
no more than 2 electrons (with opposite spins) can occupy the same orbital
pauli exclusion principle
why are metals so closely packed together?
because of the sea of delocalized electrons that are shared by the metal cations, metals don’t have enough valence e for localized bonds
how does the MO theory explain the trend in decreasing boiling/melting points after the 6th metal in transition metals?
Antibonding MOs decrease bond strength and bonding MOs increase bond strength. Initially in the transition metals bonding orbitals are filled but as antibonding orbitals are filled the bond strength decreases and decrease the melting/boiling point
why are electron bands formed?
as link/chains of atoms increase the MOs grow closer together to form stacks of antibonding and bonding bands
forms from bonding MOs
valence bands
forms from antibonding MOs
conduction bands
what is the most favorable/ stable arrangement of ionic solids?
those where cation-cation and anion-anion distance are maximized to reduce repulsion
of cations/# of anions =
coordination of anion/coordination of cation
are covalent network solids stronger or weaker than molecular solids?
stronger, covalent bonds are stronger than intermolecular forces
non-metallic solids that can conduct well but not as well as metals
semi-conductors
semiconductors with one type of atom (group 4A)
elemental semiconductors
semiconductors with more than one type of atom
compound semiconductors
the process of adding impurity atoms to semi conductors to affect conductivity
semiconductor dopping
N-type semi conductors
negative, more electrons added
p-type semi conductors
positive, less electrons (less electrons leaves holes in the valence bands)
how do you name an ionic compound?
you keep the name of the cation and change the ending of the anion to ide
how do you name a covalent compound?
use the prefixes unless the first atom has only one of it (never add mono- to the beginning) also change the ending of the second atom to -ide
how do you name a binary acid (H+ one other atom)
add hydro to the beginning and ic to the end of the non-metal
how do you name oxyacids? (with oxygen)
-ate endings change to -ic and -ite endings change to -ous + the word acid at the end
chains of monomers together with a very high molecular weight
polymers
soft, can be reshaped and typically can be recycled, no cross-links
thermoplastics
formed by irreversible chemical processes so they typically cannot be reshaped, cross-links make them stronger
thermosets
rubbery solids that re take their shape after being bent/folded
elastomers
a kind of polymerization where multiple bonds are broken/ opened for monomers to join together
addition polymerization
a kind of polymerization where monomers are joined by the removal of a smaller atom between them, usually H + OH-
condensation polymerization
are polymers usually crystalline or amorphous? and why?
they are usually amorphous because they are made of monomers of different weights
the degree of structure in a solid
crystallinity
if a polymer is more dense will it have a high or low crystallinity?
it will have a high crystallinity (more dense = more regularity)
materials where their dimensions have shrunk to 10-100nm
nanomaterials
what makes metals more reactive when they are on the nanoscale?
the sea of electrons present in a metal meets the confines of the material as it has shrunk, or in other words it meets a “shore”
Explain the trends in bonding atomic radii across and down the periodic table
Bonding atomic radii decreases from left to right across the table and increases down the periodic table
it increases down the periodic table because quntum number decides size
what is lattice energy?
lattice energy is the energy required to turn one mol of a substance into a gas
the ability for an atom to attract eletrons to itself
electronegativity
what are the trends for electronegativity?
Increases (negatively) across the table
the greater the difference in electronegativity the more — the bond is
polar
the greater the difference in electronegativity the more — the bond is
polar
energy is — when bonds are formed
released
energy is — when bonds are broken
used
q + w=
Change in internal energy
system absorbs heat from the surroundings
endothermic (feels cold)
system releases heat to the surroundings
exothermic (feels hot)
a property whose value does not depend on the path taken to reach that specific value
state funcion
H =
E + P*V
how do you calculate work?
w = -p *change in volume
formula for ammonia
NH4 +
hypochlorite
ClO -
chlorite
ClO2 -
chlorate
ClO 3 -
perchlorate
ClO4 -
nitrite
NO2 -
nitrate
NO3 -
nitrate
NO3 -
sulfate
SO4 2-
Sulfite
SO 3 2-
phosphate
PO4 3-
what are the diatomics?
H2 N2 F2 O2 I2 Cl2 Br2
what elements + compounds are always soluble?
Li +, K+, Na+, NH4 +, NO3 -
what are Cl- , Br - and I- insoluble with?
Ag 2+, Hg2 2+, Pb2+
what makes sulfate insoluble?
Ag, Pb, Ca, Sr, Ba
what must hydrogen be bonded to to induce hydrogen forces?
O, N or F
