Exam 3 Flashcards
Specific heat capacity
amount of (thermal) energy required to change temperature of 1 degree Celsius of 1.0 g material
Exothermic
Delta T < 0
-q
Endothermic
Delta T > 0
+q
calorimetry
the study of heat flow accompanies a chemical process
When does Delta H=q
As long as q is measured with masses equivalent to make ratios in balanced rxn ie Ch4(16g/mol)+2O2 etc eqn question: 16gCh4 in excess O2
-qrxn =
+qsoln
+qsoln=
(mcDeltaT)soln
light admitted at specific energy values in the spectrum, light source produced light of
only specific (or certain) wavelengths
Bohr’s model of the H atom
Neils Bohr
-The presence of 4 distinct bands of light in the visible region of the atomic emission spectrum for hydrogen is based on the way energy reacts with certain electorons
how long do electrons stay in an excited state
short time
+E to system
e- jumps up
from system
e- jumps down
Neils bohr’s model to explain the lines spectrum of hydrogen
based on classical physics explaining macro scale phenomenon: 4 points
four points of Neil boars model
- only specific orbits allowed e- resides on orbits
- e- in orbit has specific E
-e- won’t radiate E
-e- won’t spiral into nucleus - e- jump low –> high must absorb E
e- jumps high –>low must emit E - use precipitate number (n) to identify orbits
e- wants to be
in lowest E
Quantized E
specific amount needed for a specific transition Exact! no more no less
e- from high states to low
can make stops
e- from low states to high
can’t make stops
Delta energy and wavelength
as E goes up wave length goes down
frequency and wavelength
as wavelength goes up frequency goes down
frequency and delta energy
as E goes up frequency goes up
Spectrum
400 0
V I B G Y O R
boars model of H atom was good because
explained absorption and emissions
-H atom only has 1 e-
boars model of H bad because
- only explains few (one electron) systems
- violates classical physics
- violates uncertainty principle:
what was the uncertainty principle
can’t know both E and position at the same time
treating electrons as waives in an atom
- particle/wave duality of light
- particle/wave duality of e-
how does light behave
like a particle
how fast does the wave travel through space at
speed of light
frequency)(wave length
photon
light particle, smallest packet of energy
E=h(frequency)
how does matter emit and absorb energy
in units of hu’s
plancles constant
h
wave calc
c=(length)(frequency)
particle calc
e=h(frequency)
what is light
the one type of electromagnetic radiation (emr). Oscilating orthogonal wave traveling through space at c (constant speed)
waves interacting with atoms
Dif waves react Dif w atoms
Quantum mechanics
treats e- behavior as a wave
-Describe e- wave functions equation
Regions in space with high probability of electron density
orbitals
how many electrons does each orbital hold
2
S orbital
probability density is spherical
-only one allowed
P orbital
prob. density is peanut shaped
- only 3 allowed
D orbital
Prob density is doubled up or doughnut
-only 5 allowed
F orbital
prob density is fancy
-only 7 allowed
Energy related to orbitals
1 S 2 S P 3 S P D 4 S P D F 5 S P D F 6 S P D F 7 S P D F
n
principle quantum number
-Energy level
l
angular momentum shape
Ml
magnetic orientation
Letter related to l number
S 0 P 1 D 2 F 3 Have a value of n, l is allowed from 0 up to n-1
L number related to Ml number
0 0
1 -1,0,1
2 -2,-1,0,1,2
3 -3.-2,-1,0,1,2,3
Pauli exclusion principle
no two e- can have the same set of quantum numbers
how to name a quantum
(n,l,Ml,Ms)
Ms
electron
Hunds rule
maximize parallels spins before spin pair
Degenerate
same enegy
AUFBAV principle
fill orbitals from low E–>high E
Noble gasses
Stable because of electron conferrence are composed of full and closed shells
Valence electron
Do all the work: gained, lost, involved in reactions, and bonding
Transition metals
Don’t follow an 8 valence electron rule; follow an 18 valence electronic rule
What are the exceptions to transition metals following the 18 valence e rule
Cr
Mg
Cu
Ag
Spin pairing energy
When energy change costs energy
-delta E between orbits
Energy to promote v energy to pair
Less energy to promote than to pair
Atom to cation
Size decreases because it
Loses electrons and more protons pull electrons harder
Atom to anion
Size increases bc gains electrons and less protons so weaker pull
Period left to right in terms of atom size
Size decreases because pull towards nucleus increases
Size of atoms group top to bottom
Size increases because N is related to size
Effective nuclear charger (Zeff) period left to right
Increases (#P-#core electrons)
Effective nuclear charge (Zeff) group too to bottom
Stays the same
Number of core electrons
Atomic number of noble gas before element
Zeff
Never negative
Always less than Z
Trends on periodic table
Effective nuclear charge (Zeff) Size of atoms/ions Ionization energy (Ez)
Valence electron attraction
Only attracted to a portion of the total net nuclear charge
Isoelectronic Set
Cations, anions, neutral all with same electron configuration
What is shield build from between inside protons and outside valence electron
Build from core electrons block full nuclear charge from pulling on valence electrons
