Exam 1: Atoms and Molecules Flashcards
Development of Atomic Theory
Who discovered the electron?
JJ Tompson
Development of Atomic Theory
How was the electron discovered?
What expirement?
Cathode Ray Expirement
Particles deflected based on charge
Development of Atomic Theory
JJ Thompsons model of the atom
Plum Pudding Model
Negative electrons, surrounded by positivity
Development of Atomic Theory
Who discovered the nucleus? With what expirement?
Ernest Rutherford, Gold Foil Expirement
Alpha Particles pass through gold foil and bounce of nucleus
Development of Atomic Theory
What atomic model came of the Gold Foil Expirement?
Rutherford Model
Quantum Mechanics
Quantum Mechanics explains…
behaviour of microscopic matter
Classical Mechanics
According to Classical Mechanics is light a particle or a wave?
CLASSICAL MECHANICS
Wave
Classical Mechanics
F= (Q1)(Q2)/(4)(π)(ε)(r²)
Coulomb’s Force Law is used for…
Q= charge of particles
ε = permivitity constant
r = distances between pa
Force between 2 charged particles
Classical Mechanics
F=(m)(a)
Newton’s Second Law states…
F= force applied to particle
m= mass of particle
a= acceleration of particle
how fast particles are moving
Classical Mechanics
Classical Mechanics fails because…
it does not explain microscopic particle behaviour.
Quantum Mechanics
What two assumptions are made in Quantum Mechanics
- Radiation and matter display wave-like and particle-like properties (wave-particle duality)
- Energy is quanticed into discrete packets (photons)
Quantum Mechanics - Wave-Particle Duality
λ
Lambda
Wavelength: Distance between two successive maxima (or minima)
Quantum Mechanics - Wave-Particle Duality
μ
Mu
Frequency: Number of cycles per unit time
Unit Conversions
m to nm
m x 10^-9
Unit Conversions
nm to m
nm/10^-9
Light as a Wave
Causes periodic variation of ____ and ____ field
Electric and Magnetic
Light as a Wave
Emits ____ radiation
Electromagnetic
Light as a Wave
c = λμ
c = constant for electromagnetic waves
c = speed of wave (light) (m/s)
λ = wavelength (m)
μ = frequency (s^-1)
c = 2.9979 x 10^8 m/s
Colour of Light
Red has a ____ wavelength?
High
Colour of Light
Purple has a ____ wavelength?
Low
Colour of Light
Red has a ____ frequency
Low
Colour of Light
Purple has a ____ frequency
High
Wave Interaction
Define superposition
The result when two or more waves interact
Wave Interaction
Constructive interference is____
When two waves meet and there absolute amplitudes increase
Max + Max or Min + Min
Wave Interactiopn
Destructive Interference is ____
When two waves meet and their amplitudes cancel out
Max + Min
Wave Interference
At superposition wavelength and frequency of the waves change
True or False
False
Wavelength and frequency of the wave(s) does not change
Wave Interaction
Thomas ____’s ____ expirement proved ____
Name, Expirement Name, Expirement Purpose
Young, Double Slit Expirement, Light has wave properties
Photoelectric Effect
Electrons ejected if:
1. Frequency of light is less than the metal’s threshold frequency
2. Metal’s threshold frequency is less than the frequency of light
Choose 1 or 2
2
Photoelectric Effect
Number of electrons ejected increases as frequncy increase after the threshold frequency
True or False
False
After the threshold frequency the number of electrons is constant
Photoelectric Effect
Kinetic Energy (KE) of ejected electrons stays constant as frequency increase after the threshold frequency.
True or False
False
KE increases as frequency increases
Photoelectric Effect
Light intensity (photons/second) has no affect on Kinetic Energy
True or False
True
Photoelectric Effect
Number of electrons ejected increases as light intensity increases
True or False
True
Kinetic Energy Equation
KE = Ei - Φ
KE = Kinetic Energy
Ei = hµ = hc/λ = Energy of incident light
Φ = hµ (threshold frequency) = workfunction
New Photoelectric Effect
If KE is _ than zero there are no electrons ejected
Fill in the Blank
≤
Less than
New Photoelectric Effect
Number of electrons ejected is always less than the number of photons applied.
True or False
False
Number of electrons out = Number of photons in
Unit Conversion
eV to J
How to convert?
x (1.6022 x 10^-19)
Number on Equation Package
Unit Conversion
J to eV
J / (1.6022 x 10^-19)
Number on Equation Package
Photon Momentum
DeBroglie Wavelength Equation
Can be determined by equations on Equation Package
λ = h/mv
Schrodinger Equation
GP Thomson discovered light’s ….
He is also the son of …
Wave-like properties
JJ Thomson
Schrodinger Equation (Hydrogen)
The gorund state is the ____ energy level and it is the ____ stable state
Fill in the blanks
Lowest, most
Schrodinger Equation
En = -RH/n^2
This is the equation for binding energy of all atoms
Define variables and answer True or False
En = binding energy
RH = Rydberg’s Constant (on Equation Package)
n = Principle Quantum Number
False
This is the equation for Hydrogen ONLY with one elecetron
Binding Energy
For any one electron systems binding energy is equal to
En = -(Z^2)(RH)/n^2
True or False then define Z
True
Z = atomic number
Binding Energy
Binding energy is always….
+ or -
Negative
Binding Energy
A free electron has a binding energy > zero
True or False
False
Free electrons have 0 binding energy
Binding Energy
Consider the binding energy equation…
1. As n increases binding energy gets more negative and therefore electron is strongy bound
2. As Z increases binding energy gets more negative and therefore electron is weakly bound
True or False for each
- False, as n increases binding energy gets less negative causing weakly bound electrons
- False, as Z increase binding energy gets more negative causing strongly bound electrons
Ionization Energy and Binding Energy
En = -IE
Define and explain both sides of the equation
En = Binding energy and is always negative
IE = Ionization energy and is always positive
Ionization Energy
Ionization energy is the ____ energy needed to ____ electron
Fill in the blanks
minimum, remove
Ionization Energy
Ionization energy is always > zero
True or False
True
IE is always positive
Photon Emission
Electron goes from ____ n state to ____ low n state
Fill in the blanks
high, low
High to Low
Photon Emission
Electromagnetic Radiation is…
Photon Emission
Photon Emission
∆E = Ei - Ef
Define Variables
∆E = Change in energy = energy of photon emitted
Ei = energy at initial n state
Ef = energy at final n state
Balmer Series
____ Balmer discovered that H atoms emit visable light in the year ____
Fill in the blanks
JJ, 1885
Photon Emission
Large ∆E means ____ µ and ____ λ
Fill in the blanks
high, low
Photon Emission
Low µ and high λ results from a ____ ∆E
Fill in the blank
Small
Photon Emission
µ = [(Z^2)(RH)/h] [(1/nf^2)-(1/ni^2)]
Define Variables
Z = atomic number
RH = Rydberg’s constant
h = Planck’s constant
nf = final n state
ni = initial n state
Photon Absorbtion
Photon absorbtion is the ____ of photon emission. It occurs when photon goes from ____ n state to ____ n state.
Fill in the blanks
opposite/reverse, low, high
Low to High
Photon Absorbtion
µ = [(Z^2)(RH)/h] [(1/ni^2)-(1/nf^2)]
Define Variables
Z = atomic number
RH = Rydberg’s constant
h = Planck’s constant
ni = initial n state
nf = final n state
Wavefunctions
Wavefunction Symbol
𝚿
Wavefunctions
Wavefunctions depend on which 3 quantum numbers?
n, l, ml
Wavefunction Shapes
Degenerate wavefunctions (orbitals) have the same ____ and therefore same ____
Fill in the blanks
n value, energy
Wavefunction Shapes
Number of degenerate orbitals (wavefunctions) equal…
n^2
Wavefunction Composition
𝚿 = radial wavefunction x angular wavefunction
Define terms
Radial Wavefunction: dependent on n and l
Angular Wavefunction: dependent on l and ml
Wavefunction Composition
s orbitals are ____ symetric so all s orbitals share the same value for ____ wavefunction
Fill in the blanks
spherically, angular
Wavefunction Composition
Wavefunctions of s orbitals are dependent on radial or angular wavefunction?
Explain why
Radial because it is independent of θ and Φ therefore angular wavefunction is consistant across all s orbitals (spherical symetry)
Wavefunction Composition
All p orbitals have l = ____, so their ____ wavefunctions are all the same
Fill in the blanks
1, radial
Wavefunction Composition
p orbitals’ wavefunctions depend on their angular or radial wavefunctions?
Explain why
Angular because all p orbitals share a radial wavefunction, and angular wavefunctions differ due to differing ml values
Nodes
Radial nodes occur when a radius causes 𝚿 = ?
0
Nodes
Angular nodes occur when ____ cause 𝚿 = 0
Fill in the blank
θ and Φ/ angles
Nodes
Number of radial nodes =
n - 1 - l
Nodes
Number of angular nodes =
l
Nodes
Total number of nodes =
n-1
Radial Probability Distribution (RPD)
RPD graphs plot…
Probability of finding an electron at a certain radius
Radial Probability Distribution
The highest point on a RPD (rpm) is …
The value of r (the radius) where there is most likely to be an electron
Radial Probability Distribution
Radial nodes occur when RPD function …
touches x-axis/ equals zero
Radial Probability Distribution
As n increases, rpm…
increases
Radial Probability Distribution
As l increaes, rpm…
decreases
Multi Electron Systems
When describing an orbital ____ quantum number(s) should be used
Fill in the blank with a number
3
Multi Electron Systems
When describing an electron ____ quantum number(s) should be used
Fill in the blank with a number
4
Multi Electron Systems
Aufbau’s Principle says:
Electrons fill orbitals in order of lowest energy state to highest energy state
Multi Electron Systems
Hund’s Rule states:
A single electron occupies each orbital in each energy state before doubling up, and all single electrons are spin up.
Multi Electron Systems
Pauli’s Exclusion Principle states:
No two electrons can have the same exact quantum numbers, so when electrons share an orbital one will be spin up and the other spin down (ms = +1/2 vs. ms = -1/2)
Multi Electron Systems
Binding energy depends on ____ and ____ quantum numbers
Fill in the blanks
n, l
Multi Electron Systems
Enl = -IEnl = -(Zeff^2)(RH)/n^2
Define variables
Enl = Binding energy of multi electron system
IEnl = Ionization energy of multi electron system
Zeff = Effective charge (from sheilding effect)
RH = Rynberg’s constant
n = Principle quantum number
Sheilding Effect
Zeff should always be between Z is there was ____ sheilding and Z is there was ____ sheilding
Fill in the blanks
no, complete
Reminder: Z = atomic number, sheilding effect changes charge
Electron Configurations
Which 2 elements have exceptions to Aufbau’s principle? Why?
Cr and Cu because half filled and fully filled d orbitals are favoured over s orbitals.
d orbital steals electron from s orbital
Electron Configurations
s orbitals contain ____ electrons, p orbitals contain ____ electrons, d orbitals contain ____ electrons, f orbitals contain ____ electrons
Fill in the blanks with numbers
2, 6, 10, 14
Periodic Trends
On the periodic table, n quantum number is represented by….
Details!!!!!
Period
Groups 3 - 12 see that n = period number -1
Periodic Trends
On the periodic table, groups ____ and ____ will have their valence electrons in s orbitals
Fill in the blanks with numbers
1 and 2
Periodic Trends
On the periodic table, groups ____ to ____ will have their valence electrons in p orbitals
Fill in the blanks with numbers
13 to 18
Periodic Trends
On the periodic table, groups ____ to ____ will have their valence electrons in d orbitals
Fill in the blanks with numbers
3 to 12
Periodic Trends
On the periodic table, which elements have their valance electrons in f orbitals?
Special elements (atomic numbers 57-71 and 89-103)
Quantum Numbers
n is the…
principle quantum number
Quantum Numbers
l =
n-1
Quantum Numbers
l = 0 results in which orbital
s
Quantum Numbers
l = 1 results in which orbital
p
Quantum Numbers
l = 2 results in which orbital
d
Quantum Numbers
l = 3 results in which orbital
f
Quantum Numbers
ml =
range from -l to +l
Quantum Numbers
ms =
+1/2 or -1/2
Ions Electron Configurations
Once a d orbital is filled
(when an atom becomes ionized) the electrons are removed from previous s orbital
True or False
True
Electron Configurations
Isoelectronic ions and atoms are…
ions and atoms that have the same electron configurations
Periodic Trends
Describe the trend of IE in terms of the periodic table
IE increase as you move up and right across the periodic table
Periodic Trends
Describe the trend of Electron Affinity (EA) in terms of the periodic table
EA increase as you move up and right across the periodic table
Periodic Trends
Describe the trend of Electronegativity (X) in terms of the periodic table
X increase as you move up and right across the periodic table
Periodic Trends
Describe the trend of Atomic Radius in terms of the periodic table
Ionic Radius?
Atomic Radius increase as you move down and left across the periodic table
Increases as you move down the periodic table
Periodic Trends
What are the exceptions to the IE periodic trend?
Half full/ full orbitals are more stable and therefore favoured, so they have higher than expected ionization energies
Periodic Trends
What are the exceptions to the EA periodic trend?
Noble Gases are stable and do not seak stability therefore they have very negative EA
Bonding
Chemical bonding is the arrangment of atoms that result in ____ ____ energy than the atoms have seperatley
more negative
Periodic Trends
What are the exceptions to the X periodic trend?
Noble Gases are stable and do not seak electrons therefore they have X = 0
Bonding
The complete transfer of electrons is which type of bonding?
Ionic, Covalent, Polar-Covalent
Ionic
Bonding
Ionic bonding results in a ∆X
≥1.7
Bonding
Covalent bonding is when an electron pair is ____ shared between two atoms
Fill in the blank
equally
Bonding
∆X ≤ 0.4 is a result of which type of bonding?
Ionic, Covalent, Polar-Covalent
Covalent
Bonding
An unqual sharing of an electron pair is what type of bonding?
Ionic, Covalent, Polar-Covalent
Polar-Covalent
Bonding
Polar-Covalnet bonds have ∆X =
0.4-1.7
Bonding
Dissociation Energy is…
The amount of energy required to break a chemical bond and seperate chemically bonded atoms
Lewis Structures
In step 1, when drawing Lewis Structures, which atom goes in the middle?
The atom with the lowest IE
Lewis Structures
In step 2, when drawing Lewis Structures, one should total the number of…
Valence electrons
Lewis Structures
In step 3, when drawing Lewis Structures, one should total…
The number of electrons in full valence shells
Lewis Structures
In step 3, when drawing Lewis Structures, one should total…
The number of electrons in full valence shells
Lewis Structures
In step 4, when drawing Lewis Structures, one should determine the number of bonding electrons by…
Subtracting valence electrons (step 2) from full valence electrons (step 3)
Lewis Structures
In step 5, when drawing Lewis Structures, one bond is made up of ____ bonding electrons
Fill in the blank with a number
2
Lewis Structures
In step 6, when drawing Lewis Structures, if there are bonding electrons remaining one should
include double/tripple bonds
Lewis Structures
In step 7, when drawing Lewis Structures, one should determine the number of loan pair electrons by…
Subtracting bonding electrons (step 4) from total valence electrons (step 3)
Formal Charge
Formal charge applies to ____ bonding only
Fill in the blank
Covalent
Formal Charge
FC =
V-L-B
V = valence electrons
L = loan pair electrons
B = number of bonds
Formal Charge
Formal Charge is the extent to which an atom has lost/gained an electron
True or False
True
Formal Charge
How does formal charge relate to the charge of the molecule?
Sum of FC of each atom = molecule charge
Formal Charge
Lewis structures with highest absolute FC are the most stable and therefore have the lowest energy
True or False
False
*lowest absolute FC
Formal Charge
Negative FC = most electrnegative = most stable = highest energy
True or False
False
*lowest energy
Resonance Structures
All molecules have resonance structures
True or False
False
Resonance Structures
Resonance structures have ____ atom arrangment and ____ bond arrangment
Fill in the blanks
same, different
Resonance Structures
FC is constant across resonance structures
True or False
True
Octet Rule Exceptions
When there is an odd number of valence electrons it is impossible for…
all atoms to have complete octets
Octet Rule Exceptions
A radical species is a result of…
An unpaired electron from an odd number of valence electrons
Octet Rule Exceptions
Which two elements will be octet difficent (have incomplete octets)
Al and B
Aluminium and Boron
Octet Rule Exceptions
Which elements are eligable for valence shell expansion (expanded octet)?
Central elements with n ≥ 3, and empty d orbitals
