Chapter 2: Electronic Structure Of The Atom Flashcards
How is the periodic table arranged?
Based on similarities in chemical behaviour and atomic weight.
Bohr’s Theory
- Electrons orbit the nucleus in fixed energy levels known as principle quantum number (n).
- Orbits further from the nucleus exist at higher energy levels.
-When electrons return to a lower energy level, they emit energy in the form of light.
What does Schrödinger wave equation describe?
The properties of electrons in atoms via position, mass, total energy, and potential energy.
What is the particle-wave duality?
Established by De Broglie states quantum entities exhibit particle or wave properties according to the experimental circumstances.
De Broglie equation
λ = h/vm
λ: wavelength
h: Planck’s constant
v: velocity
m: mass
What is the solution of Schrödinger wave equation?
The wave function
Define wave function?
Mathematical function describing the behaviour of an electron it consists of a radial and angular component.
What is atomic orbital?
The region of space define by wave function.
Results of Schrödinger wave equation
- Behaviour of electrons in regions of space called orbitals, through solution of equation; wave function
- Find energy values associated with particular wave function.
- Quantization of energy levels
What 4 quantum number characterise atomic orbitals?
- Principle Quantum Number (n)
- Orbital Quantum Number (l)
- Magnetic Quantum Number (ml - l subscript)
- Spin Quantum Number (ms- s subscript)
Principle Quantum Number
Responsible for determining the overall energy of the atomic orbital.
- Positive integers (1,2,3)
Orbital Quantum Number
Determined the angular component and the shape of an orbital.
- 0, 1, 2, n-1
Magnetic Quantum Number
Determined the orientation of an orbital.
- -l ….. +l
Spin Quantum Number
Describes spins of the electrons in a given orbital.
- +/- 1/2
What does different “l” values represent?
Different shapes of orbitals; eg s, p, d, f
Define node
The point where the electron probability is zero.
Define Degenerate Orbitals
Orbitals that possess the same energy.
What is the angular component of orbitals associated with?
It is associated with geometry and orientation of the orbitals, and it changes its sign in nodal planes.
s Orbitals
l = 0, ml = 0 (singly degenerate, only 1 s atomic orbital)
p Orbital
l = 1, ml = -1, 0, +1 (triply degenerate, 3 p atomic orbitals)
d Orbital
l = 2, ml = -2, -1, 0, +1, +2 (five-fold degenerate, 5 d atomic orbitals)
f Orbital
l = 3, ml= -3, -2, -1, 0, +1, +2, +3 (seven-fold degenerate, 7 f atomic orbitals)
What is the radial component of orbitals associated with?
Radial component of a wave function is associated with size of the orbitals.
- Decays exponentially with distance from nucleus (increase in r).
- Changes in sings in nodes
Radial Distribution Function
4πr^2R(r)^2
What does the Radial Distribution Function determine?
Describes the probability of finding an electron at a given distance from the nucleus.
Define a node
A surface where the wave function is zero as it changes sign. Probability of finding electrons is zero.
Which orbital have no radial nodes?
The lowest energy orbital of each classification (1s, 2p, 3d & 4f) has not radial node.
Where is the p orbital’s nodal plane?
Through the nucleus
Aufbau principle
- Electrons are placed in the lowest energy orbitals first.
- Covers the continual addition of electrons with increasing quantum numbers.
Pauli Exclusion Principle
Requires each electron in an atom to have a unique set of quantum numbers.
Hund’s Rule Of Maximum Multiplicity
Requires electrons be placed in orbitals to give the maximum total spin possible.
Electrons will occupy degenerate energy levels singly first before pairing up.
Why does Hund’s rule work like it does?
2e- in the same orbital have higher energy then 2e- in different orbitals (spin-paring energy; electrostatic replusion).
How does electron shielding work?
Inner shell e- shield from the attractive forced of nucleus with outer shell e- .
Slates Rule
