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CHEMISTRY-FY > S1- L5-6: The Electronic Configuration of the Atom > Flashcards

S1- L5-6: The Electronic Configuration of the Atom Flashcards

1
Q

What is “Quantum theory”?

A
  • theoretical basis of modern physics

- ->explains nature AND behavior of matter + energy on atomic plus subatomic level

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2
Q

Quantum theory explains some observations classical mechanics cant. Outline the 3 in this lecture

A

1-Spectra of light emitted by atoms
-e-‘s in atom stable + stay in their orbitals
2-wave-particle duality

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3
Q

Explain the first and third observations in appropriate detail

A

1- quantisation of energy AND energy levels (put energy in numbers like 400KJ
3-light able to behave as if made up of photons with energy depending on frequency
–>amount of light can see OR example depends on amount of photons coming from source which determines energy of light

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4
Q

Outline the following important concepts of quantum theory:

1-Uncertainity principle
2- e-‘s described as waves by Schrodinger equation

A

1-can never know exact location PLUS velocity of subatomic particle at same time (as constantly moving)
2-a mathematical function which describes e-‘s properties in quantum number terms

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5
Q

Describe the “Hydrogen spectrum”

A
  • shows existence of energy levels within atoms
  • e-‘s in atom are in stable energy levels
  • absorption of photon of light lets e- jump to higher level
  • jumping to lower level emits photon of light
  • measuring energy of photon lets energy difference between levels to be determined
  • ->showed energy levels not equally spaced
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6
Q

Define “ionisation energy”

A

-measures amount of energy needed to remove e-‘s from atoms/ions

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7
Q

What is “first ionisation energy”?

A

-energy needed to remove 1 mole of e-‘s (to infinity) form 1 mole of gaseous atoms to form 1 mole of gaseous (+) ions

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8
Q

Write the first ionisation energies of the following two elements:

1-Na/ 2-Al

A

1- Na(g) –> Na+ + e-

1- Al(g) –> A+ + e-

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9
Q

What is the effect of the charges of the particles involved?

A
  • e-‘s (-) charged AND protons in nucleus (+) charged
  • ->will be attraction between them
  • ->must add energy to system to pull e-‘s away
  • ionisation energies are (+)
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10
Q

Briefly explain the effect of the pull of the nucleus on ionisation energy

A
  • greater pull of nucleus
  • ->harder to pull e- away from atom
  • ->higher nuclear charge has higher ionisation energy
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11
Q

What do first ionisation energy patterns across a period and successive I. Energies for an element prove?

A

-give evidence for e-‘s being in subshell AND shells

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12
Q

Define “electron affinity”

A

-amount of energy needed to add e-‘s to atoms/ions

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13
Q

Outline what “First e- affinity” is and give an example

A
  • energy needed to add 1 mole of e-‘s to 1 mole of gaseous atoms to form 1 mole of gaseous (-) ions
  • Cl(g) + e- –> Cl- (g)
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14
Q

What does first electron affinities indicate?

A
  • indicate energy released on electron addition

- ->more (-) electron affinity the more stable negative ion formed

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15
Q

Explain the trend in atomic size in the periodic table (figure 1)

A
  • Increases as go down group as e- in higher energy levels
  • decreases as go across- as e- in same shell BUt increasing nuclear charge
  • ->so stronger attraction/pull to nucleus
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16
Q

Outline and explain the trend in first ionisation energy as you move down a group (figure 1)

A
  • Decreases down group as outer e- weaker attraction to nuclear charge (shielding) as atom bigger
  • increases across as shielding stays same BUT nuclear charge increases
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17
Q

What happens to the first electron affinity as you move down and across a group? (figure 1)

A
  • becomes less negative as go down group
  • ->as e- further away (larger atom) so more shielding and less attraction
  • more negative as go across periodic table
  • ->because incoming e- has stronger attraction to nucleus
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18
Q

Which key factors must be considered when explaining periodic table trends?

A
  • nuclear charge (protons in nucleus)
  • e- shells
  • shielding–> effect between outer e-‘s AND nucleus
  • ionisation energy
  • electronegativity
  • atomic size
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19
Q

State the purpose of quantum numbers

A
  • identify various energy levels available with atom in which e- can reside
  • identification numbers addresses each e- in atom
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20
Q

What do identification numbers specifically address for each e-?

A
  • specifically position (location) of e- in atom
  • predict direction of spin/rotation of e-
  • determine energy AND angular momentum of e-
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21
Q

Outline the 4 quantum numbers and their symbols

A
  • Principal Quantum Numbers (n)
  • Azimuthal Subsidiary Quantum Numbers (l)
  • Magnetic Quantum Numbers (m)
  • Spin Quantum Numbers (s)
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22
Q

Describe what an “orbital” is

A
  • region where approx 95% probability of finding particular e-
  • ->can not specify exact location of e-
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23
Q

What is a “node”?

A

-place less likely to find e- in orbital

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24
Q

Explain what principal energy levels are

A
  • In ply-electron atoms-principal energy levels called shells
  • ->referred to by letters K/L/M
  • ->these correspond to principal quantum numbers n. of “n” (n= number greater than 0)
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25
What is the value of n for the different shells?
- K--> n= 1 - L--> n=2 - shells contain multiple orbitals except n=1
26
Outline what happens to energy levels as n increases in complex atoms
-where more than 1 e- energy levels get closer together as n increases
27
What does the Principal Quantum Numbers (n) indicate?
- distance of e- from nucleus: higher n is--> further away e- from nucleus - energy of e-: higher n-->higher e- so less tightly held so easier to remove - n. of e- shell able to hold: n can have 2n^2 e-'s
28
Hoe many e-'s do each the K/ L/ M/ N shell hold?
- K shell: n=1 holds max 2x1^2= 2 e-'s - L shell: n=2 holds 2x2^2= 8 e-'s - M shell: n=3 holds 2x3^2= 18 e-'s - N shell: n= 4 holds 2x4^2= 32 e-'s
29
What are subshells (L) and how are they described?
- group of orbitals with same energy called subshell | - subshells described by azimuthal OR subsidiary quantum number l
30
What is the value of (L) dependent on/determined by?
- value of "L" depends on value of n - ->L can have value from 0 to (n-1) - ->i.e: l=0/1/2/2...(n-2), (n-2) - ->these correspond to different subshells which designated letters s/p/d/f
31
Outline what the letters s/p/d/f stand for
-sharp/ principal/ diffuse/ fundamental
32
State what the Azimuthal Quantum Numbers (L) indicates | refer to figure 2
L indicates: - which subshell e- is in - energy of subshell increases with increasing L - orbital shape in that subshell - max n. of e-'s given subshell able to hold--> 2(2L+1)
33
What are the shapes of the s/p/d/f orbitals? (refer to figure 3)
- s- spherical - p- dumbbell - d- more complex - f- still more complex
34
Outline what n and l are used to identify (refer to figure 4)
- combination of n and l (nl) identify particular subshell | - ->so describe e- location in atomic energy levels
35
What are Magnetic Quantum Numbers (m) and their significance? (figure 5)
- represents orbitals in given sub-shell - indicates direction of particular orbital relative to magnetic field/axes - not indicate energy - "m" can have integral vale ranging from -l -->0 to +l - ->so for given l value total n. of m values is (2l +1)
36
Figure 6-shape and orientation of orbitals
-Analyse and be able recognise
37
Explain what Spin Quantum Numbers (S) are
- e- moving around nucleus rotates/spins about it's own axis clockwise OR anti-clockwise direction - ->directions described by spin quantum number - ->can have 2 values clockwise spinning of e- indicates (+1/2) AND anticlockwise (-1/2) - 2 e-'s in same orbital must have opposite spins (+1/2 AND -1/2) also described as anti-parallel spins
38
What is the significance of the clockwise and anti-clockwise spins? (refer to figure 7)
- spins also known as up and down spins | - the opposite spinning of e- produces opposite magnetic field
39
Quantum number's summary: 1-Principal 2-Azimuthal 3-Magnetic 4-spin Quantum number--> Restriction--> Range
1- n --> positive integer--> 1,2,3..... 2- l --> 0 AND positive integers less than n --> 0,1,2...(n-1) 3- m --> integers between -l and +l --> -l,..-1,0,+1,..+l 4- s --> +1/2 OR -1/2 --> +1/2 OR -1/2
40
What is the Heisenberg's Uncertainty Principle?
-Can not determine position AND momentum of e- at same time
41
Outline the Aufbau Principle
-e-'s enter lowest available energy level first
42
Describe Hund's Rule to Maximum Capacity
- when in orbitals of equal energy e-'s will try to remian unpaired - ->minimises repulsion between like charges so system more stable
43
What is the Pauli Exclusion Principle?
- no two e-'s able to have same 4 quantum numbers | - ->only two e-'s able to go in each orbital- providing they are of opposite spin
44
Briefly explain what Madelung's rule is
- energy of atomic orbitals increases as (n+1) increases | - ->for identical values of n+1 energy increases with increasing n
45
Analyse the figures of the max n. of e-'s in subshells AND the max n. of e-'s in energy levels
-Refer to figure 8 and figure 9
46
What happens to energy levels as you get further from the nucleus?
-the energy levels get closer together
47
Outline the order of filling orbitals up to 4f
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 4d, 4f
48
Order of filling orbitals
-analyse figure 10
49
Why do high values of n fill first before lower n values?
-due to interactions between multi-electron energy level atoms not equally being spaced out
50
Periodic table and electron configuration
-analyse figure 11
51
How would you write the electronic configuration of a Helium atom?
- He atomic number is 2 - ->start by filling 1s subshell- able to hold up to 2 e-'s - ->write n. of e-'s in each subshell as subscript - ->so e- configuration of He is 1s2
52
Outline the method to write the e- configuration of an N atom
- atomic number is 7 - ->start filling 1s subshell which able to hold up to 2e's - ->then 2s subshell (2 e-'s) then 2p (6 e-s) - ->SO N e- configuration: 1s2, 2s2, 2p3 - ->total n. of e-'s in all orbitals must add up to atomic number
53
How may the electron configuration of N be written in more detail?
-N--> 1s2, 2s2, 2p3 -there are 3 p orbitals (m= +1, 0, -1) in 2p sub-shell -Hund's rule--> when in orbitals of equal energy e-'s will try to remain unpaired -->so can write e- configuration in more detail: 1s2, 2s22px12py12pz1 -->or as diagram (figure 12)
54
What are the special cases in the e- configuration rules?
- Chromium- atomic number is 24 - ->1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d5 - Copper - ->1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d10
55
How are positive and negative ions formed?
- (+ cations): formed by removing e-'s from atoms | - (- anions): formed by adding e-'s to atoms
56
In what order must e-'s be removed in the formation of ions?
-e-'s first removed from highest occupied orbitals except transition metals
57
Outline the formation of Na and Cl ions
- Na: 1s2, 2s2, 2p6, 3s1 - -> remove 1 e- from 3s orbital to form Na+ (1s2, 2s2, 2p6) - Cl: 1s2, 2s2, 2p6, 3s2, 3p5 - ->add 1 e- to 3p orbital to form Cl- (1s2, 2s2, 2p6, 3s2, 3p6)
58
How are ions formed from transition metals?
-e-'s in 4s orbital removed before any e-'s in 3d orbital
59
Example: Titanium
-refer to figure 13
60
Figure 14 shows the successive ionisation energies of Calcium. What does a large jump in I. Energy indicate?
-large jump between successive I. Energy indicates change in energy level from which e- been removed
61
Analyse the trend in 1st variation of I. Energy across a period
-Figure 15- shows the trend
62
Why is GD3+ commonly used for MRI scanning image enhancement?
- GD3+ has 7 unpaired e-'s | - ->better image of structures inside body
63
Summary of lecture
- e-'s occupy shells around nucleus - ->each shell only able to carry set n. of e-'s - shells contain orbitals-->region of space where e- likely to be found - e's enter orbitals at lowest energy level first - orbitals filled in increasing energy order - orbitals AND their e-'s characterised by 4 parameters-Quantum Numbers - quantum numbers describe size/shape AND spatial orientation of e-'s probability distribution/density AND its spin - orbitals; shape AND filling rules - how to write e- configuration - ionisation energy/ trends in ionisation energy AND their explanations

CHEMISTRY-FY (11 decks)

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