Lecture 5 + 6 - The Electronic Configuration of the Atom

Question 1

what is quantum theory?

Answer 1

the theoretical basis of modern physics that explains the nature and behaviour of matter and energy on the atomic and subatomic level

Question 2

what is wave-particle duality?

Answer 2

light can behave ad if made up of photons with energy depending on frequency

Question 3

what is the uncertainty principle?

Answer 3

you can never know both the exact location and velocity of a subatomic particle at the same time

Question 4

what is the hydrogen spectrum?

Answer 4

• electrons in an atom are in stable energy levels
• absorption of a photon of light allows an electron to jump up to a higher level
• jumping down to a lower level emits a photon of light
• measuring the energy of the photon allows the energy difference between levels to be determined - shows that energy levels are not equally spaced

Question 5

what is the first ionisation energy?

Answer 5

the energy required to remove one mole of electrons from one mole of gaseous atoms in their ground electron configuration to form one mole of gaseous positive atoms

Question 6

what is first electron affinity?

Answer 6

the energy required to add one mole of electrons to one mole of gaseous atoms in their ground state to form one mole of gaseous negative atoms

Question 7

what is the trend for atomic size across the periodic table?

Answer 7

increases down the group, decreases across the period

Question 8

what is the trend for first ionisation energy across the periodic table?

Answer 8

Decreases down the group, increases across the period

Question 9

what is the trend in first electron affinity across the periodic table?

Answer 9

• becomes less negative down the group

- becomes more negative across the period

Question 10

what are the four quantum numbers?

Answer 10

1. Principal (n)
2. Azimuthal (l)
3. Magnetic (m)
4. Spin (s)

Question 11

what is an orbital?

Answer 11

a region in space where there is a given 95%probability of finding a particular electron

Question 12

Describe principle energy levels

Answer 12

• Referred to by K,L,M
• They correspond to principal quantum number
• Known as shells and shells have multiple orbitals except n=1

Question 13

Describe principal quantum numbers (n)

Answer 13

• higher n, the further away the electron from the nucleus
• higher n, higher energy electrons, less tightly held so easier to remove
• n can hold 2n^2 electrons

Question 14

Describe azimuthal quantum numbers (l)

Answer 14

indicates which sub shell the electrons are in 
s- l=0
p- l=1
d- l=2 etc 
maximum number of electrons = 2(2l+1)

Question 15

what shape is l=0?

Answer 15

spherical

Question 16

what shape is l=1?

Answer 16

dumbbell

Question 17

what shape is l=2?

Answer 17

more complex

Question 18

what shape is l=3?

Answer 18

still more complex

Question 19

Describe Magnetic quantum numbers

Answer 19

• identifies the orientation of individual orbitals within a sub shell
• can have a value between -1 to +1 so total number of m value is (2l+1)

Question 20

Describe spin quantum numbers

Answer 20

• defines the rotation of an electron about its own axis
• it can have two values +1/2 or -1/2
• two electrons in the same orbital must have opposite spin

Question 21

what is the aufbau principle?

Answer 21

electrons enter the lowest available energy level first

Question 22

what is Hund’s rule of maximum multiplicity?

Answer 22

when in orbitals of equal energy electrons will try to remain unpaired, minimises repulsion in the system so it is more stable

Question 23

what is Heisenbergs uncertainty principle?

Answer 23

you cannot determine the position and momentum of an electron at the same time

Question 24

what is the Pauli exclusion principle?

Answer 24

no two electrons can have the same four quantum numbers, only two electrons can go in each orbital providing the are of opposite spin

Question 25

what are the two exceptions with electron configuration?

Answer 25

chromium and copper - they fill the 4s1 and then move to the 3d

Question 26

what is a common contrast agent for medical imaging?

Answer 26

gd3+ as it has 7 unpaired electrons