Week 3

Question 1

The fundamental of an electron is…

Answer 1

determined Electrostatic attraction to nucleus, because it confines the wave to the nucleus

Question 2

Fundamental energy

Answer 2

The lowest energy level for any standing wave

Question 3

electron density is given by…

Answer 3

the square of a wavefunction

Question 4

1s orbital has

Answer 4

no node, lowest energy

Question 5

2s orbital has

Answer 5

1 spherical node,

Question 6

3s orbital has

Answer 6

2 spherical nodes

Question 7

Principle quantum number, n

Answer 7

determines the energy (size or shell) of the electron wavefunction.

nodes = n-1

Question 8

2p orbital has

Answer 8

1 planar node

Question 9

3p orbital has

Answer 9

2 nodes: 1 planar and 1 spherical

Question 10

3d orbital has

Answer 10

2 planar nodes

Question 11

magnetic quantum numbers for 2p and 3p

Answer 11

-1, 0, 1

Question 12

magnetic quantum numbers for 3d

Answer 12

-2, -1, 0, 1, 2

Question 13

More linear nodes leads to

Answer 13

shorter wavelength, and thus higher angular momentum

Question 14

Angular momentum quantum number, l

Answer 14

may take on any value between 0 and n-1

determines the shape (or subshell) and the # of planar nodes

Question 15

ml

Answer 15

determines orientation,
There is one s orbital, three p orbitals, five d orbitals in any one set.

Question 16

spin quantum number ms

Answer 16

Describes the “spin” of the electron

Question 17

The Pauli Exclusion Principle

Answer 17

no two electrons in an atom may be in the same quantum state
so,
no two electrons can have the same four quantum numbers, n, l,ml, and ms

Question 18

The Aufbau Principle

Answer 18

electrons in atoms (and molecules) generally exist in their lowest possible energy state - ground state

Electrons generally adopt the lowest possible energy configuration

Question 19

For multi-electron systems, n is no longer sufficient to predict energy levels. We now need to consider:

Answer 19

Electron-electron repulsion

Orbital Shielding

Question 20

Electron-electron repulsion

Answer 20

When we have more than one electron, the electrons within an orbital repel each other.

Question 21

Orbital Shielding

Answer 21

When an orbital is occupied, it shields the interaction of the outer orbital with the nucleus. This alters the energy levels of the orbitals

Question 22

For orbitals of equal n, those nearest the nucleus have…

Answer 22

the lowest energy

Question 23

Hund’s rule

Answer 23

The lowest energy electron configuration in orbitals of equal energy is the one with the maximum number of unpaired electrons with parallel spins

Question 24

Valence electrons

Answer 24

important in the formation of chemical bonds. They will lie in the same group in the periodic table, and form compounds with the same stoichiometry.

Noble gases are unreactive because they contain filled electron shells.

Question 25

Effective nuclear charge (Zeff)

Answer 25

positive charge felt by an electron in a multi-electron atom

Electrons in the outer orbitals are partially shielded from the nuclear charge resulting in a weaker attraction and a lower Zeff

Question 26

Atomic radii

Answer 26

Across a period, Zeff increases
* smaller radius
* high ionisation energy

Down a group, electrons are added to orbitals that are further from the nucleus
* larger radius
* low ionisation energy

Question 27

Anionic radii

Answer 27

When forming an anion, electrons are usually added to the same orbital:
Z is unchanged
Zeff is unchanged
More electrons > more electron repulsion

Question 28

Cationic Radii

Answer 28

When forming a cation, electrons are removed from the outer orbital
Now the valence orbital is closer to the nucleus > cation is smaller than atom

Question 29

Ionisation energy (Ei)

Answer 29

the amount of energy required to remove an electron completely from an atom.

Ionisation requires input of energy, so ionisation energy will always be positive.

Question 30

Larger Zeff means electrons…

Answer 30

are held more tightly to nucleus thus are harder to remove

higher ionisation energy

Question 31

Electron affinity (Eea)

Answer 31

The energy change when an electron is added to an atom in the gas phase.

If energy is released ➟ atom has an affinity for electrons, and it has a negative electron affinity

Question 32

Metals Vs. Non-metals (electrons)

Answer 32

Non metals: Elements have an affinity for electrons (readily gain electrons)

Metals: Elements have a very low ionisation energy (readily lose electrons)