Electronic configuration

Question 1

what is electronic config?

Answer 1

arranging electrons in an atom into orbitals

Question 2

Aufbau principle

Answer 2

build up from the bottom

Question 3

pauli exclusion principle

Answer 3

each orbital holds a max of two electrons with opposite spins

Question 4

Hund’s rule

Answer 4

every orbital in a sub shell gets one electron before any orbital gets two and the single electrons have parallel spin

Question 5

exceptions to electron config

Answer 5

4s sub shell has lower energy than 3d and usually fills first but not for some atoms such as chromium and copper - half filled or completely filled shells are more stable
- 4th row transition metals lose 4s before 3d

Question 6

periodicity or patterns on the periodic table

Answer 6

each row represents the number in front of the shell eg. 1s is row 1
each column represents a letter
s - 1 and 2
p - 13-18
d - 3-12
f- lanthanoid and actinoid

Question 7

condensed electron configs

Answer 7

use a noble gas

Question 8

Zeff

Answer 8

• effective nuclear charge (net charge of nucleus after considering attraction and repulsion of electrons)
• left to right: protons increase but number of shells is constant; Jeff increases
• top to bottom: protons and shells increase; Jeff decreases

Question 9

atomic radii

Answer 9

• size of the entire atom, including electrons
• number of shells - atomic radius generally increases top to bottom
• zeff in a row - atomic radius generally decreases left to right

Question 10

ionisation energy

Answer 10

• amount of energy required to remove one mol of electrons from one mol of gaseous atoms. energy is always positive - takes a lot
• as atomic radii decreases, more energy is required
• generally decreases down a group (outer electrons are further from the nucleus)
• generally increases across a period (Zeff increases)

Question 11

low ionisation energy from

high ionisation energy from

Answer 11

cations; anions

Question 12

successive ionisation energy

Answer 12

energy required to remove electrons after the first dramatically increases

Question 13

electron affinity

Answer 13

the amount of energy required to add 1 mol of electrons to 1 mol of gaseous atoms - positive or negative (subsequent values are always positive)

• increases bottom to top and left to right
• lower electron affinity tend to form cations and the opposite tend to form anions

Question 14

ground state

Answer 14

lowest energy for a set of electrons

Question 15

excited state

Answer 15

when one electron is at a higher energy level than its ground state - energy required

Question 16

degenerate

Answer 16

set of orbitals with the same energy such as 2px, 2py, 2pz

Question 17

ion size

Answer 17

cation - smaller than neutral

anion - larger than neutral