Module 2.2.1 - Electron structure

Question 1

What is an atomic orbital?

Answer 1

The region within an atom around the nucleus that can hold up to two electrons with opposite spins

Question 2

What are shells/electronic energy levels?

Answer 2

A group of atomic orbitals with the same principal quantum number (shell number).
Shell closest to the nucleus , principal quantum number 1, has the lowest energy

Question 3

What is the maximum number of electrons the first 4 shells can hold?

Answer 3

Shell 1: 2
Shell 2: 8
Shell 3: 18
Shell 4 : 32

Question 4

What are sub-shells?

Answer 4

Within a shell, electrons are arranged into sub-shells, which are groups of the same type of atomic orbital within a shell.

Question 5

What are the 4 smallest sub-shells?

Answer 5

Made up of one type of atomic orbital only
s,p,d,f

Question 6

What shape does an s orbital have?

Answer 6

spherical

Question 7

What shape does a p orbital have?

Answer 7

A dumbbell/hourglass shape

Question 8

How many orbitals does each sub-shell contain? (and how many electrons maximum in each sub-shell?)

Answer 8

s sub-shell: 1(2)
p sub-shell: 3 (6)
d sub-shell: 5 (10)
f sub-shell: 7 (14)

Question 9

Which sub-shells are in the first shell and how many electrons can it hold?

Answer 9

s sub-shell only, can hold up to 2 electrons

Question 10

What sub-shells are in the 2nd shell and how many electrons can it hold?

Answer 10

s sub-shell and p sub-shell, can hold up to 8 electrons

Question 11

What sub-shells are in the 3rd sub-shell and how many electrons can it hold?

Answer 11

s, p,d sub-shells, can hold up to 18 electrons

Question 12

What sub-shells are in the 4th shell and how many electrons can it hold?

Answer 12

s,p,d,f sub-shells, can hold up to 32 electrons

Question 13

What is the order of increasing energy in sub-shells?

Answer 13

s,p,d,f (s has the lowest energy)

Question 14

How do electrons fill orbitals?

Answer 14

Start from lowest energy sub-shell first, closest to nucleus

Question 15

Why are 4s and 3d an anomaly?

Answer 15

4s fills its orbital up before orbitals in 3d sub-shell because 4s has a lower energy than 3d sub-shell.

Question 16

What are blocks of elements?

Answer 16

Blocks in the periodic table where elements have their highest energy electron in either s/p/d/f orbitals, making the elements s/p/d/f -block elements

Question 17

What are the electronic configurations of Cr and Cu? (from 3p^6)

Answer 17

Cr: 4s^1 3d^5
Cu: 4^1 3d^10

Only elements that have half-full 4s sub-shells (atoms more stable)

Question 18

What are transition elements?

Answer 18

D-block elements that forms an ion with an incomplete d sub-shell.
Lose their 4s electrons first when forming positive ions