electron structure and orbitals

Question 1

what is an orbital?

Answer 1

• a region around the nucleus that can hold up to two electrons with opposite spins

Question 2

what is a sub-shell?

Answer 2

• within a shell, orbitals of the same type are grouped together as sub shells
• A subshell is a subdivision of electron shells separated by electron orbitals. Subshells are labelled s, p, d, and f in an electron configuration.

Question 3

define a mole.

Answer 3

• the amount of substance which contains as many particles as there are carbon atoms in 12g of carbon-12

Question 4

how are orbitals filled?

Answer 4

• they are filled in order of increasing energy

- the 4s sub shell is at a lower energy than the 3d sub shell so it is filled first

Question 5

Why must the electrons in an orbital have opposite spin and how is this shown?

Answer 5

• this is showing by arrows, one facing up and the other facing down
• they must have opposite spins to counteract the repulsion

Question 6

do the orbitals have the same energy within the same sub shell?

Answer 6

yes

- for example all p orbitals in the second shell will have the same energy

Question 7

how do the electrons fill the orbitals within the same sub shell?

Answer 7

• as they have the same energy, electrons first fill the orbitals unpaired to minimise repulsion
• they then pair with each other when there are no more orbitals in that sub shell left

Question 8

what is special about the elements in the s block of the periodic table?

Answer 8

• their outer electrons are in the s orbital

- their highest energy electrons are in the s sub shell

Question 9

How do electrons fill and empty regarding the 3d sub shell and 4s sub shell?

Answer 9

• 4s sub shell fills before 3d sub shell but also empties before
• because their energy levels are quite close together and when they fill the 4s sub shell is at a higher energy level than the 3d sub shell