Atomic orbitals, electron configuration and the periodic table

Question 1

What is an orbital?

Answer 1

An orbital is an area of space where there is >90% chance of finding an electron.

Question 2

What do quantum numbers tell us?

Answer 2

Where to find an electron in an orbital

Question 3

What are the four steps of quantum numbers?

Answer 3

1. Principle quantum numbers
   2.angular momentum quantum numbers
   3.magnetic quantum numbers
   4.spin quantum numbers

Question 4

What are principle quantum numbers? (n)

Answer 4

Essentially how far away from the nucleus it is,
n=1 is the 1st shell
n=2 is the 2nd shell
n=3 is the 3rd shell etc

the further away from the nucleus the higher the value of n

Question 5

What are angular momentum quantum numbers? (l)

Answer 5

Essentially the shape
- each shell has up to 4 subshells
S block- l=0
P block l=1
D block l=2
F block l=3

Question 6

What is Heisenberg’s uncertainty principle?

Answer 6

It is not possible to define both the position and the momentum of an electron in the same instant.

Question 7

What does the shape of an s orbital look like ( l=0 )

Answer 7

all s orbitals are spherical in shape and the size depends on the value of n - you should be able to recognise these and draw them

Question 8

what does the shape of a p orbital look like ( l=1 )

Answer 8

They are not spherical in shape and look like infinity signs
all 3 p-orbitals are equal in energy
you should be able to recognise and draw these

Question 9

What does a d orbital look like

Answer 9

they are not spherical, usually consists of shapes that look like 2 infinity signs together.
all 5 d orbitals are normally degenerate

Question 10

What does degenerate mean?

Answer 10

Equal in energy

Question 11

What are magnetic quantum numbers?

Answer 11

Magnetic quantum numbers distinguish between the different suborbital within the Sprint,d and f subshells
magnetic quantum numbers have the values -l,…, 0,…, +l

Question 12

What are spin quantum numbers?

Answer 12

electrons have a spin rotation in additions top orbital rotation around the nucleus
Can either be +1/2 or -1/2

Question 13

What is the layout for writing quantum numbers?

Answer 13

( n, l, ml, ms )
n= energy level
l= shape
ml= type of suborbital
ms= spin +1/2 or -1/2

Question 14

What is the Pauli Exclusion Principle?

Answer 14

• no two electrons have the same 4 quantum numbers
  -an orbital can hold a maximum of 2 electrons

Question 15

What is the Aufbau principle?

Answer 15

orbitals with the lowest energy fill up first, the lowest energy orbitals are not always necessarily closest to the nucleus.

Question 16

In what order to orbitals fill up? (written out diagram)

Answer 16

Starting from the lowest energy orbitals

1s, 2s, 1p, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, 8s

Question 17

what is Hund’s rule?

Answer 17

Where electrons occupy degenerate orbitals, each electron will take a separate orbital until all the orbitals in that sub shell are half-filled.
( electrons fill in order to maximise the number of parallel spins - electrons do not pair until they have too. )

Question 18

How many electrons are in each orbital (s,p,d)

Answer 18

s=2
p=6
d=10

Question 19

How do you write box notation?

Answer 19

Draw one arrow pointing up wards and one pointing downwards for each electron on each orbital, do not pair the electrons in the orbital until you haver too.

Question 20

What is ionisation energy ( higher definition )

Answer 20

The energy required to remove one mole of electrons from one mole of atoms in the gaseous state

Question 21

What is the relationship between stability of electron configuration and ionisation energy.

Answer 21

The more stable the electron configuration, the higher the ionisation energy.

Question 22

Why is the second ionisation energy a lot greater then the first?

Answer 22

Because the second ionisation energy requires removing an electron from a shell closer to the nucleus, so there is a greater force of nuclear attraction ion acting on this shell as it is closer to the nucleus.

Question 23

What are 3 factors affecting ionisation energy?

Answer 23

Atomic size, Nuclear charge, Screening effect

Question 24

How does atomic size affect ionisation energy?

Answer 24

The greater the atomic radius of the atom, the further the distance of the outermost electrons , this lowers the ionisation energy as the electrons are less attracted to the nucleus the further away they are.

Question 25

How does nuclear charge affect ionisation energy?

Answer 25

The greater the number of protons the greater the attraction to the outer electrons and harder it is to remove electrons.
elements across a period have decreasing atomic size and increasing number of protons in the nucleus therefore increasing ionisation energy.

Question 26

How doe the screening effect affect the ionisation energy?

Answer 26

Inner electron shells shield the outer electron shells from the attractive forces from the nucleus.
this makes the outer electrons easier to remove so the ionisation energy decreases.

Question 27

Why does Beryllium have a higher 1st ionisation energy than the trend would expect.

Answer 27

electron configuration of Be - 1s^2 , 2s^2

removing an electron from Be will break a full subshell, this requires more energy so it increases the ionisation energy.

Question 28

Why Is the first ionisation energy of Boron a lot lower than expected?

Answer 28

Electron configuration of B - 1s^2, 2s^2, 2p^1

removing an electron from B empties the 2p sub shell and makes the 2s^2 sub shell the outer shell.
Creating a full outer shell is favoured and this is why the IE of B is a lot lower.

Question 29

Why does Nitrogen have a higher 1st ionisation energy than expected?

Answer 29

Electron configuration of N - 1s^2, 2s^2, 2p^3

removing an electron from N breaks a relatively stable half filled 2p sub shell, breaking half filled subshells requires more energy which is why the IE is higher.

Question 30

Why does Oxygen have lower 1st ionisation energy than expected?

Answer 30

Electron configuration of O - 1s^2, 2s^2, 2p^4

removing an electron from O creates a half-filled 2p sub shell which is more stable.
Creating a half-filled sub shell is favoured and this is why the ionisation energy is a lot lower.