Electron arrangement and ionisation energies

Question 1

Defnintion of an element

Answer 1

A substance containing only 1 type of atom.

Question 2

Definition of an atom

Answer 2

The samllest particle with all the chemical properties of an element.

Question 3

Definition of an isotope

Answer 3

Atoms of the same element with different numbers of neutrons.

Question 4

Definition of relative isotopic mass

Answer 4

The mass of an atom of an isotope comapred with 1/12th of the mass of an atom of carbon-12.

Question 5

Definition of relative atomic mass

Answer 5

The average mass of an atom of an element compared with 1/12th of the mass of an atom of carbon-12.

Question 6

Calculating relative atomic mass

Answer 6

Realtive atomic mass = (isotope abundance x isotope mass) + … / (sum of all isoptope abundances)

Question 7

Method for determination of relative atomic mass

Answer 7

1. A sample is placed in the mass spectometer.
2. The sample is vaporised and then ionised to form positive ions.
3. The ions are accelerated. Heavier ions move more slowly and are more difficult to deflect than the lighter ones, so the ions of each isotope are separated.
4. The ions are detected on a mass spectrum as a mass-to-mass charge ratio m/z. Each ion reaching the detector adds to the signal, so the greater the abundance, the larger the signal.

Question 8

Mass-to-mass ratio (m/z) =

Answer 8

relative mass of ion / relative charge on ion

Question 9

Definition of a shell

Answer 9

A shell is a group of atomic orbitals in the same energy level.

Question 10

Defintion of a sub-shell

Answer 10

A group of the same type of atomic orbitals within a shell.

Question 11

Defintion of an atomic orbital

Answer 11

A region around the nucleus that can hold up to two electrons with opposite spins.

Question 12

Description of s-orbital shape

Answer 12

Spherical

Question 13

Description of p-orbital shape

Answer 13

Dumb-bell shape

Question 14

Shell 1

Answer 14

Shell number- 1
Sub-shells present- S
Number of electrons in each sub-shell- 2
Total number of electrons in entire shell- 2

Question 15

Shell 2

Answer 15

Shell number- 2
Sub-shells present- S and P
Number of electrons in each sub-shell- 2 (S) and 6 (P)
Total number of electrons in entire shell- 8

Question 16

Shell 3

Answer 16

Shell number- 3
Sub-shells present- S, P and D
Number of electrons in each sub-shell- 2 (S), 6 (P) and 10 (D)
Total number of electrons in entire shell- 18

Question 17

Shell 4

Answer 17

Shell number- 4
Sub-shells present- S, P, D and F
Number of electrons in each sub-shell- 2 (S), 6 (P), 10 (D) and 14 (F)
Total number of electrons- 32

Question 18

Electronic configuration rule for transition metals

Answer 18

When transition metals form ions, they lose electrons from the 4s before the 3d sub-shell.

Question 19

Definition of first ionisation energies

Answer 19

The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions.

Question 20

First ionisation energy equ for Li

Answer 20

Li (g) –> Li (g) + e-

Question 21

Trend in first ionisation energies across a period

Answer 21

• General increase in first ionisation energies across the period.
• There are more protons in the nucleus (greater nuclear charge).
• The outer electron is in the same shell- no increase in shielding.
• An increase in nuclear attraction for the outer electron.
• Atom radii decreases, so the outer electron is closer to the nucleus.
• More energy is required to remove the outermost electron.

Question 22

Trend in first ionisation energies fown a group

Answer 22

• The first ionisation energy decreases.
• More electron shells, so the outer electron is further from the nueclus.
• More electron sheilding (where inner electron shells repel outer shell electrons).
• Decreased nuclear attraction on outer shell.
• The number of protons increases but this is far outweighed by the increased shielding.
• Less energy required to remove outermost electron (the outer electrons are held less tightly).

Question 23

Definition of successive ionisation energies

Answer 23

A measure of the energy required to remove each electron in turn from an atom.

Question 24

Process of successive ionisation energies

Answer 24

Electrons are removed from the same atom starting from the outer electron and working in. The data is used to identify the atom.

Question 25

Successive ionisation energies increase due to…

Answer 25

1. The numberof protons remaining the same but proton to electron ratio is increasing.
2. There’s more nuclear attraction on remaining electrons.