P - Atomic Structure

Question 1

Electron configuration of Cr (Chromium)

Answer 1

1s²2s²2p⁶3s²3p⁶4s¹3d⁵ –> 6 unpaired e- –> more stable

Question 2

Electron configuration of Cu

Answer 2

1s²2s²2p⁶3s²3p⁶4s¹3d¹⁰

Question 3

Aufbau Principle

Answer 3

e- enter the lowest energy orbital possible.

Question 4

Hund’s Rule

Answer 4

e- only pair up when no empty orbitals of the same energy are available.

Question 5

Symbols of mass number and atomic number

Answer 5

Mass number (A) and atomic number (Z)

Question 6

First ionisation energy

Answer 6

The energy required to remove 1 mole of electrons from 1 mole of atoms in the gaseous state.

Question 7

Second ionisation energy

Answer 7

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

Question 8

Electron impact ionisation

Answer 8

Vaporised atoms are passed into a vacuum chamber,
where high energy electrons are fired at them,
knocking 1 electron from each of them to form a 1+ ion.

Question 9

Electrospray ionisation

Answer 9

High molecular mass compounds are dissolved in water or a volatile solvent,
injected through a positively charged needle at high voltage,
the spray emerging with the solvent losing an electron to form a positive ion.

Question 10

Isotopic abundances

Answer 10

The relative proportions of the stable isotopes of each element.

Question 11

Give an example (formula) for first ionisation energy.

Answer 11

Na(𝗴) –> Na+ (𝗴) + e-
ENDOTHERMIC

Question 12

Considerations for IE**

Answer 12

1. size of nuclear charge
2. distance of e- from nucleus
3. shielding (by inner e- & nucleus)

Question 13

Why is second IE higher than first IE?

Answer 13

First IE- removing e- from 𝙣𝙚𝙪𝙩𝙧𝙖𝙡 atom
Second IE- removing from 1+ 𝙞𝙤𝙣
𝙞𝙢𝙗𝙖𝙡𝙖𝙣𝙘𝙚: 𝙥𝙧𝙤𝙩𝙤𝙣𝙨 > 𝙚-
(∵ removed e-)

Question 14

Describe the trend for first IE across the PERIOD.

Answer 14

Increases, as:
1. ↑ protons in nucleus
∵ ↑ nuclear charge
2. Atoms get smaller-
∵ ↑ force of attraction betw. nucleus & outer e-

(2 up –> 1 down)
Eg. Period 3
1. Al < Mg
∵ outer e- in 3p- 1. ↑ energy 2. further from nucleus
∴ ↓ energy to remove

2. S < P
   ∵ 3p⁴ has 2 PAIRED e- ∴ repulsion- ↓ attraction to nucleus- ↓ energy to remove 1 from the pair than unpaired -easier =)

> increased shielding- negligible
∴ each successive e- enters same shell

Question 15

Describe the trend for first IE down the GROUP.

Answer 15

1. ↑ shielding
2. ↑ distance from nucleus
   ∴ weaker attraction from nucleus to outer e-

Question 16

How to determine what group the element it’s in from its successive ionisation energies?

Answer 16

Look for big jumps (eg. big jump from 2nd to 3rd –> group 2)
No apparent jump- group 0

Question 17

Why is it necessary to ionise atoms before acceleration?

Answer 17

Particles have to be charged before attraction to a charged plate/ electric field.

Question 18

What deflects ions in a mass spectromter?

Answer 18

Magnetic field.

Question 19

What is adjusted in order to direct ions with different m/z ratio onto the detector?

Answer 19

Magnetic field (/ strength of magnet)

Question 20

What accelerates positive ions before they are deflected?

Answer 20

Electric field.

Question 21

What factor, other than the mass to charge ratio of an ionised particle, determines how
much that particle is deflected in a magnetic field of a given strength?

Answer 21

Speed.

Question 22

Relative isotopic mass

Answer 22

Mass of the ISOTOPE relative to 1/12th the mass of an atom of Carbon-12.

Question 23

Isotopes of Cl

Answer 23

Cl-35 : Cl-37 = 3:1
m/z: 70 72 74
9 : 6 : 1

Question 24

What is the purpose of a detector in a mass spectrometer?

Answer 24

To detect POSITIVE IONS.

Question 25

Why do ions separate into different paths in a M. S.?

Answer 25

Diff. isotopes.

Question 26

For each type of ion, what 2 measurements can be made from the mass spectrum?

Answer 26

1. m/z
2. Abundance

Question 27

Formula of a ion
eg. C3H5O2N

Answer 27

C3H₆O2N+/ C3H5O2N𝑯+

Question 28

Write an equation for the electrospray ionisation of element X.

Answer 28

X (g) + H+ (g) –> XH+ (g)

Question 29

Write an equation for the electron impact ionisation of element X.

Answer 29

X(g) + e- –> X+(g) + 2e-

Question 30

How are particles accelerated in a mass spectrometer?

Answer 30

attracted to a -ve charged plate

Question 31

How many decimal places are included on low res mass spectrometry?

Answer 31

1

Question 32

How does high-res mass spectrometry allow us to identify compounds?

Answer 32

• measured to 5 d.p.
• see small diff. that low res x pick up

Question 33

When building a half equation, what is the first thing you balance?

Answer 33

species w/ variable oxidation state.

Question 34

After combining half equations, what should you remove?

Answer 34

spectator ions