3.1 Atomic structure

Question 1

Explain the existence of isotopes

Answer 1

-big bang nucleosynthesis
radioactive decay

Question 2

equation for electrospray ionisation

Answer 2

X (g) + H+ → XH+ (g)

Question 3

Equation for electron impact ionisation

Answer 3

X (g) → X+ (g) + e-

Question 4

what does the mass spectrometer give information about?

Answer 4

-relative isotopic mass
-relative abundance of isotopes

Question 5

what is electrospray ionization?

Answer 5

The sample is dissolved in a volatile solvent, sprayed through a high-voltage needle, and gains a proton

Question 6

What is electron impact ionization?

Answer 6

A high-energy electron knocks an electron from the sample, forming a positively charged molecular ion

Question 7

Acceleration?

Answer 7

The positively charged ions are accelerated by an electric field, ensuring they all have the same kinetic energy

Question 8

Flight tube?

Answer 8

The ions travel through a field-free region (flight tube), where their velocity depends on their mass-to-charge ratio (𝑚/𝑧)

Question 9

TOF principle?

Answer 9

Lighter ions move faster and reach the detector sooner, while heavier ions travel more slowly

Question 10

velocity equation?

Answer 10

Since all ions have the same kinetic energy, their velocity is given by
𝑣=√ (2𝐾𝐸= m)

Question 11

Time equation?

Answer 11

Time Equation – The time taken to reach the detector is
𝑡=𝑑/𝑣, where 𝑑 is the flight tube length

Question 12

how does detection happen?

Answer 12

Ions hit the detector, where their arrival generates an electrical signal

Question 13

how is ion abundance detected?

Answer 13

The size of the signal corresponds to the abundance of ions with a particular 𝑚/𝑧 value

Question 14

molecular ion peak?

Answer 14

The peak with the highest
𝑚/𝑧 value

Question 15

Is TOF high or low resolution?

Answer 15

HIGH-Some TOF instruments provide accurate mass measurements to several decimal places, distinguishing between similar compounds

Question 16

Define 1st I.E and give an equation

Answer 16

The first ionization energy is the energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous positive ions. The general equation is:
𝑋(𝑔)→𝑋+(𝑔)+𝑒−

Question 17

what factors affect IE?

Answer 17

-nuclear charge
-distance from nucleus
-shielding

Question 18

How does nuclear charge affect IE?

Answer 18

-more protons in nucleus
-more positively charged nucleus
-stronger attraction for the electrons

Question 19

How does distance from nucleus affect IE?

Answer 19

-attraction decreases with distance
-an electron close to the nucleus will be much more attracted than one further away

Question 20

How does shielding affect IE?

Answer 20

-as the no.electrons btwn outer e-s and nucleus increases, outer e-s feel less attraction

Question 21

which 2 elements have different electronic configurations?

Answer 21

chromium and copper

Question 22

electronic configuration of a cr atom

Answer 22

1s2,2s2,2p6,3s2,3p6,3d5,4s1

Question 23

electronic configuration of a Cu atom

Answer 23

s2,2s2,2p6,3s2,3p6,3d10,4s1

Question 24

why is second IE greater than the first

Answer 24

electron is being removed from +ve ion which will require more energy

Question 25

IE trend down group 2?

Answer 25

- DECREASES - provides evidence electron shells exist - due 2 shielding + nuclear attraction

Question 26

IE trend across period 3

Answer 26

- INCREASES - due 2 increasing no.potons