Topic 1 - Atomic Structure and the Periodic Table

Question 1

1 - What is the atomic number of an element?

Answer 1

Atomic number is the amount of protons in the nucleus of the atom of an element. (Can also be called proton number)

Question 2

1 - What is the mass number of atom?

Answer 2

The total number of protons and neutrons in the nucleus of an atom (as these each have a relative mass of 1 amu)

Question 3

1 - What is the unit for relative mass of subatomic particles?

Answer 3

amu - Atomic mass unit

Question 4

1 - What are the mass and charges of the three subatomic particles?

Answer 4

• Proton:
  
  • m - 1
  • z - 1⁺
• Neutron:
  
  • m - 1
  • z - 0
• Electron:
  
  • m - 1/1836
  • z - 1^-

Question 5

1 - What are isotopes?

Answer 5

Atoms of the same element with different mass numbers (caused by different numbers of nuetrons in the nucleus)

Question 6

1 - What do isotopes of the same element have in common with each other?`

Answer 6

• Number of protons
• Number of electrons
• Atomic number
• Chemical properties

Question 7

1 - What differences do isotopes of the same element have between each other?

Answer 7

• Numbers of neutrons
• Mass numbers
• Physical properties

Question 8

1 - What are the physical properties of an atom based off of?

Answer 8

The electron configuration

Question 9

1 - What is A_r?

Answer 9

A_r - Relative atomic mass is the average mass of an element relative to the mass of 1/12^th of a ¹²C atom

(Which is essentially average mass of atom ÷ 1)

Question 10

1 - What is the unit for A_r?

Answer 10

There is no unit

As it is calculated by dividing the average mass of the element (unit amu) by the mass of 1/12^th of ¹²C atom (also unit amu), the units cancel out leaving no unit

Question 11

1 - What occurs during a mass spectrometry?

Answer 11

• Gaseous sample is input
• Bombarded with electrons to ionise
• Mass analyser seperates ions by m/z ratio (due to electrical field)
• Ion detector gives electrical impules which are stored as digital signals

Question 12

1 - What does m/z mean?

Answer 12

m/z is the mass to charge ratio (in mass spectrometry)Typically during mass spectrometry the isotopes will only lose one electron gaining a 1⁺ charge. This results in m/z = m . However, sometimes, if more electrons are lost the charge can be different

Question 13

1 - What equation shows what happens in the mass spectrometry of element X

Answer 13

e^- + X_(g) → X_(g)⁺ +2e^-

Question 14

1 - How can data from a mass spectrometry be represented?

Answer 14

In a ‘stick diagram’ where the x axis is the m/z value and the y axis is relative abundance

Question 15

1 - How do you calculate relative atomic mass for a sample of isotopes of an atom from mass spectrometry data?

Answer 15

• Multiply each mass value by it’s relative abundance
• Total these values
• Divide by the total values of of relative abundace

e.g 35-Cl if has a relative abundace of 30 and 37-Cl had an abundace of 10 then you would do:

( (35 x 30) + (37 x 10) ) ÷ (30 + 10)