Atomic Structure and Isotopes

Question 1

State the subatomic particles, their symbol, charge and relative masses.

Answer 1

1. Proton - 1+, 1 (p+)
2. Neutron - 0, 1 (n)
3. Electron - 1-, 1/1886 (e-)

Question 2

Define relative atomic mass.

Answer 2

Weighted mean mass of an element relative to 1/12 of the mass of an atom of carbon-12.

Question 3

What 2 things are needed to calculate RAM?

Answer 3

1. abundance % of each isotope

2. relative isotopic mass of each isotope

Question 4

Define isotope.

Answer 4

Atom of the same element with the same number of protons and electrons, but a different number of neutrons.

Question 5

Define RIM.

Answer 5

Mass of isotope relative to 1/12 of the mass of an atom of carbon-12.

Question 6

Why are the chemical properties of isotopes the same?

Answer 6

1. Electron number = the same

2. Only electrons are involved in chem reactions

Question 7

Why are the physical properties of isotopes different? Which properties differ?

Answer 7

1. Diff neutron number = diff mass number
2. Mass number determines phys prop’s
3. Affects: mass, density, mp + bp

Question 8

What is the purpose of a mass spectrometer?

Answer 8

Produces a mass spectrum which shows:

1. abundance % of each isotope
2. number of isotopes

Question 9

Why does the H+ ion make substances acidic?

Answer 9

1. H+ ion = 1 proton

2. More protons in atom = more acidic

Question 10

How does a mass spectrometer work?

Answer 10

1. Sample put into spectrometer
2. Sample is vaporised then ionised
3. Ions accelerated then deflected by electromagnet
4. Degree of deflection depends on ion’s mass-charge ratio
5. Heavier ion = deflected less and vi ver
6. Ions detected - produces a mass spectrum on computer

Question 11

What is special about the ions in a mass spectrometer?

Answer 11

They are always positive