2.1.1 Atomic Structue And Isotopes

Question 1

Definition of an isotope.

Answer 1

Atoms of the same element with different number of neutrons and different masses.

Question 2

What is the mass number?

Answer 2

Number of protons + number of neutrons.

Question 3

What is the atomic number?

Answer 3

Number of protons.

Question 4

Relative charge of protons, neutrons and electrons.

Answer 4

Proton: 1+
Neutron: 1
Electron: 1-

Question 5

Relative mass of protons, neutrons and electrons.

Answer 5

Proton: 1
Neutron: 1
Electron: 1/1836

Question 6

Where is most of an atom’s mass?

Answer 6

In the nucleus.

Question 7

Definition of relative isotopic mass.

Answer 7

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

Question 8

Definition of relative atomic mass.

Answer 8

Weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12.
(Weighted mean mass takes into account % abundance of each isotope and relative isotopic mass of each isotope)

Question 9

What do mass spectrometers show?

Answer 9

Percentage abundance of isotopes in a sample of an element.

Question 10

What is the y axis of mass spectra?

Answer 10

% abundance of ions.
(Relative isotopic abundance)

Question 11

What is the x axis of mass spectra?

Answer 11

M:Z (mass/charge).
(Relative isotopic mass)

Question 12

How to work out relative atomic mass from mass spectra?

Answer 12

Multiply each relative isotopic mass by its relative isotopic abundance and add them up.
Divide by sum of isotopic abundances.