In the late 1800s physist JJ Thomson discovered the electron. He proposed the 'plum pudding' model of the atom whereby negatively-charged electrons were distributed evenly throughout a sphere of positive charge.

The figure below shows an atom of element Q using the ‘plum pudding’ model.

An atom of Q contains eight electrons.

State two differences between the ‘plum pudding’ model and the model of atomic structure used today.

Complete the missing values in the table to show the numbers of sub-atomic particles in an atom and an ion of magnesium.

Explain why different isotopes of magnesium have similar chemical properties.

Define the term isotope.

Define the term relative atomic mass.

Calculate the relative atomic mass of silicon using information in the table below.

Give your answer to two decimal places.

This question is about atomic structure.

Define the mass number of an atom.

The table below gives some isotopic information about an atom and an ion of nickel. 

Identify the missing values A-D.

A sample of nickel contains three isotopes, ⁵⁸Ni, ⁶⁰Ni and ⁶²Ni.

This sample has a relative atomic mass of 58.7

In this sample the ratio of abundance of isotopes ⁶⁰Ni and ⁶²Ni is 7:1

Calculate the percentage abundance of ⁵⁸Ni in this sample.

Give your answer to one decimal place.

The figure below is a model proposed by Rutherford to show the structure of an atom.

State two features of the current model that are not shown in the Rutherford model.

This question is about isotopes.

Most elements contain atoms of different isotopes.

State one similarity and one difference between the atomic structures of isotopes of the same element.

Mass spectrometry can be used to identify the isotopes of chlorine.

Part of the mass spectrum of chlorine is shown below.

Calculate the relative atomic mass of chlorine.

Give your answer to two decimal places.

Three molecular ion peaks, M⁺, are found in the mass spectrum of chlorine, Cl₂.

The three M⁺ peaks have m/z values of 70, 72 and 74 respectively.

Suggest why each M⁺ peak is observed. 

A sample of iron, which consists of three isotopes, has a relative atomic mass of 55.909. The isotopic information for two of the isotopes is shown in the table below. The data for one of the isotopes, ^mFe, is missing.

Use this data to calculate m, the mass number of ^mFe.

Time of flight mass spectrometry is used to analyse a sample of tin.

The sample is ionised by electron impact to form 1+ ions.

The mass spectrum of this sample of tin has four peaks.

Data from the spectrum is shown in the table below.

Calculate the relative atomic mass of tin in this sample.

Give your answer to one decimal place.

This question is about the isotopes of krypton.

A sample of krypton containing the isotopes ⁸²Kr, ⁸³Kr, ⁸⁴Kr and ⁸⁶Kr has a relative atomic mass of 83.8.

The sample contains 11.6% each of the ⁸²Kr and ⁸³Kr isotopes.

Calculate the percentage abundance of each of the other two isotopes.

Give your answers to one decimal place.

The mass spectrum of a sample of selenium is shown below.

Use this spectrum to calculate the relative atomic mass of this sample of selenium.

Give your answer to one decimal place.

Explain why the A_r value of selenium you have calculated differs slightly from the relative atomic mass given in the Periodic Table.