1. 1
   A student learns about two forms of carbon: carbon-12, which has 6 protons and 6 neutrons, and carbon-14, which has 6 protons and 8 neutrons.

   (a)

   Carbon-12 and carbon-14 are both atoms of the element carbon, but carbon-14 has two more neutrons than carbon-12. What term describes atoms of the same element with different numbers of neutrons?

   [1 mark]

   • AIsotopes
   • BIsomers
   • CIons
   • DIsobars

   (b)

   Which feature must be identical between two isotopes of the same element?

   [1 mark]

   • AThe total number of protons and neutrons
   • BThe number of neutrons
   • CThe mass number
   • DThe number of protons

   (c)

   Explain why carbon-12 and carbon-14 are both classed as isotopes of carbon.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   An atom of sodium is represented in standard isotope notation, with its mass number written above and its atomic number written below, next to the chemical symbol Na. For this atom, the mass number is 23 and the atomic number is 11.

   (a)

   An atom of sodium is represented using standard notation with the mass number written above the atomic number, next to the symbol Na. What does the number written above the symbol represent?

   [1 mark]

   • AThe number of electrons only
   • BThe atomic number
   • CThe mass number
   • DThe number of neutrons only

   (b)

   What does the number written below the symbol in standard isotope notation represent?

   [1 mark]

   • AThe mass number
   • BThe atomic number
   • CThe number of neutrons
   • DThe overall charge of the atom

   (c)

   State the number of protons and the number of neutrons in this sodium atom, showing your working.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Element Y has an atomic number of 12 and exists as two isotopes, Y-24 and Y-26.

   (a)

   State the number of protons and neutrons in each isotope.

   [3 marks]

   (b)

   Explain why Y-24 and Y-26 are both isotopes of the same element, and explain why they would be expected to have identical chemical properties despite having different masses.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Hydrogen has three isotopes, sometimes called protium, deuterium and tritium, with mass numbers 1, 2 and 3 respectively, and an atomic number of 1 in each case.

   (a)

   Describe what is meant by the term 'isotope', and describe how standard isotope notation is used to represent each of these three isotopes of hydrogen.

   [6 marks]

   (b)

   Explain why protium, deuterium and tritium have identical chemical properties but different physical properties, such as mass.

   [6 marks]

   Total for question 4: 12 marks

End of questions