Subatomic particles and the nuclear atomIB MYP Chemistry: Subtopic test

1. 1
   A school technician is making a poster about the particles inside a carbon atom. The poster must show students the three types of subatomic particle, where each one is found in the atom, and how their masses and charges compare.

   (a)

   Which subatomic particle carries a negative charge?

   [1 mark]

   • AProton
   • BNeutron
   • CElectron
   • DNucleus

   (b)

   In which part of an atom are the protons and neutrons found?

   [1 mark]

   • AIn the nucleus
   • BIn the outer shells
   • CSpread evenly through the whole atom
   • DIn the space between the shells

   (c)

   Describe the relative mass and relative charge of a proton and of an electron.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   In 1911 a team of scientists fired a beam of positively charged alpha particles at a very thin sheet of gold foil and used a detector to record where the particles ended up. Before this, many scientists pictured the atom as a ball of positive charge with tiny electrons scattered through it. The team found that nearly all the alpha particles passed straight through the foil, a small number were deflected through large angles, and a very few bounced almost straight back.

   (a)

   The ball-of-positive-charge model with electrons scattered through it is known as which model?

   [1 mark]

   • AThe solid sphere model
   • BThe nuclear model
   • CThe shell model
   • DThe plum pudding model

   (b)

   Which observation could not be explained by the plum pudding model?

   [1 mark]

   • ANearly all particles passed straight through
   • BA very few particles bounced almost straight back
   • CThe detector recorded alpha particles
   • DThe foil was extremely thin

   (c)

   Explain why most alpha particles passed straight through the foil but a very few bounced back.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A science teacher is preparing a lesson on a lithium atom, which contains 3 protons, 4 neutrons and 3 electrons. She also wants to show how scientists' ideas about the atom changed between the early 1800s and the early 1900s. Students may use the fact that protons and neutrons have a relative mass of 1 and that an electron has a negligible relative mass.

   (a)

   Explain why a lithium atom has no overall charge and why almost all of its mass is in the nucleus.

   [3 marks]

   (b)

   Outline how the model of the atom developed from Dalton to Bohr.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A class models Rutherford's gold foil experiment. A cardboard shape is fixed to a table and hidden under a sheet of board so that students cannot see it. Students roll identical marbles from a ramp across the board and record where each marble comes out on the other side. From the paths of the marbles they try to work out the size and position of the hidden shape. The class also uses Bohr's shell model of the atom to explain chemical reactions in later lessons.

   (a)

   Design an investigation using the marble model to find out whether the size of the hidden shape affects the proportion of marbles that are deflected. Include a hypothesis with a reason, the variables and how you would make the results reliable.

   [6 marks]

   (b)

   Discuss and evaluate whether students should still be taught Bohr's shell model of the atom, even though scientists now use more advanced models.

   [6 marks]

   Total for question 4: 12 marks

End of questions