DP Chemistry (first assessment 2025)

Question 21N.2.SL.TZ0.8

Date	November 2021	Marks available	[Maximum mark: 5]	Reference code	21N.2.SL.TZ0.8
Level	SL	Paper	2	Time zone	TZ0
Command term	Sketch, State, Suggest	Question number	8	Adapted from	N/A

[Maximum mark: 5]

21N.2.SL.TZ0.8

Fast moving helium nuclei (⁴He²⁺) were fired at a thin piece of gold foil with most passing undeflected but a few deviating largely from their path. The diagram illustrates this historic experiment.

Figure from PPLATO / FLAP (Flexible Learning Approach To Physics), http://www.met.reading.ac.uk/pplato2/h-flap/
phys8_1.html#top 1996 The Open University and The University of Reading.

(a)

Suggest what can be concluded about the gold atom from this experiment.

[2]

Markscheme

Most ⁴He²⁺ passing straight through:

most of the atom is empty space
OR
the space between nuclei is much larger than ⁴He²⁺ particles
OR
nucleus/centre is «very» small «compared to the size of the atom» ✔

Very few ⁴He²⁺ deviating largely from their path:

nucleus/centre is positive «and repels ⁴He²⁺ particles»
OR
nucleus/centre is «more» dense/heavy «than ⁴He²⁺ particles and deflects them»
OR
nucleus/centre is «very» small «compared to the size of the atom» ✔

Do not accept the same reason for both M1 and M2.

Accept “most of the atom is an electron cloud” for M1.

Do not accept only “nucleus repels ⁴He²⁺ particles” for M2.

(b(i))

Subsequent experiments showed electrons existing in energy levels occupying various orbital shapes.

Sketch diagrams of 1s, 2s and 2p.

[2]

Markscheme

1s AND 2s as spheres ✔

one or more 2p orbital(s) as figure(s) of 8 shape(s) of any orientation (p_x, p_y p_z) ✔

(b(ii))

State the electron configuration of copper.