Form 4 Chapter 2 - The Structure of the Atom

Chemistry SPM notes for Chapter 2.

Chapter 1 should be simple enough, usually 0-2 questions will come out in Paper 1 only.

Note that you should read through some references as the following notes will not be detailed.

I will just focus on some of the parts. (Disclaimer: I am not predicting which questions will come out in SPM. You can copy & print out the notes below for easier reading/preparation for SPM.)

Experiment to investigate the kinetic theory of matter (Paper 1, Paper 3):

1) Diffusion in a gas - Liquid bromine, gas jar, gas jar cover

2) Diffusion in a liquid - Water, potassium permanganate crystals, petri dish

3) Diffusion in a solid - Jelly, boiling tube, potassium permanganate crystal, stopper

Calculation of a size of oil molecule (Removed from syllabus, just read if you want to. Thanks for pointing it out!):

Volume of 50 drops = V

Volume of 1 drop = v/50

Tiny droplets/Small particles = (V/50)/n

Diameter of small particles = d = 2r

Volume of oil particle = πr^2h = (V/50)/n

Since h is the size of particle,

Note that burette reading should always be in 2 d.p(decimal places)

Changes in the states of matter:

(Quite straightforward here...)

Sublimation - iodine, ammonium chloride, solid carbon dioxide (dry ice).

Experiment: To determine the melting/cooling point of naphthalene (Paper 2, Paper 3)

Naphthalene can be replaced with acetamide.

*When plotting a graph, ensure that:

a. axes are labelled with units

b. points are transferred correctly

c. curve is smooth

To explain the graph (for naphthalene):

During heating:

- the kinetic energy of molecules increases

- the distance between the molecules increases

- the forces of attraction between the molecules become weaker

During cooling:

- the kinetic energy of molecules decreases

- the distance between the molecules decreases

- the forces of attraction between the molecules become stronger

Atomic Structure (Paper 1, Less likely in Paper 2)

John Dalton

- all elements are made up of small indivisible particles called atoms

J.J.Thompson

- discovered negatively charged particles called electrons

Ernest Rutherford

- discovered positively charged particles called protons

Neils Bohr

- atoms have electrons arranged in orbits called electron shells surrounding the nucleus

James Chadwick

- discovered electrically neutral particles called neutrons

Nucleon number = Number of protons + Number of neutrons

(A - nucleon number, Z - proton number, X - element)

You should know most of the elements by now. (Eg. Tin, Silver, Gold, Mercury)

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Isotopes (Paper 2)

Isotopes are atoms of the same element with the same proton number but different nucleon numbers. (same proton number but different neutron number also accepted.)

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Uses of Isotopes (Paper 1, Less likely in Paper 2)

Cobalt-60

- kill cancer cells

Carbon-14

- determine absorption rate of phosphorus in plants

- carbon dating

Uranium-235

- nuclear energy

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End of Chapter 2.
Source :http://anendlesscalm.blogspot.com/search/label/SPM%20Chemistry