UNIT CH1 - Controlling and Using Chemical Changes

Controlling and Using Chemical Changes (in order to make things, produce energy and solve environmental problems)

This unit begins with some important fundamental ideas about atoms and the use of the mole concept in calculations. Three key principles governing chemical change are then studied, viz., the position of equilibrium between reactants and products, the energy changes associated with a chemical reaction and the rate at which reactions take place. These principles are then applied to some important problems in the fields of chemical synthesis, obtaining energy and the maintenance of the environment.

Topic 1.1 Basic ideas about atoms

Candidates should be able to:

(a) describe electrons, protons and neutrons in terms of their relative charges and masses, and the distribution of charges and mass within atoms;

(b) understand the terms atomic number, mass number, isotope, and the connection between atomic numbers and mass numbers;

(c) deduce, given atomic and mass numbers, the numbers of protons, neutrons and electrons in specified isotopes;

(d) explain the formation of ions from atoms by the loss or gain of electrons;

(e) describe the nature of alpha and beta - particles and of gamma radiation and recall their behaviour in electric fields and their relative penetrating powers;

(f) describe and explain the changes in mass number and atomic number resulting from alpha and beta particle emission;

(g) describe the adverse consequences for living cells of exposure to alpha radiation and to ¥á - and ¥â - emitters;

(h) explain what is meant by the half-life of a radioactive isotope; perform simple calculations involving integral numbers of half-lives;

(i) apply their knowledge of radioactive decay and half-life ((e) - (h)) to contexts in health, medicine, radio-dating and analysis;

(j) understand and explain the significance of standard molar ionisation energies of gaseous atoms and their variation from one element to another;

(k) describe and explain how information about the electronic structure of atoms may be deduced from values of successive ionisation energies;

(l) describe the shapes of s and p orbitals;

(m) recall the appropriate s, p and d orbital occupations for elements 1 - 36 (using 'arrows in boxes' or otherwise) and relate these to position in the Periodic Table.

(n) explain the origin of emission and absorption spectra in terms of electron transitions between atomic energy levels;

(o) describe and interpret the visible atomic spectrum of the hydrogen atom (first 4 lines in the Balmer Series only);

(p) recall the direct proportionality between energy and frequency, as implied by E = hf, and the inverse relationship between frequency and wavelength; (No calculations will be set.)

(q) show understanding of the relationship between the frequency of the convergence limit of the Lyman Series and the ionisation energy of the hydrogen atom.