a) recognise and describe protons, neutrons and electrons in terms of relative charge and relative mass.
b) describe the distribution of mass and charge within an atom
c) describe the contribution of protons and neutrons to the nucleus of an atom, in terms of atomic number and mass number
d) deduce the numbers of protons, neutrons and electrons in
i) an atom given its atomic number and mass number
ii) an ion given its atomic number, mass number and ionic charge
e) distinguish between the isotopes of an element in terms of their different masses and different numbers of neutrons
f) explain the terms first ionisation energy and successive ionisation energy of an element in terms of 1 mole of gaseous atoms or ions
g) explain that ionisation energies are influenced by nuclear charge, electron shielding and the distance of the outermost electron from the nucleus
h) predict the number of electrons in each principal quantum shell of an element from its successive ionisation energies
i) describe the shapes of s- and p- orbitals
j) describe the numbers and relative energies of s-, p- and d- orbitals for the principal quantum numbers 1, 2, 3 and also the 4s- and 4d- orbitals
k) deduce the electronic configurations of
i) atoms, given the atomic number (to Z=36)
ii) ions, given the atomic number and ionic charge, limited to s and p blocks up to Z=36.
NB Utilisation of sub-shell notation i.e. for oxygen 1s22s22p4.
a)
Describe ionic bonding as the electrostatic attraction between two oppositely-charged ionsb) Describe, including the use of dot-and-cross diagrams, ionic bonding, for example as in sodium chloride and magnesium oxide
c) Describe in simple terms the lattice structure of NaCl
d) Describe a covalent bond as a shared pair of electrons
e) Describe, including the use of dot-and-cross diagrams,
i) Covalent bonding for example as in H2, Cl2, O2, HCl, H2O, NH3, CH4, CO2 and ethene.
ii) Dative covalent (co-ordinate) bonding, for example as in the ammonium ion.
f) explain the shapes of and bond angles in molecules and ions by using the qualitative model of electron-pair repulsion for up to 4 electron pairs (including lone pairs), for example as in BF3 (trigonal), CO2 (linear), CH4 and NH4+ (tetrahedral), NH3 (pyramidal) and H2O (non-linear).
g) Predict the shapes of, and bond angles in molecules and ions analogous to those specified above.
h) Appreciate that, between the extremes of ionic and covalent bonding there is a gradual transition from one extreme to the other.
i) Describe electronegativity as the ability of an atom to attract the bonding electrons in a covalent bond.
j) Explain that
i) bond polarity may arise when covalently-bonded atoms have different Electronegativities.
ii) Polarisation may occur between cations of high charge density and anions of low charge density.
k) describe intermolecular forces based on permanent dipoles, as in hydrogen chloride, and instantaneous dipoles (van der Waals’ forces), as in the noble gases.
l) Decribe hydrogen bonding between molecules containing –OH and –NH groups, typified by water and ammonia
m) Describe and explain the anomalous properties of water resulting from hydrogen bonding, for example.
i) the density of ice cf water.
ii) Its relatively high freezing point and boiling point
n) describe in simple terms the giant molecular structures of graphite and diamond
o) describe metallic bonding present in a giant metallic lattice structure as the attraction of a lattice of positive ions to a sea of mobile electrons.
p) Describe, interpret and/or predict physical properties, for example: melting and boiling, electrical conductivity and the solubility in terms of
i) the types, motion and arrangement of particles (atoms, molecules and ions) and the forces between them;
ii) the different types of bonding (ionic, covalent, hydrogen, other intermolecular interactions and metallic bonding).
q) deduce the type
of bonding present from given information.
Candidates should be able to:
(a) explain that come chemical reactions are accompanied by enthalpy changes, principally in the form of heat energy; the enthalpy changes can be exothermic (DH, negative), or endothermic (DH, positive).
(b) Recognise the importance of oxidation as an exothermic process, for example in the combustion of fuels and the oxidation of carbohydrates such as glucose in respiration.
(c) Recognise that endothermic processes require an input of heat energy, for example, the thermal decomposition of calcium carbonate, and in photosynthesis.
(d) Construct a simple enthalpy profile diagram for a reaction to show the difference in the enthalpy of the reactants compared with that of the products.
(e) Explain chemical reactions in terms of enthalpy changes associated with the breaking and making of chemical bonds.
(f) Explain and use the terms:
i) enthalpy change of reaction and standard conditions with particular reference to formation and combustion.
· Standard conditions can be considered as 100kPa and a stated temperature (e.g. 298K).
ii) Average bond enthalpy (DH positive; bond breaking of 1 mole of bonds).
(g) Calculate enthalpy changes from appropriate experimental results directly, including the use of the relationship: energy change = mcDT.
(h) Use Hess’ Law to construct enthalpy cycles and carry out calculations using such cycles and relevant enthalpy terms, with particular reference to enthalpy changes that cannot be found by direct experiment, for example:
i) An enthalpy change of formation from enthalpy changes of combustion;
ii) An enthalpy change of reaction from enthalpy changes of formation;
Reaction rate assessment items to go here
Candidates should be able to:
(a) explain the features of a dynamic equilibrim
Reference should be made to the need for a closed system, the equal rates of the forward and reverse reactions and the constancy of macroscopic properties.
(b) state le Chatelier's principle and apply it to deduce qualitatively (from appropriate information) the effect of a change in temperature, concentration or pressure, on a homogeneous system in equilibrium
(c) describe and explain the conditions used in the Haber
process for the formation of ammonia, as an example of the importance of a
compromise between chemical equilibrium and reaction rate in the chemical
industry
(d) outline the importance of ammonia and nitrogen
compounds derived from ammonia, for example, fertilizers, polyamides and
explosives
(e) describe an acid as a species that can donate a proton
(f) describe the reaction of an acid as typified by hydrochloric acid with
metals, carbonates, bases and alkalis
(g) interpret the reactions in (f) using ionic equations to emphasis the role of
H+(aq)
(h) explain qualitatively, in terms of dissociation, the differences between
strong and weak acids
(i) describe ammonia as a base, in terms of its reaction with an acid (e.g.
sulphuric acid) to form ammonium salts, used in fertilisers.