27th June 2017

Changes to H2 Chemistry Syllabus Part 2

H2 Chemistry Syllabus 2017

Part 2 (part 1 here)

H2 chemistry syllabus 2017 updates:

Organic: Constitutional (structural) isomerism. Cis-trans isomerism, used to be geometric isomerism. Enantiomerism used to be optical isomerism.

Nitrogen Compounds (proteins): Not required to learn primary – quaternary structures, as well as list major functions of proteins in the body. Not required to recognize the twenty amino acids and describe α-helix and β-pleated sheet. Not required to describe protein components of haemoglobin. Not required to explain denaturation of proteins.

Electrochemistry: state and apply the relationship Δ = −nFEθ to electrochemical cells. spontaneous redox reaction (ΔG < 0) would mean that Ecell > 0. In other words, the extent of a redox reaction is governed by the sign and magnitude of cell, like in the case of Δ.

Since Eθcell is dependent on both temperature and concentration (Nernst equation), a non-spontaneous reaction under standard conditions can be made feasible under non-standard conditions (e.g. increasing temperature or concentration).

Similar to the use of ΔGθ to predict the feasibility of a reaction, Eθcell only gives an indication of the thermodynamic feasibility (spontaneity), i.e. based on energy consideration.

The other important aspect, the kinetic feasibility (looking at the activation energy, Ea) must also be considered in order to understand fully whether a reaction is likely to proceed on its own. 

Note that “standard conditions” for both Electrochemistry and Energetics is now 298K, 1 bar and 1 moldm-3 

Atomic structure: Describe the shapes of d orbitals. This ties in well with the explanation for splitting of degenerate (same energy level) d orbitals.

Transition elements: Describe, using the shape and orientation of the d orbitals, the splitting of degenerate d orbitals into two energy levels in octahedral complexes.

In an octahedral complex, a central metal atom is surrounded by 6 lone pairs of electrons (on the 6 ligands). dx2_y2 orbital and the dz2 orbitals have their lobes pointing at the ligands along the x and y axes, and z axis respectively, hence they experienced greater repulsion from the ligands. The dxy, dyz and dxz orbitals experienced less repulsion since their lobes do not point at the ligands along the axes. Thus the 5 d orbitals are split into 2 energy levels, with higher energy level dx2_y2 and dz2 orbitals and the dxy, dyz and dxz orbitals having the lower energy level

End of H2 Chemistry Syllabus 2017 update~


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