Lecture 1 - Overview of periodic table. Numbering of groups, rows, etc. History of the periodic table. A review of atomic structure, electron filling. Key features of wavefunctions

Question 1

Ionisation energy / potential (of species A)

Answer 1

The molar internal energy change, ΔU, for the reaction:
A(g) -> A+(g) + e- at 0K.
Reactants and products being in their standard states. We often assume that ΔH(298 K) ≈ ΔU(0 K)

Question 2

Bond dissociation energy

Answer 2

The enthalpy change associated with the reaction in which one mole of the bond is homolytically broken, reactants and products being in the ideal gas state at 1 bar and 298.15 K

Eg for methane:
CH4(g) -> CH3-(g) + H+(G)

Question 3

Boiling point (of a substance)

Answer 3

The temperature at which the vapour pressure of the liquid is equal to the pressure exerted on it by the surroundings

Question 4

Melting point (of a substance)

Answer 4

The temperature at which the liquid and solid forms of a pure substance can exist in equilibrium

Question 5

Enthalpy of vapourisation

Answer 5

The change in enthalpy when 1 mole of a substance is converted from liquid state to gaseous state (vapour state) at its boiling point.
Values are often corrected to 298.15 K for tabulation.

Question 6

Enthalpy of atomisation

Answer 6

The enthalpy change when one mole of gaseous atoms is formed from a compound in its standard state under standard conditions.

Question 7

In hydrogen, what order do the energy of atomic orbitals increase and why

Answer 7

1s and 2s and 3s and 4s, 2p and 3p, 3d

In hydrogen all orbitals with the same value of n have the same energy - penetration and shielding don’t come into play only one electron is present