Physical chemistry

• First ionisation energy - the enthalpy change when 1 electron is removed from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions
• Second ionisation energy - enthalpy change when 1 mole of electrons are removed from 1 mole of 1+ gaseous ions to form 1 mole of gaseous 2+ ions
• Polar -molecule where charge isn't symmetrically distributed causing a dipole
• Bond enthalpy - energy required to break a particular covalent bond in one mole of a molecule in the gas state
• Specific heat capacity - amount of heat energy needed to raise the temperature of 1kg of a substance by 1 k
• Activation energy - minimum energy required for a reaction to take place
• Mean bond enthalpy - average energy needed to break one mole of a certain type on bond over a range of compound in the gaseous state
• Hess' law - the enthalpy change for a chemical reaction is the same whatever route is taken from reactants to products
• Relative isotopic mass - mass of an atom of an isotope of an element relative to 1/12 the mass of carbon-12
• Relative atomic mass - average mass of an atom of an element relative to 1/12 the mass of an atom of carbon-12
• Relative molecular mass - the average mass of a molecule relative to 1/12 the mass of carbon-12
• Lattice enthalpy - enthalpy change when one mole of an ionic compound is formed from its gaseous ions under standard condition
• Standard enthalpy of combustion - enthalpy change when one mole of a substance is completely burned in oxygen under standard conditions with all elements in their standard states
• Standard enthalpy of formation - enthalpy change when 1 mole of a substance is formed from its consecutive elements under standard conditions with all elements in their standard states
• Le chateliers principle - if a system at equilibrium is disturbed the equilibrium moves in the direction that tends to reduce the disturbance
• Ideal gas equation - pV =nRT pressure=Pa volume= M3 temperature= K
• The Aufbau principle - electrons enter the lowest available energy level
• Pauli's exclusion principle - no two electrons can have the same 4 quantum numbers (no 2 electrons can go into orbital unless they have opposite spin)
• Hund's rule of maximum multiplicity - when in orbitals of equal energy, electrons try to remain impaired
• Boyles law - pressure x volume = constant
• Charles's law - volume/temperature = constant
• Gay-Lussac's law = pressure /temperature = constant
• Activation energy - minimum amount of energy required for a reaction to occur
• Enthalpy change = q (J) = m (g) x c (specific heat capacity) x temperature change (K)
• Enthalpy changes for KJ mol-1 do the enthalpy change value (q) divided by the number of moles (n)
• Van Der Waals forces - also called induced dipole dipole forces they are the weakest intermolecular force and occur between all molecules and the greater the number of electrons the greater the strength of the force due to larger temporary dipoles being created due to larger fluctuations in electronegativity
• Permanent dipole dipole forces - occur in polar molecules where the delta negative charge of one molecule is electrostatically attracted to the delta positive charge of another molecule
• Catalyst - increase the rate of the chemical reaction by providing an alternative route with a lower activation energy