Question | Answer |
Instantaneous dipole - induced dipole bonds | a dipole is formed from the uneven distribution of electrons over a molecule. This dipole induces a dipole in another molecule |
electronegativity | a measure of the attraction of an atom for a pair of electrons in a covalent bond. F is the most electronegative followed by O, N, Cl and Br. |
permanent dipole - permanent dipole bonds | attractive forces between polar molecules |
hydrogen bonds | attractive forces between the lone pairs on an O, N or F and a delta positive hydrogen |
enthalpy change of solution | the enthalpy change when one mole of a solute dissolves to form an infinitely dilute solution. Insoluble compounds have a positive value, soluble compounds have a negative value |
lattice enthalpy | the enthalpy change when one mole of a solid lattice is formed from its gaseous ions |
enthalpy change of hydration | the enthalpy change when a solution of ions is formed from one mole of gaseous ions. It always has a negative value |
strong acid | an acid which fully dissociates in water. Has a strong tendency to donate protons |
strong base | fully dissociates in water |
weak acid | only partially dissociates in water |
buffer solution | a solution which can resist changes in pH on the addition of small amounts of acid or alkali |
addition reaction | where 2 or more molecules react to form a single larger molecule |
condensation reaction | two molecules react together to form a larger molecule with the loss of water |
elimination reaction | reaction of 2 molecules to form a larger molecule with the elimination of a smaller molecule (usually water or HCl) |
substitution reaction | when one functional group in an organic molecule is substituted for another one |
oxidation | loss of electrons, increase in oxidation number, reaction with oxygen, removal of hydrogen |
reduction | gain of electrons, decrease in oxidation number, reaction with hydrogen, removal of hydrogen |
hydrolysis | reaction with water or hydroxide ions |
radical | a species with an unpaired electron |
electrophile | a positively charged ion or a molecule with a delta positive charge that will be attracted to a negatively charged area and react by accepting a lone pair of electrons to form a covalent bond |
nucleophile | a molecule or negatively charged ions with a lone pair of electrons that it can donate to a positively charged atom to form a covalent bond |
carbocation | a positively charged carbon atom |
saturated | contains single bonds only |
unsaturated | contains multiple bonds |
Pharmacophore | functional group(s) that determine the pharmacological (curing) activity of the molecule, makes it a successful medicine. |
Receptor site | a specific set of functional groups that can bind one only molecule, which is complementary (stereospecific) to the site. Usually the receptor site can bind a specific optical or geometric isomer. |
Lead compound | a compound that shows some promise in curing a disease. This compound can further be modified to produce better results |
Molecular recognition | this is the group of atoms that is involved in binding to the receptor. The structural fragment fits precisely into the shape of the receptor, and functional groups on both are correctly positioned to interact. |
Chromophore | part of the molecule responsible for colour. Usually has conjugated electrons or extended delocalised system. Functional groups such as –NH2, -OH, -NR2 are often present. They also contain lone pairs that can get involved in the delocalised system. |