Chemistry Definitions Flashcards
DEFINE: electrophile
Atom or group that is attracted to an electron rich centre where it accepts a pair of electrons to form a new covalent bond
DEFINE: delocalised electrons
Electrons shared between more than 2 atoms
DEFINE: redox
Reaction where oxidation and reduction takes place
DEFINE: reflux
Continual boiling and condensing of a reaction mixture to ensure a reaction takes place without the contents of flask boiling dry.
DEFINE: nucleophile
Atom or group attracted to a election deficient centre where it donates a pair of electrons to form a new covalent bond
DEFINE: hydrolysis
Reaction with water or hydroxide ions that breaks a chemical compound into two
DEFINE: LDL
Protein responsible for carrying cholesterol and triglycerides from the liver to the tissues
DEFINE: HDL
Protein that can remove cholesterol from the arteries and transport it back to the liver for excretion
DEFINE: primary amine
Amine in which the nitrogen atom is attached to one carbon
DEFINE: peptide
Compound made of amino acids linked by peptide bonds
DEFINE: zwitterion
Di polar ionic form of an amino acids that is formed by the donation of an hydrogen ion from the carboxyl group to the amino group. Because both charges are present there is no overall charge
DEFINE: isoelectric point
The pH value at which an amino acids exists as a zwitterion
DEFINE: condensation reaction
Reaction in which two smaller molecule react to form a larger molecule and eliminate a small molecule such as water.
DEFINE: stereoisomers
Species with same structural formula but different arrangement of atoms in space
DEFINE: chiral carbon
Carbon atom attached to four different groups of atoms
DEFINE: optical isomer
Stereoisomers that are non superimposable mirror images of each other
DEFINE: biodegradable polymer
A polymer that breaks down completely into carbon dioxide and water
DEFINE: degradable polymer
A polymer that breaks down into smaller fragments when exposed to light heat or moisture
DEFINE: pharmacological activity
Beneficial/ adverse effects of a drug on living matter
DEFINE: mobile phase
Phase that moves in chromatography
DEFINE: stationary phase
Phase that does move in chromatography
DEFINE: adsorption
Process by which a solid hold molecules of a gas or liquid or solute as a thin film on the surface of a solid
DEFINE: chromatogram
Visible record showing the result of a separation of the components of a mixture
DEFINE: Rf Value
Distance moved by component divided by distance moved by solvent front
DEFINE: retention time
GC - time for the component to pass from the column inlet to the detector
DEFINE: rate of reaction
Change in concentration of a reactant or product per unit time
DEFINE: initial rate of reaction
Change in concentration of a reactant or product per unit time at the start of the reaction when t=0
DEFINE:order of a reactant
The power to which the concentration of the reactant is raised in the rate equation
DEFINE: half life
The time taken for the concentration of the reactant to reduce by half
DEFINE: reaction mechanism
A series of steps that together make up the overall reaction
DEFINE: rate determining step
The slowest step in the reaction mechanism of a multi step reaction
DEFINE: intermediate
A species formed in one step of a multi step reaction that is used up in a subsequent step and is not in the overall equation as a reactant or product.
DEFINE: dynamic equilibrium
Exists in a closed system when the rate of the forward reactions is equal to the rate of the reverse reaction
DEFINE: homogeneous equilibrium
An equilibrium in which all the species making up the reactants and products are in the same physical state
DEFINE: heterogeneous equilibrium
Equilibrium in which the species making up the reactants and products are in different physical States
DEFINE: Bronsted-Lowry acid
Proton donor
DEFINE: Brønsted-Lowry base
Proton acceptor
DEFINE: alkali
Base that dissolves in water forming OH- ions
DEFINE: neutralisation
Chemical reaction in which an acid and a base react together to produce a salt and water
DEFINE: acid base pair
Pair of species that transform into each other by gain or loss of a proton.
DEFINE: strong acid
Acid that completely dissociates in solution
DEFINE: weak acid
Acid that partially dissociates in solution.
DEFINE: Kw
Ionic product of water
DEFINE: buffer solution
Mixture that minimises small changes in pH on addition of small amounts of acid/base
DEFINE: equivalence point
Point of a titration at which the volume of one solution has reacted exactly with the volume of the second solution
DEFINE: end point
Point in a titration at which there are equal concentrations of weak acid and conjugate base forms of the INDICATOR
DEFINE: standard enthalpy change of neutralisation
Energy change accompanying the neutralisation of an acid by a base to form one mol of h2o under standard conditions
DEFINE: standard enthalpy change of formation
Energy change that takes place when one mol of a compound is formed from its constituent elements in their standard states under standard conditions
DEFINE: standard enthalpy change of atomisation
Enthalpy change that takes place when one mol of gaseous atoms forms from the element in its standard state
DEFINE: 1st ionisation energy
Enthalpy change that accompanies the removal of one electron from each atom in one mol of gaseous atoms to form one mol of gaseous 1+ ions
DEFINE: 1st electron affinity
Enthalpy change accompanying the addition of one electron to each atom in one mol of gaseous atoms to form one mol of gaseous 1- ions
DEFINE: standard enthalpy change of Solution
Enthalpy change that takes place when one mol of a compound is completely dissolved in water under standard conditions
DEFINE: standard enthalpy change of hydration
Enthalpy change that takes place when one mol of isolated gaseous ions is dissolved in water forming one mol of aqueous ions under standard conditions
DEFINE: entropy
The measure of disorder in a system
DEFINE: oxidation
Loss of electrons and increase in oxidation number
DEFINE: reduction
Gain of electrons and decrease in oxidation number
DEFINE: standard electrode potential of a half cell
The emf of a half cell compared with a standard hydrogen half cell measured at 298K 100KPa and solution concentrations of 1moldm-3
DEFINE: translation element
D block element that forms an ion with a incomplete d sub shell
DEFINE: complex ion
Transition metal ion bonded to one or more Ligands by dative covalent bonds
DEFINE: ligand
Molecule or ion that can donate a pair of electrons with the transition metal ion to form a co ordinate bond
DEFINE: co ordination number
Total number of co ordinate bonds formed between a central metal ion and its Ligands
DEFINE: ligand substitution
Reaction in which one ligand in a complex ion is replaced by another ligand
