Glossary Flashcards
absolute zero
273C or 0 K. Molecules and atoms have minimum kinetic energy at this temperature.
acid
Substance capable of donating a hydrogen ion (proton).
acid rain
Rainwater that has reacted with acidic emissions from industry and has a pH less than 5.5.
acidic oxide
an oxide generally of a nonmetal that either reacts with water to form an acid or reacts with a base. acidic solution An aqueous solution in which [H+] > [OH]. At 25C the pH
actinides
The set of elements with atomic number between 90 and 103 in which the 5fsubshell is progressively filled.
addition reaction
A reaction in which a molecule binds to an unsaturated hydrocarbon forming a single carbontocarbon bond. In this process two reactant molecules become one.
aliquot
A volume of liquid measured by a pipette. alkali A soluble base.
alkali metals
Group 1 metals.
alkanes
Hydrocarbons with only single bonds between carbon atoms; general formula CnH2n+2.
alkenes
Hydrocarbons with one double bond between two carbon atoms; general formula CnH2n.
alkyl group
A group obtained by removing a hydrogen atom from an alkane with general formula CnH2n+1 e.g. methyl (CH3).
allotropes
Different physical forms of the same element.
alloy
A substance formed when other materials (e.g. carbon other metals) are mixed with a metal.
alpha particle
A 42He nucleus emitted from the nucleus of an atom during radioactive decay.
amorphous
Without structure.
amount of substance
A measure used by chemists for counting particles; the unit is the mole.
amphiprotic
The ability to act as an acid or a base.
anion
A negatively charged ion.
annealing
Heating a metal to a moderate temperature and then allowing it to cool slowly to make it softer and more ductile.
anode
An electrode at which an oxidation reaction occurs.
atom
The smallest part of an element that can take part in a chemical reaction.
atom economy
A method of tracking the atoms in a reaction equation to calculate the mass of the atoms of reactants actually used to form product as a percentage of the total mass of reactants.
atomic number
The number of protons in the nucleus of an atom.
atomic radius
Half the distance between the nuclei in a molecule consisting of identical atoms.
Avogadros number (NA)
- NA the number of particles in a mole;
- NA = 6.023 1023 mol1.
- NA is the number of elementary particles (atoms) in exactly 12 g of carbon-12. is number is equal to 6.02 × 1023.
Avogadros law
At the same temperature and pressure equal volumes of all gases contain the same number of molecules.
base
A substance capable of accepting a hydrogen ion (proton).
basic oxide
An oxide of a metal which either reacts with water to form hydroxide ions or reacts with H3O+ ions.
basic solution
A solution where [H3O+] 7.
biosphere
That part of the Earths environment that supports life.
bonding electrons
Outershell electrons involved in covalent bonding.
Boyles law
P V1 at constant temperature.
brittle
Shatters when given a sharp tap.
BrnstedLowry theory
A theory that defines an acid as a proton (hydrogen ion) donor and a base as a proton acceptor.
carbonoxygen cycle
The path taken by carbon and oxygen atoms as they react to form new compounds and move around the biosphere.
catalyst
A substance that increases the rate of a reaction but are not consumed in the reaction. cathode An electrode at which a reduction reaction occurs.
cation
A positively charged ion.
Charles law
V T at constant pressure.
chlorination
Reaction with chlorine.
chlorofluorocarbons
Synthetic compounds containing chlorine fluorine and carbon atoms e.g. CF2Cl2.
colloids
Very small particles spread throughout a liquid solid or gas. These particles are bigger than single molecules but so small that they do not settle on standing.
combined gas equation
P1V1 = P2V2 n1T1 n2T2
combustion
Reaction with oxygen.
compound
A pure substance composed of atoms of two or more elements which have chemically combined in fixed proportions.
concentration
A measure of the amount of solute dissolved in a given quantity of solvent or solution.
conductivity of electricity
Allows an electric current to pass through.
conjugate acid
The conjugate acid of a base contains one more hydrogen ion (proton) than the base.
conjugate base
The conjugate base of an acid contains one less hydrogen ion (proton) than the acid.
conservation of mass
see law of conservation of mass.
core charge
the attraction felt by the outershell electrons to the nuclear charge. Core charge can be calculated as atomic number all electrons except those in the outer shell.
corrosion
The reaction of a metal with oxygen and other substances in its environment.
covalency
The number of electrons an element shares in a covalent molecular compound.
covalent bond
The force of attraction formed when one or more pairs of electrons are shared between two nuclei.
covalent layer lattice
A twodimensional array of atoms held together by covalent bonds. Weak forces operate between the layers.
covalent molecular lattice
An arrangement of molecules into a lattice; the attractive forces between the molecules are weak. covalent network lattice An arrangement of atoms into a lattice in which there are strong covalent bonds between the atoms in all three dimensions.
crosslinks
Covalent links between polymer chains. The extent of crosslinking varies depending on use.
crystalline solid
A solid with a regular arrangement of particles.
crystallisation
Some solute comes out of solution to form crystals.
customised
Manufactured with specific properties to meet a need.
dblock
A block of elements in the periodic table known as the transition metals; the atoms of these metals have outershell electron configurations of d1s2 to d10s2.
decomposition
The breaking down of a compound to form two or more other compounds or elements.
delocalised electrons
Electrons that are not restricted to a region between two atoms.
desalination
The removal of salts from seawater to obtain fresh water.
dilute
A dilute solution is one in which the ratio of amount of solute to solvent or solution is low. dilution The addition of solvent to a solution to reduce its concentration.
dipole
A molecule that has two oppositely charged poles or ends.
dipoledipole interaction
Attractions between dipoles.
diprotic
A diprotic acid is capable of donating two hydrogen ions (protons); e.g. H2SO4.
dispersion force
The attraction that exists between molecules because of the instantaneous dipoles that form as electrons move randomly.
displacement
A process in which one substance replaces another.
dissociation
The separation of positive and negative ions as an ionic lattice melts or dissolves.
distillation
The separation of a liquid from a solid or other liquid by heating to cause evaporation followed by cooling to cause condensation.
dry ice
Solid carbon dioxide.
ductile
Able to be drawn into a thread.
elastic
Able to be stretched and then return to original shape when stretching force is removed.
elastomer
A material that returns to its original position after contraction or expansion.
electrochemical cell
A device that converts chemical energy into electrical energy.
electrochemical series
A list of chemical species arranged in order of their strength as oxidants.
electrolytic conductor or electrolyte
A solution or molten substance that conducts electricity by means of the movement of
electronegativity
The ability of an atom that is bonded to another atom to attract the bonding electrons towards itself.
electrovalency
The charge on an ion.
element
A substance composed of atoms with the same atomic number.
emission spectrum
A set of coloured lines on a black background obtained when light emitted by excited electrons as they move to a lower energy state is passed through a prism in a spectroscope.
empirical formula
A formula of a compound that shows the elements present and their ratio.
enhanced greenhouse effect
An increase in the temperature of the atmosphere due to an increased concentration of greenhouse gases such as carbon dioxide and water vapour.
equivalence point
The point in a titration when the reactants have reacted in their correct mole ratios.
excess reagent
Reagent that is present in an amount greater than that required in a reaction.
excited state
The state of an atom ion; etc. in which one or more electrons have absorbed energy and are not in their lowest energy levels.
fblock
A block of metallic elements in the periodic table; known as the lanthanides and actinides; in which the 4f and 5fsubshells are progressively being filled.
fermentation
The conversion of sugar solutions; in the presence of yeast to form ethanol and carbon dioxide.
filtrate
The liquid that passes through a filter.
first ionisation energy
The minimum amount of energy that is required to remove the highest energy electron from an atom; in the gaseous state.
flocculation
Small suspended particles come together to form larger heavier particles which are usually insoluble.
fossil fuels
Coal oil and natural gas; fuels derived from the remains of animal and plant matter.
fractional distillation
The separation of a mixture into different fractions; each containing a number of gases with similar boiling temperatures.
galvanic cell
A device that converts chemical energy into electrical energy.