Chemistry Dictionary Flashcards
Define: acidic oxides
Non-metal oxides which dissolve in water such as SO2 or NO2
Define: acid
A solution containing more hydrogen ions than hydroxide ions (ph <7)
Define: alkali
A soluble base which when dissolved in water forms a solution containing more hydroxide ions that hydrogen ions (pH>7)
Define: alloys
A mixture of two or more metals (or carbon). The physical properties of individual metals are changed when made into an alloy
Define: ammonia
NH3, an alkaline has made by heating an ammonium salt with an alkali, eg ammonium chloride and sodium hydroxide
Define: anode
The positive electrode in electrolysis and where oxidation occurs
Define: anodising
A process used to thicken the protective oxide layer on aluminium
Define: atomic number
The no. Of protons in The nucleus of an atom
Define: base
A substance which reacts with an acid to produce a salt and water usually the oxide or hydroxide of a meta
Define: bitumen
The last fraction produced by the fractional distillation of oil with the highest melting/boiling point used for road and roofing
Define: carbohydrates
A group of carbon compounds with the general formula Cx(H2O)y which living organisms can use as an energy source by respiration
Define: cathode
The negative electrode in electrolysis and where reduction occurs
Cathodic protection
A method of protecting iron corrosion by making it the negative electrode of a cell. The iron becomes “coated” with electrons which stops it from losing its own, or from rusting
Define: coal
A fossil fuel formed from the remains of plants over millions of years at a high temperature and pressure
Define: coke
The product remaining after coal has been roasted in the absence of air to remove impurities such as sulphur
Define: concentrated solution
Contains a large amount of solute compared to the volume of solvent
Define: condensation polymer
A type of polymer in which the monomer units are joined together by a condensation reaction
Define: crystal
A three dimensional array (or network) of atoms, ions or molecules which repeats itself over and over to give a large unit which has flat sides and constant angles
Define: crystal lattice
The regular three-dimensional arrangement of partials (often ions) in a crystalline structure
Define: decomposition
The breaking down if a single compound into two or more products
Define: dehydrating reagent
A substance that is able to remove water from other chemicals
Define: delocalised electrons
Electrons that are not closely attached to particular atoms and so can move easily between atoms in a structure
Define: diamond structure
Carbon atoms covalently bonded in a tetrahedral structure giving great strength to the crystal. Non-electrical conductor, very hard and shiny
Define: diesel
A fraction obtained from crude oil distillation used in cars and trucks
Define: dilute solutions
Solution containing small amounts of solute compared to the volume of solvent
Define: disaccharide
A type of carbohydrate formed by the joining together of two monosaccharide molecules
Define: displacement reaction
A reaction in which a metal is formed from the solution of its ions by adding a metal higher in the electrochemical series
Define: distillate
The liquid that is collected after distillation
Define: Distillation
a physical method of separating a mixture of different liquids by using their different boiling points
Define: ductile
Describes a solid (metal) that can be drawn out into a wire without breaking
Define: electrode potential
A measure of how easily a metal forms ions in solutions
Define: electrolyte
A solution or metal that conducts electricity and is decomposed by it
Define: electron clouds
Are regions within the energy levels of an atom in which electrons can be found. Each electron cloud can hold a max of two electrons
Define: electroplating
An electrolysis process that deposits a layer of metal on a negative electrode made from another metal
Define: element
A substance that cannot be split up into simpler substances by chemical means. It contains only one type of atom and all its atoms have the same atomic number (no. Of protons)
Define: empirical formula
Gives the simplest ratio of atoms (or ions) of the different elements present in the compound
Define: end-point
The same as the neutralisation point in titrations
Define: energy levels
The “layers of electrons around an atom
Define: fermentation
A process by which carbohydrates are converted into ethanol and carbon dioxide by enzymes found in yeast
Define: ferroxyl indicator
A solution used in corrosion experiments with iron. It turns blue when iron is being oxidised and pink when reduction occurs
Define: galvanising
Is the protection of iron by coating it with zinc
Define: haber process
The industrial manufacture of ammonia (NH3) from hydrogen and nitrogen
Define: homologous series
A group of carbon compounds with similar chemical properties that can be represented by General formula
Define: hydrolysis
A chemical reaction in which a substance is broken down into smaller molecules by reacting with water
Define: immiscible
When two liquids do not mix together but form two layers, one on top of the other
Define: inert
Unreactive
Define: insoluble
Substance is said to be insoluble if it does not dissolve in a solvent
Define: isomer
Compounds with the same molecular formula but different structural formulae
Define: isotope
Atoms of an element that have the same atomic number but different mass numbers bc they have different numbers of neutrons in the nucleus
Define: macromolecule
A very large molecule containing many atoms
Define: malleable
Describes a solid (metal) that can be beaten out into sheets without breaking
Define: mass spectrometer
An instrument used for finding the relative atomic mass of elements. It measures the amounts of the different isotopes of an element
Define: miscible
Two liquids that Mix together completely
Define: mobility of ions
A measure of how fast ions move during electrolysis
Define: molarity
A measure of the concentration of a solution in moles per litre (mol l-1)
Define: monosaccharide
A type of carbohydrate consisting of one saccharide unit per molecule eg. Glucose
Define: natural gas
Fossil gas consisting mainly of methane
Define: organic
Compounds containing carbon except carbon dioxide or carbonates
Define: Ostwald process
The industrial manufacture of nitric acid (HNO3) from ammonia
Define: oxidising agent
A substance that takes electrons from (oxidises) other substances. The oxidising agent itself is reduced
Define: paraffin
A liquid fuel extracted from crude oil by fractional distillation. Used for lighting and cooking
Define: petrochemical
A chemical that has been made from petroleum eg. Plastics
Define: panar molecule
A flat molecule eg. Water
Define: plastic
A common term used to describe polymers that can be moulded by heat or pressure
Define: polymerisation
The process by which a polymer is formed
Define: polysaccharide
A type of carbohydrate formed by joining together a large number of monosaccharide molecules eg. Starch
Define: precipitate
An insoluble solid is formed when certain solutions are mixed
Define: rate of reaction
A measure of how quickly a reaction is proceeding
Define: reducing agent
A substance that gives electrons to (reducing) other substances. The reducing agent itself is an oxide
Define: reducing sugar
A type of carbohydrate that gives a positive test with Benedict’s solution
Define: reduction
A chemical change in which electrons are gained
Define: refining
This involved the removal of impurities from q substance or the removal of components from a mixture
Define: residue
The solid chemical left after a reaction or the solid substance that is trapped on filter paper after filtration
Define: respiration
A process whereby carbohydrates are broken down to release energy in plants and animals
Define: Sacrificial protection
A method of protecting metal by attaching it to a more reactive metal
Define: saturated solution
A solution in which no more solute will dissolve at a given temperature
Define: solute
The solid that dissolves in w solvent to form a solution
Define: subatomic particles
The small units that make up the atom: protons, electrons, neutrons
Define: synthetic polymers
Polymers that do not occur naturally
Define: titre
The value of a titration in millilitres
Define: triatomic molecule
A molecule with 3 atoms in it
