Glossary - A Flashcards
Absolute Temperature
A temperature based on the thermodynamic (ideal gas) scale, measured from absolute zero; absolute temperature = (temperature in Celsius + 273) K.
Absolute Zero
The temperature to which substances cannot be cooled. Corresponds to complete absence of heat; the temperature at which all ionic, molecular and atomic vibrations cease and at which the pressure and volume of an ideal gas are zero.
Absorbance
Logarithm of the fractional transmission of light (often at a specified wavelength) through a sample.
Accurate Measurement
A measurement obtained using accurately calibrated instruments correctly and where no systematic errors arise: close to true value of the measurement.
Acid
A proton donor and/or electron pair acceptor
Acid-Base Indicator
A weak acid whose dissociated and undissociated forms in aqueous solution are different colors. The proportion of the two colored forms vary with pH; used to show changes in the pH of aqueous solutions.
Acid-Base Reactions
Transfer of protons/ hydrogen ions from an acid to a base.
Acidic Oxide
A covalent oxide, usually an oxide of a non-metal, that reacts and dissolves in water to form a solution of an acid - if insoluble in water, oxide reacts with alkalis to give salts.
Addition Polymerization
A type of polymerization that occurs when alkene-based monomers undergo repeated addition reactions to form a single molecule.
Addition Reaction
A reaction in which two (or more) molecules combine to form a single molecule.
Alcohols
A homologous series of organic compounds containing functional group -OH and general formula CnH2n+1OH.
Aldehydes
A homologous series of compounds with the general formula RCHO, where the -CHO group (the aldehyde group) consists of a carbonyl group attached to a hydrogen atom; R is usually an alkyl or aryl group.
Aliphatic
An organic compound that has carbon atoms arranged in a chain or branched form rather than atomic ring.
Alkali
A strong base which is soluble in water; alkalis are group 1 metal hydroxides and barium hydroxide.
Alkali Metals
The group of very reactive metals in group 1 of the periodic table;they react
with water to release hydrogen gas and form strongly alkaline solutions.
Alkanes
Saturated hydrocarbons which have the general formula CnH2n+2 (if acyclic).
Alkyl Group
a group, with the general formula CnH2n+1, obtained by removing a hydrogen atom from an alkane, and usually represented by R.
Alkynes
Unsaturated hydrocarbons with a carbon–carbon triple bond and with the general formula CnH2n–2 (if acyclic).
Allotrope
Different structures of an element.
Allotropy
The ability of an element to exist in
different structural forms or allotropes.
Alloy
Mixture with metallic properties made up of two or more metals, or which contains metals and carbon.
Amide Link
A chemical bond formed between
two molecules when the carboxyl group of one molecule reacts with the amine group of the other molecule, thereby releasing a molecule of water.
Amide
A homologous series of organic
compounds with the general formula RCONH2.
Amines
Organic compounds derived by replacing one or more of the hydrogen atoms in ammonia by alkyl groups.
Amount
A physical quantity indicating the number of moles of a substance present in a sample.
Ampere
The SI unit of electrical current:a current of one ampere (amp) is a flow of one coulomb of charge per second (1A = 1Cs–1).
Analyse
Interpret data to reach conclusions.
Anhydrous Salt
A salt that does not have its
water of crystallization.
Anion
A negatively charged ion which migrates
to the anode (positive electrode) during
electrolysis.
Annotate
Add brief notes to a diagram or graph.
Anode
Where oxidation (the loss of electrons) occurs during an electrochemical process; in an electrolytic cell the anode is the positive electrode.
Anomalous Data
Data with unexpected values that does not match the relationship predicted by the hypothesis.
Aromatic
An organic compound that contains
a benzene ring.
Atomic Number
The number of protons in the nucleus of an atom; in atoms the atomic number is also equal to the number of extra- nuclear electrons.
Atomic Radius
Half the distance of the closest approach of the nuclei of atoms in the crystal or molecule of a chemical element.
Average Bond Enthalpy
Enthalpy change per mole when one mole of the same type of covalent bond is broken in the gas phase for many similar molecules.
Average Rate of Reaction
Calculated by dividing the total change in reactant or product concentration by the time for the reaction to end.
Avogadro’s Law
At a specified temperature and pressure, equal volumes of (ideal) gases contain equal numbers of moles of particles; there is a directly proportional relationship between the volume of gas, V, and the amount of particles (at constant pressure), n: V
Avogadro’s Constant
The number of atoms in exactly 12 grams of carbon-12; it has units of per mol (mol–1).
