Unit 1 - Foundation Chemistry (Key Terms) Flashcards
Alkane?
A hydrocarbon with C-C and C-H single bonds only, with the general formula Cn H2n+2.
Allotropes?
Pure elements which can exist in different physical forms in which their atoms are arranged differently. E.g. Diamond, Graphite & Buckminsterfullerene are allotropes of carbon.
Atom Economy?
The efficiency of a chemical reaction by comparing total number of atoms in the product with total number of atoms in starting materials.
Defined by:
Mass of Desired Product / Total Mass of Reactants x 100
Avogadro Constant?
The total number of particles in a mole of a substance.
Catalyst?
A substance that alters the rate of a chemical reaction but is not used up in the reaction.
Catalytic Cracking / Cracking?
With the help of a catalyst or high temperature, the breaking of long-chain alkane molecules into shorter chain hydrocarbons (alkanes & alkenes).
Carbon-neutral?
A process, in which as much carbon dioxide is absorbed from the air as is released.
Coordinate / Dative Covalent Bonding?
Covalent bonding in which both electrons in the bond come from one of the atoms in the bond.
Covalent Bonding?
A pair of electrons shared between 2 atoms.
Delocalised?
Electrons that are spread over several atoms & help to bond them together.
Dipole-Dipole Force?
An intermolecular force that results from the attraction between molecules with permanent dipoles.
Displacement Reactions?
A chemical reaction in which one or a group of atoms replaces another in a compound.
E.g. Zn + CuO –> ZnO + Cu
Displayed Formula?
The formula of a compound drawn out so that each atom & bond is shown.
Electron Pair Repulsion Theory?
A theory which explains the shapes of simple molecules by assuming that pairs of electrons around a central atom repel each other (as far away as possible).
Electronegativity?
The power of an atom to attract the electrons in a covalent bond.
Empirical Formula?
The simplest whole number ratio in which atoms in a compound combine together.
Endothermic?
A reaction in which heat is taken in as reactants change to products, the temperature drops.
Enthalpy Change?
A measure of heat energy given out or taken in when a chemical or physical change occurs at constant pressure.
Exothermic?
A reaction in which heat is given out as reactants change to products, the temperature rises.
Fraction?
A mixture of hydrocarbons with similar boiling points.
Free Radical?
A chemical species with an unpaired electron - highly reactive.