4B - Alkenes definitions

Question 1

Alkene

Answer 1

The hydrocarbon homologous series with one C=C double bond.

General formula = C_nH_2n

Question 2

Addition polymerisation

Answer 2

Formation of a very long molecular chain (addition polymers), by repeated addition reactions of many unsaturated alkene molecules (monomers)

Question 3

Atom economy = ?

Answer 3

Atom economy = (sum of molar masses of desired product / sum of molar masses of all products) x 100

Question 4

Cis-trans isomerism

Answer 4

A special type of E/Z isomerism in which there are two non-hydorgen groups and two hydrogen atoms around the C=C bond.

Cis isomer (Z) - H atoms are on the same side

Trans isomer (E) - H atoms on each carbon are on different sides.

Question 5

E/Z isomerism

Answer 5

A type of stereoisomerism in which different groups attached to each carbon atom of the C=C bons may be arranged differently in space because of the restricted rotation of the C=C bond.

Question 6

Electrophile

Answer 6

An atom (or group of atoms) which is attracted to an electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond

Question 7

Percentage yield = ?

Answer 7

Percentage yield = (Actual yield / Theoretical yield) x 100

Question 8

Pi bond (π bond)

Answer 8

A bond formed by the sideways overlap of two p-orbitals, with the electron density above and below the plane of the bonding atoms.

Question 9

Polymer

Answer 9

A large molecule formed from many thousands of repeat units of smaller molecules known as monomers

Question 10

Sigma bond (σ bond)

Answer 10

A bond formed by the overlap of one orbital from each bonding atom, consisting of two electrons and with the electron density centered around the one directly between the nuclei of the two atoms

Question 11

Stereoisomers

Answer 11

Compounds with the same structural formula but with a differet arrangement of the atoms in space