Unit 2 Definitions

Question 1

Define: General formula

Answer 1

The simplest algebraic formula for a member of a homologous series

Question 2

Define: Structural formula

Answer 2

The minimal detail that shows the arrangement of atoms in a molecule

Question 3

Define: Skeletal formula

Answer 3

The simplified organic formula shown by removing hydrogen atoms from alkyl chains leaving just a carbon skeleton and functional groups

Question 4

Define: Homologous series

Answer 4

A series of organic compounds having the same functional group, but with each successive member differing by CH2

Question 5

Define: Functional group

Answer 5

The group of atoms responsible for the characteristic reactions of a compound

Question 6

Define: Structural isomers

Answer 6

Compounds with the same molecular formula, but different structural formulae

Question 7

Define: Stereoisomers

Answer 7

Compounds with the sane structural formula, but with a different arrangement in space

Question 8

Define: E/Z isomerism

Answer 8

An example of stereoisomerism, in terms of restricted rotation about a double bond and the requirement for two different groups to be attached to each carbon atom of the C=C group

Question 9

Define: Cis-Trans isomerism

Answer 9

A special case of E/Z isomerism in which two of the substituent groups are the same

Question 10

Define: Homolytic fission

Answer 10

Forming two radicals

Question 11

Define: Heterolytic fission

Answer 11

Forming a action and an anion

Question 12

Define: Radical

Answer 12

A species with an unpaired electron

Question 13

Define: Electrophile

Answer 13

An electron pair acceptor

Question 14

Define: Nucleophile

Answer 14

An electron pair donar

Question 15

Define: Standard conditions

Answer 15

100 kPa (1 atmosphere), 298 K (25 dc), 1.0 moldm-3

Question 16

Define: Enthalpy change of formation

Answer 16

The enthalpy change that takes place when one mole of a compound is formed from its constituent elements in their standard states under standard conditions

Question 17

Define: Enthalpy change of reaction

Answer 17

The enthalpy change that accompanies a reaction in molar quantities expressed in a chemical equation under standard conditions, all substances being in their standard states

Question 18

Define: Enthalpy change of combustion

Answer 18

The enthalpy change that takes place when one mole of a substance completely reacts with oxygen under standard conditions, all substances being in their standard states

Question 19

Define: Average bond enthalpy

Answer 19

The average enthalpy change that takes place when breaking by homolytic fission 1 mol of a given type of bond in the molecules of a gaseous species

Question 20

Define: Catalyst

Answer 20

A substance which speeds up a reaction without being consumed by the overall reaction

Question 21

State: Le Chatiliers principal

Answer 21

If a a change is made to a system in dynamic equilibrium then the position of the equilibrium shifts to counteract the change

Question 22

Emperical Formula

Answer 22

The smallest whole number ratio of atoms of each element in a compound

Question 23

Molecular formula

Answer 23

The actual number of atoms of each element present in a compound

Question 24

Displayed formula

Answer 24

the relative positioning of atoms and their bonds

Question 25

Curly arrow

Answer 25

the movement of electron pairs resulting in the breaking or formation of covalent bonds