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Chemistry OCR Vocab > Key words/formulas and their points > Flashcards

Flashcards in Key words/formulas and their points Deck (64)
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1

Acid

A species that is a proton donor

2

Activation energy

The minimum energy required to start a reaction by breaking bonds

3

Addition reaction

A reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule

4

Alkali

A type of base that dissolves in water forming hydroxide ions

5

Alkanes

CnH2n+2

6

Anion

Negative ion

7

Atom economy

atom economy = molecular mass of the desired product / sum of molecular masses of all products x100

8

Orbital

A region within an atom that can hold up to two electrons with opposite spins

9

Average bond enthalpy

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 specie

10

Atomic number

Protons in nucleus

11

Avogadros constant

Number of atoms per mole of a carbon - 12 isotope (6.02x1023)

12

Base

Proton acceptor

13

Catalyst

A substance that increases rate of a chemical reaction without being used up

14

Cation

Positively charged ion

15

Cis isomerism

H atoms on same side

16

Trans isomerism

H atoms in different sides

17

Covalent bond

Shared pair of electrons

18

Curley arrow

Show the movement of a pair of electrons

19

Diative covalent bond

Shared pair of electrons provided by one bonding atom only

20

Displacement reaction

Where a more reactive element replaces a less reactive element from an aqueous solution of latter's ions

21

Dynamic equilibrium

-closed system
-forward reaction rate is equal to reverse reaction rate

22

Electronegativity

A measure of attraction of a bonded atom for a pair of electrons in a covalent bond

23

Sheilding

Repulsion of electrons from different inner shells

24

Electrophile

An atom that us attracted to an electron rich centre or atom where it accepts a pair of electrons to form a new covalent bond

25

Elimination reaction

Removal of a molecule from a saturated molecule to make an unsaturated molecule

26

Empirical formula

Simplest whole-number ratio of atoms of each element present in a compound

27

Endothermic

Enthalpy of products is greater than enthalpy of reactants resulting in heat being taken in from surroundings

28

Standard enthalpy change of combustion

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

29

Standard enthalpy change formation

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.

30

Standard enthalpy change of reaction

The enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all reactants and products being in their standard states.

31

Esterfication

Alcohol + carboxylic acid > ester + water

32

Exothermic

Enthalpy of the products is smaller than the enthalpy of the reactants resulting in heat loss to surroundings

33

Greenhouse effect

The process in which the absorption and subsequent emission of IR by atmospheric gasses warms the lower atmos and planets surface

34

Group

-Vertical column
-similar chemical properties
-same number of outer electrons

35

Hess's Law

If a reaction can take place by more than one route and the initial and final conditions are the same, the total enthalpy change is the same for each route.

36

Heterolyric fission

The breaking of a covalent bond with both of the bonded electrons going to one of the atoms, forming a cation (+ ion) and an anion (– ion).

37

Homolytic fission

The breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals.

38

Homologous series

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

39

Ionic bond

An electrostatic attraction between oppositely charged ions

40

First ionisation energy

The energy required to remove one electron from each atom in one mole of gaseous atoms to form a gaseous 1+ ion

41

le Chatelier's Principle

When a system in dynamic equilibrium is subjected to a change, the position of equilibrium will shift to minimise the change.

42

Mass number

Protons and neutrons in the nucleus

43

Metallic bonding

Electrostatic attraction between positive metal ions and delocalised electrons

44

Mole

Amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon 12 isotope

45

Nucleophile

An atom (or group of atoms) that is attracted to an electron- deficient centre or atom, where it donates a pair of electrons to form a new covalent bond.

46

Nuclophilic substitution

A type of substitution reaction in which a nucleophile is attracted to an electron-deficient centre or atom, where it donates a pair of electrons to form a new covalent bond.

47

Percentage yield

% yield = actual amount, in mol, of product/ theoretical amount, in mol, of product x100

48

Period

-horizontal row of elements
-trends in properties

49

Periodicity

Regular periodic variation of elements with atomic number and position in the periodic table

50

Pi-bond

Overlap of p orbitals

51

Propagation

Build up of products in a chain reaction

52

Radical

Species of an unpaired electron

53

Relative atomic mass

The weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12.

54

Relative formula mass

The weighted mean mass of a formula unit compared with one- twelfth of the mass of an atom of carbon-12.

55

Relative isotopic mass

The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12.

56

Relative molecular mass

The weighted mean mass of a molecule compared with one- twelfth of the mass of an atom of carbon-12

57

Saturated hydrocarbon

Single c-c bonds

58

Specific heat capacity

q=mc🔺t

C=4.18

59

Standard conditions

Pressure of 100kPa
Temperature of 298K
Concentration of 1 mol dm-3

60

Stereoisomers

Same structural formula but different arrangement of atoms in space

61

Structural isomers

Same molecular formula but different structural arrangement of atoms

62

Substitution reaction

An atom or group of atoms is replaced

63

Termination

Two radicals combine to form a molecule

64

Unsaturated hydrocarbon

C-C multiple bonds