Chemistry AS unit 1 defintions

?
Atom
the basic unit of a chemical element
1 of 34
Atomic number
the number of protons in an atom
2 of 34
Mass number
the number of protons plus the number of neutrons in an atom
3 of 34
Relative atomic mass
the average mass of atoms of an element relative to 1/12 the mass of a carbon-12 atom, which is defined as 12 exactly
4 of 34
Relative isotopic mass
the mass of an atom of a particular isotope of an element relative to 1/12 the mass of a carbon-12 atom, which is defined as exactly 12
5 of 34
Element
an element is a substance consisting of atoms that all have the same atomic number
6 of 34
Ion
an ion is an atom or group of bonded atoms that have lost or gained electrons
7 of 34
Molecule
a molecule consists of two or mope atoms covalently bonded in a fixed ratio to form a single entity
8 of 34
Compound
is a substance containing two or more different types of atoms bonded together in a fixed ratio
9 of 34
Mole
the amount of substance that contains the same number of entities as there are atoms in exactly 12g of the isotope carbon-12
10 of 34
Avogadro constant NA
the number of entities in a mole of substance (6.02 x10 ^23)
11 of 34
Molar mass
is the mass in grams of a substance that contains NA molecules of the substance
12 of 34
Spectator ions
exists as a reactant and a product in a chemical reaction (species that are not directly involved)
13 of 34
Enthalpy change
the heat change that occurs during a chemical reaction at constant pressure
14 of 34
Standard conditions
1) all reagents and products are in their thermodynamically most stable state; 2) 1 atm pressure; 3) a specified temperature (298K)
15 of 34
Exothermic reaction
a process or reaction that releases energy from the system (-ve enthalpy change)
16 of 34
Endothermic reaction
a process or reaction in which the system absorbs energy from the surroundings (+ve enthalpy change)
17 of 34
Standard enthalpy change of formation
is the enthalpy change when 1 mol of substance is formed from its elements, under standard conditions
18 of 34
Standard enthalpy change of combustion
is the enthalpy change when 1 mol of a substance undergoes complete combustion, under standard conditions
19 of 34
Standard enthalpy change of neutralisation
is the enthalpy change when 1 mol of H+ ions is neutralised by 1 mol of OH- ions, to produce 1 mol of water, under standard conditions
20 of 34
Standard enthalpy change of atomisation
is the enthalpy change when 1 mol of gaseous atoms is formed from its element in its standard state, under standard conditions
21 of 34
Hess' law
states that the enthalpy change of a process is independent of the route taken to effect that change
22 of 34
Mean bond enthalpy
is the enthalpy change when 1 mol of the specified bond is broken (average value is taken and thus are approximate values) ALWAYS ENDOTHERMIC
23 of 34
Isotopes
atoms having the same number of protons but different numbers of neutrons
24 of 34
First ionisation energy
is the energy need to remove 1 mol of electrons from 1 mol of gaseous atoms to form 1 mol of gaseous ions
25 of 34
Second ionisation energy
is the energy need to remove 1 mol of electrons from 1 mol of gaseous X+ ions to form 1 mol of gaseous X2+ ions
26 of 34
Electron affinity
is the energy change when 1 mol of gaseous atoms accepts 1 mol of gaseous electrons, to form 1 mol of gaseous ions, X-
27 of 34
Ionic bond
is the attraction between a positive and negative ion, between a metal and a non-metal, electrons are transferred
28 of 34
Covalent bond
is the attraction between two nuclei and a shared pair of electrons
29 of 34
Lattice energy
is the energy change when 1 mol of ionic solid is formed from its gaseous ions, under standard conditions
30 of 34
Substitution reaction
is where 1 atom or group replaces another in a molecule
31 of 34
Reaction mechanism
is a way of representing how electrons are moved from the reactants to form the products
32 of 34
Radical
is an atom or a group of atoms with an unpaired electron
33 of 34
Addition reaction
is where two substances form a single substance
34 of 34

Other cards in this set

Card 2

Front

the number of protons in an atom

Back

Atomic number

Card 3

Front

the number of protons plus the number of neutrons in an atom

Back

Preview of the back of card 3

Card 4

Front

the average mass of atoms of an element relative to 1/12 the mass of a carbon-12 atom, which is defined as 12 exactly

Back

Preview of the back of card 4

Card 5

Front

the mass of an atom of a particular isotope of an element relative to 1/12 the mass of a carbon-12 atom, which is defined as exactly 12

Back

Preview of the back of card 5
View more cards

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »