Chemistry Flashcards
Definitions (23 cards)
Define relative atomic mass
The weighted mean mass of an atom of all the the isotopes compared to 1/12 of the mass of carbon 12
What is the definition empirical formula
The simplest whole number ratio of atoms present in a compound
Mass and charge of all sub atomic particles
Proton : mass=1 charge=+1
Neutron : mass=1 charge=0
Electron : mass=1/2000 charge=-1
First ionisation definition
The energy required to remove 1 mole electrons from 1 mole of gaseous particles to form 1 mole of gaseous 1+ atoms
Definition of isotopes
Atoms of an the same element with different number of neutrons
Define stereoisomers
When a compound has the same structural formula but a different arrangement in space
Define structural isomer
compound that has the same molecular formula but different structural formulae
Define nucleophile
An electron pair donor
Define homologous series
A family of compounds that have the same functional group and general formula with each successive member differing by CH2
Define functional group
A functional group of a molecule is the group of atoms that are responsible for its characteristics or reactions
Define general formula
It is an algebraic formula to describe any member of a family of compounds
What is an aromatic compound
For a compound to be aromatic it needs to contain a benzene ring
Define average bond enthalpy
the average energy required to break a bond, used as a measurement of the strength of a covalent bond. The average bond enthalpy is measured using a variety of molecules that contain a specific bond.
what is a covalent bond
a strong bond formed between 2 atoms due to the electrostatic attraction
between a shared pair of electrons and the atomic nuclei.
what is electro negativity
the ability of an atom to attract bonding electrons in a covalent bond. This
is often quantified using Pauling’s electronegativity values. Electronegativity increases towards F in the periodic table.
what is an ionic bond
electrostatic attraction between positive and negative ions
Enthalpy change of combution
the enthalpy change that takes place when one
mole of a substance is completely combusted.
Enthalpy change of formation
the enthalpy change that takes place when one mole of a compound is formed from its elements.
enthalpy change of neutralisation
the enthalpy change that takes place when one mole of water is formed from a neutralisation reaction.
Enthaly change of reaction
the enthalpy change that is associated with a particular chemical equation.
What is a hetrogeneous catalyst
a catalyst that is in a different state to the reactants (e.g. a solid catalyst with gaseous reactants
Homogeneous catalyst
a catalyst which is in the same state as the reactants.
What is Le Chateliwers Principle
: when a system in dynamic equilibrium is subject to change, the
position of equilibrium will shift to minimise the change. This principle is used to determine the effect of changing pressure, temperature or concentration on the position of equilibrium.
