Definitions Flashcards
Define the relative isotopic mass (2 marks)
Mass of an atom of that isotope
Relative to 1/12th mass of a C-12 atom
Define relative atomic mass (2 marks)
Mean mass of an atom
Relative to 1/12th mass of a C-12 atom
What is a covalent bond (2 marks)
electrostatic attraction between 2 nuclei
Between bonding pairs of electrons
Define periodicity in terms of atomic radius in P2 and P3 (3 marks)
- pattern of repeating physical and chemical properties with increasing atomic number
- atomic radii decreases across the period
- trends repeated in Period 3
Define ionic bonds (2 marks)
(Strong) Electrostatic attraction
Between oppositely charged ions
Define ionic bonds (2 marks)
(Strong) Electrostatic attraction
Between oppositely charged ions
In the mass spectrum of silicon, there is also a small peak at m/z = 14. Deduce the formula of this particle.
28 Si2+
What is the definition of electronegativity? (2 marks)
- Measure of an atom’s ability to attract a pair of e-s
- in a covalent bond
Define an acid.
A proton donor
What is an activation energy?
Minimum energy required for collision to be successful in a reaction
What is a mole?
Amount of substance that contains the same number of particles as the number of carbon atoms in exactly 12g of C12 isotope
Define autocatalysis
When a product of a reaction acts as a catalyst
What does Avogadro’s constant stand for
The number of 12C atoms in exactly 12g of 12C
Define a base
Proton acceptor
Define chiral molecules.
Molecules that contain a carbon atom attached to four different groups
Define a dimer
Molecule consists of 2 monomers to form a stable structure
Define electronegativity.
Ability for an atom to attract bonding pairs of electrons-s in a covalent bond
Define an electrophile.
A species attracted to a region of high electron density
(Lone pair acceptor)
Define enthalpy change.
Heat energy change at constant pressure of 100kPa
Define entropy
Measure of disorder
Define first electron affinity.
Enthalpy released when 1 mole of electrons is gained by 1 mole of gaseous atoms forming 1 mole of 1- gaseous ions
Define first ionisation energy.
Energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of 1+ ions under standard conditions
Define free radical
An atom having 1 unpaired electron
Define half equivalence point
The point which half the acid has been neutralised by the base or vice versa
Define half life
Time taken for the concentration of a reactant to decrease by half
Define Hess’s law
Enthalpy change for a reaction is independent of the route taken
Define heterolytic fission
Breaking of a covalent bond to form 2 different species
Define homolytic fission
Breaking of a covalent bond to form 2 identical species
What are the colours of methyl orange in each condition?
Acid - red
Neutral - orange
Alkaline - yellow
What are the colours of litmus in acidic and alkali conditions?
Acid - red
Alkali - blue
What are the colours of phenolphthalein in acidic and alkali conditions?
Acidic - colourless
Neutral - colourless
Alkaline - pink
Define ionic bond.
Electrostatic force of attraction between metal and non metal ions
Define isomers
Molecules with the same molecular formula but a different structural formula
Define isoelectric
Atoms, ions and molecules having the same number of electronic configuration
Define lattice enthalpy.
Energy released when 1 mole of ionic lattice is formed from its constituent gaseous ions under standard conditions
Define a ligand
Molecules that form dative covalent bonds/ coordinate bonds with a central (transition) metal ion
Define London forces.
The random, instantaneous movement of electrons in a molecule that causes an instantaneous and even distribution of electron density which uses a dipole and neighbouring molecules which then attract
Define mean bond enthalpy
Average enthalpy change when 1mole of covalent bond is broken from a range of compounds in the gas phase under standard conditions
Define monoprotic acid
An acid that releases 1 proton in aqueous solution
Define nucleophile
A species attracted to low electron density
Can donate lone pair of electrons to form covalent bond with an electron deficient atom (electrophile)
Define racemic mixture
A 50/50 mixture of 2 enantiomers
Define reforming
Using heat and pressure to convert unbranded fractions into branched molecules
Define standard electrode potential
EMF of electrochemical cellcomprised of half cell combined with a standard hydrogen electrode at 1atm, 1 Moldovan-3, 298K
Define standard enthalpy change of atomisation
Enthalpy required to make 1 mole of gaseous atoms from an element in its standard state under standard conditions
Define standard enthalpy change for combustion
Enthalpy change when 1 mole of substance is completely combusted under standard conditions
Define Standard enthalpy change of formation
Enthalpy change when 1 mole of a compound is formed from its constituent elements, with all elements in their standard states, under standard conditions
Define standard enthalpy change of hydration
Enthalpy released when 1 mole of gaseous ions is completely dissolved in an infinite volume of water
Define standard enthalpy of neutralisation
enthalpy change when 1 mole of water is formed from an acid-base reaction under standard conditions.
Define standard enthalpy of solution
enthalpy change when 1 mol of solid ionic compound completely dissolved in an infinite volume of water.
Define transition metals
d-block elements that form 1 or more stable ions which have incomplete d-subshells.
