Definitions Flashcards
Define relative atomic mass
the weighted mean mass of an atom of an element relative to 1/12 of the mass of an atom of 12C
Define relative isotopic mass
the mass of an atom of an isotope compared to 1/12 the mass of an atom of 12C
Define 1st ionisation energy
the energy required to remove 1 electron from each atom in 1 mole of a gaseous element to form 1 mole of gaseous 1+ ions
Define nuclear attraction
the attractive force that the outer shell of electrons experiences from the nucleus
Define shielding
the repulsion between electrons in inner shells
Define an orbital
a region within an atom that can hold up to 2 electrons with opposite spin
Define a subshell
a group of the same type of atomic orbitals within a shell
Define electronegativity
the ability of an atom to attract the bonding pair of electrons in a covalent bond
Define a hydrogen bond
the attraction between the d+ H atom on 1 molecule and the lone pair of electrons on the d- Fluorine, Nitrogen or Oxygen on a different molecule
What is the equation for finding the number of particles in a substance?
number of particles = ( mass (g) / molar mass (g/mol) ) x 6.02x10^23
(number of particles = moles x 6.02x10^23)
What is the equation for atom economy?
atom economy = ( sum of molar masses of desired products / sum of molar masses of all products ) x 100
What is the equation for percentage yield?
percentage yield = (actual yield / theoretical yield ) x100
What is the ideal gas equation? What are the units?
pV = nRT
pressure(Pa) x volume(m^3) = number of moles x gas constant x temperature(K)
What is the gas constant?
8.314 J/mol/K
How do you convert celsius to kelvin?
add 273 degrees
What is Avagadro’s constant?
6.02 x10^23
Define molecular formula
the exact number of atoms of each element present in a molecule
Define empirical formula
the simplest whole number ratio of atoms in a molecule
Define homologous series
a series of compounds with the same functional group, with each successive member differing by a CH2 group, and having the same general formula
Define homolytic fission
when a covalent bond breaks and one electron from the bonding pair is given to each atom previously involved in the bond to create 2 free radicals
Define a radical
an atom with a single unpaired electron that is very reactive
Define heterolytic fission
when a covalent bond breaks and one atom takes both of the bonding pair of electrons to become a negative ion, leaving the other atom as a positive ion
Define a sigma bond
the overlapping of 2 orbitals directly in the plane of the 2 atoms
Define hydrolysis
using water to break chemical bonds
opposite of condensation
Define standard enthalpy of combustion
the enthalpy change when 1 mole of a substance is completely combusted with oxygen under standard conditions with all products and reactants in their standard states
Define standard enthalpy of neutralisation
the enthalpy change when 1 mole of water is produced by the reaction of an acid and a base, under standard conditions
Define standard enthalpy of formation
the enthalpy change when 1 mole of a substance is formed from its elements under standard conditions
Define standard enthalpy of atomisation
the enthalpy change when 1 mole of gaseous atoms of a substance are formed from the substance in its standard state, under standard conditions
What are standard conditions?
298 degrees K and 100kPa
Define enthalpy change of reaction
the enthalpy change accompanying a reaction in the molar quantities shown under standard conditions, with reactants and products in their standard states
Define first electron affinity
the enthalpy change when each atom in one mole of gaseous atoms gains one electron to form one mole of gaseous 1- ions
Define second electron affinity
enthalpy change when each ion in one mole of gaseous 1- ions gains one electron to form one mole of gaseous 2- ions.
Define hydration enthalpy
enthalpy change when one mole of gaseous ions becomes hydrated (dissolved in water) (g) => (aq)
Define enthalpy of solution
the enthalpy change when one mole of an ionic solid is dissolved
in an amount of water large enough so that the dissolved ions are well separated and do not interact with each other
Define bond dissociation enthalpy
the enthalpy change when one mole of covalent bonds is broken in the gaseous state
Define lattice enthalpy of formation
the enthalpy change when one mole of a solid ionic compound is formed from its constituent ions in the gas phase (g) => (s)
Define lattice enthalpy of dissociation
the enthalpy change when one mole of a solid ionic compound is broken up into its constituent ions in the gas phase (s) => (g)
Define enthalpy of vaporisation
enthalpy change when one mole of liquid is turned into a gas (l) => (g)
Define enthalpy of fusion ?
the enthalpy change when one mole of a solid is turned into a liquid (s) => (l)
Define enthalpy of neutralisation
the enthalpy change when 1 mole of water is formed in a reaction between an acid and an alkali under standard conditions
Define standard electrode potential
the electromotive force of a half cell compared to the standard hydrogen electrode measured at 298K, solution conc. 1 moldm-3 and at a pressure of 100kPa
Define a condensation polymer
a long chain molecule formed by the joining together of monomers with the loss of a small molecule (H2O or HCl)
