Definitions Flashcards
Isotope
Atoms of the same element with different numbers of neutrons and therefore different masses
Relative isotopic mass
the mass of an atom of an isotope compared with 1/12th of the mass of an atom of carbon-12
Relative atomic mass
the wieghted mean mass of an atom of an element compared with 1/12th of the mass of an atom of carbon-12
Relative molecular mass
the weighted mean mass of a molecule compared with 1/12th of the mass of carbon-12
Relative formula mass
the weighted mean mass of a formula unit compared with 1/12th of the mass of carbon-12
1st ionisation energy
The amount of energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions
- Nuclear charge
- shielding
- atomic radius
- nuclear attraction
Oxidation
the loss of electrons ((formation of +ions))
an increase in the oxidation number (becomes more positive)
Reduction
the gain of electrons ((formations of -ions))
a decrease in oxidation number (becomes less positive)
Oxidising agent
a reagent that oxidises (takes electrons from) another species
Reducing agent
a reagent that reduces (gives electrons to) another speicies
Acid
an acid releases H+ ions in aqueous solution
an acid is a proton donor
weak acid / strong acid
A strong acid is fully dissociated in solution and a weak acid partially partially dissociated
Base
A proton acceptor
Alkali
A soluble base that releases OH- ions in water (/solution)
Salts
Salts are ionic compounds formed when the H+ ions in an acid are replaced by metal or ammonium ions
ionic bonding
electrostatic attraction between positive and negative ions
covalent bonding
The stong electrostatic attractions between a shared pair of electrons and the nuclei of bonded atoms
lone pair
a pair of electrons in the outer shell not used in the bonding
dative covalent bond
A shared pair of electrons in which the bonded pair is provided by one of the bonded atoms only
Average bond enthalpy
The average enthalpy that takes place when breaking by homolytic fission one mole of a given type of bond in molecules of a gaseous species
metallic bonding
The electrostatic attraction between positive metal ions and delocalised electrons
malleable
can easily be bent into different shapes
ductile
can be drawn into a wire
gaint ionic lattice
there is a continuous lattice arrangement of + and - ions in three dimensions
VSEPR
Valence shell electron pair repulsion
- electron pairs repel each other
- the repulsion between lone pair-lone pair>lone pair-bonded pair>bonded pair-bonded pair
Van der Waals
London forces and permanent dipole-dipole forces
London forces
The London dispersion force is the weakest intermolecular force. The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force is sometimes called an induced dipole-induced dipole attraction.
electronegativity
The ability of an atom to attract the bonding electrons in a covalent bond
Pauling value
defines the electronegativity of an element.
permanent dipole
a small charge difference that does not change across a bond with partial charges on the bonding atoms (the result of the bonded atoms having different electronegativities)
Polar covalent bond
A bond with a permanent dipole, with positive and negative partial charges on bonded atoms
Polar molecule
a molecule with an overall dipole hving taken into account any dipoles across bonds and the shape of the molecule and its structure
Hydrogen bond
a hydrogen bond is a strong dipole-dipole attraction between an electron difficient -NH, OH, HF on one molecule and a lone pair of electrons on a highly electronegative atom (N,O,F) on a different atom
Group (on periodic table)
A vertical column in the periodic table. Elements in a group have similar chemical properties and their atoms have the same number of outer shell electrons.
Period (on periodic table)
Horizontal rows in periodic table. Elements show trends in properties across the period
Subshell
A subshell is a group of the same type of orbital
Orbitals
Orbitals are regions of an atom containing up to two electrons with opposite spin
