Question | Answer |
First Ionization Energy | The minimum energy needed to remove the most loosely held electron from 1 mol of gaseous atoms |
Successive Ionization Energy | The energy needed to remove a successive electron from 1 mole of gaseous ions |
Heisenberg Uncertainty Principle | It is impossible to pinpoint accurately the position and momentum of an electron |
Aufbau Principle | Electrons are first placed in the lowest level and orbital |
Pauli Exclusion Principle | Two electrons can only occupy the same atomic orbital if they spin in opposite directions as this reduces repulsion |
Hund's Rule | Electrons are first spread out over the degenerate orbitals then paired up |
Isotope | An atom of the same element with the same no.protons but a different no.neutrons |
Radioisotopes | Isotopes that are radioactive, dangerous to living things because the radiation can change the structure of DNA within the genes of cells |
Mass Spectrometry | A technique used to obtain: no.isotopes of an element, relative isotopic mass of each isotope and relative abundance of each isotope |
Vaporization | Substance is heated to change it into vapour so that each atom is free and independent |
Ionization | Neutral atoms are converted to cations by bombarding them with high speed electrons |
Acceleration | Cations are accelerated by an electric field |
Deflection | Cations are deflected by a magnetic field moving them into a curved path; amount of deflection depends on mass/charge ratio |
Detection | Cations strike the detector screen, which records the ion according to its mass by an electric current |
Line Emission Spectrum | A pattern of thin discrete lines of a different colour, each which corresponds to a specific frequency |
Continuous Spectrum | A spectrum of radiation that consists of a continuous range of frequencies and colours |
Group | Vertical column; shows same no.valence electrons |
Period | horizontal row; indicates energy shell being filled |
Electronegativity | the ability for an atom to attract a bonding pair of electrons; measured relative to a flourine atom |
Amphoteric | Having the ability to neutralise both acids and bases |
Transition Element | A d-block element that forms at least one stable ion that has a partially filled d sub-level. Characteristics include: variable oxidation states, complex ion formation, coloured compounds and catalytic properties |
Complex / Complex ion | a central metal ion surrounded by a number of other molecules or ion; usually formed when transition metals are dissolved in water or become hydrated |
Ligand | A molecule or anion which contains a lone pair of electrons which are used to form dative bonds with the central ion in a complex |
Coordination Number | The number of ligands that are attached to a metal ion |
Catalysts | A substance that provides an alternative pathway for a reaction to occur by lowering the activation energy without being used up |
Heterogeneous Catalysis | catalyst in a different phase from the reactants and doesn't take part in the reaction |
Homogeneous Catalysis | Catalyst in the same phase as the reactants and can take part in the reaction |
Ionic Bonding | The electrostatic attraction between oppositely charged ion |
Giant ionic lattice | A regular 3D-arrangement of anions and cations held together by strong ionic bonds |
Covalent Bonding | The sharing of electrons as a result of overlapping of two half-filled atomic orbitals of two atoms |
Dative Bonds | The formation of a bond by sharing of a pair of electrons both of which are donated by the same atom |
Bond length | The distance between two covalently bonded nuclei |
Bond strength/enthalpy | the amount of energy needed to break 1 mole of bonds from molecules in their gaseous states |
Polar Bonds | bonding pairs of electrons are attracted unequally by both atoms |
Symmetrical | the centre of the negative charge and the centre of the positive charge of a molecule are not super-imposable |
Dipole Moment | A separation of charge as caused by a polar bond |
VSEPR Theory | 1) Negative charged centres arrange themselves in such a way as to reduce the amount of repulsion 2) Double and triple bonds count as 1 negative charge centre 3) Bonding pairs and non-bonding pairs arrange themselves to be as far apart from each other as possible to reduce repulsion 4) Repulsion: 2 lone pairs > 1 lone pair and 1 bonding pair> 2 bonding pairs |
Allotropes | different physical forms of the same element |
Intermolecular Forces | force of attraction between molecules in which atoms are covalently bonded |
Van der Waal's Forces | weak forces between non-polar molecules and monatomic molecules of the noble gas |
dipole-dipole attraction | attraction between permanent dipoles/polar molecules |
instantaneous dipole | attraction between permanent dipoles or polar molecules |
induced dipoles | a non-polar molecule can become polarised if it is near a permanent or instantaneous dipole |
Hydrogen bonding | strong attraction between highly positive hydrogen atoms and either Oxygen, Fluorine or Nitrogen |
Metallic Bonding | the attraction between a sea of delocalized electrons and the lattice of cations |
Metallic Structure | lattice formed by strong attraction between metal ions and free electrons |
Giant covalent structure | lattice held together by very strong covalent bonds between atoms |
simple molecular structure | lattice of molecules held together between metal ions and free electrons |
sigma bonds | formed as a result of the 'head on' overlap of two atomic orbitals along the intermolecular axis |
pie bonds | formed as a result of the 'sideways' overlap of two parallel p unhybridized orbitals |
Hybridization | the mixing of a number of a number of non-equivalent but similar atomic orbitals to form the same number of degenerate atomic orbitals for bonding |
Delocalization | sharing of pi electrons as a result of sideways overlapping of unhybridized p orbitals of three or more atoms, creating a large continuous molecular orbital |
Resonance structures | |
Kinetic Energy | energy by virtue of the motion of a system |
Potential energy | the energy stored in a system |
system | all the chemicals involved in a chemical reaction |
surroundings | anything else that is not the reacting mixture |
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