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IB Chemistry Key Terms and Definitions (Unfinished)


Key terms for the 2009 syllabus onwards
Flashcards by Amina.M, updated more than 1 year ago
Created by Amina.M over 7 years ago

Resource summary

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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