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IB Chemistry Key Terms and Definitions (Unfinished)
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- 1First Ionization EnergyThe minimum energy needed to remove the most loosely held electron from 1 mol of gaseous atoms
- 2Successive Ionization EnergyThe energy needed to remove a successive electron from 1 mole of gaseous ions
- 3Heisenberg Uncertainty PrincipleIt is impossible to pinpoint accurately the position and momentum of an electron
- 4Aufbau PrincipleElectrons are first placed in the lowest level and orbital
- 5Pauli Exclusion PrincipleTwo electrons can only occupy the same atomic orbital if they spin in opposite directions as this reduces repulsion
- 6Hund's RuleElectrons are first spread out over the degenerate orbitals then paired up
- 7IsotopeAn atom of the same element with the same no.protons but a different no.neutrons
- 8RadioisotopesIsotopes that are radioactive, dangerous to living things because the radiation can change the structure of DNA within the genes of cells
- 9Mass SpectrometryA technique used to obtain: no.isotopes of an element, relative isotopic mass of each isotope and relative abundance of each isotope
- 10VaporizationSubstance is heated to change it into vapour so that each atom is free and independent
- 11IonizationNeutral atoms are converted to cations by bombarding them with high speed electrons
- 12AccelerationCations are accelerated by an electric field
- 13DeflectionCations are deflected by a magnetic field moving them into a curved path; amount of deflection depends on mass/charge ratio
- 14DetectionCations strike the detector screen, which records the ion according to its mass by an electric current
- 15Line Emission SpectrumA pattern of thin discrete lines of a different colour, each which corresponds to a specific frequency
- 16Continuous SpectrumA spectrum of radiation that consists of a continuous range of frequencies and colours
- 17GroupVertical column; shows same no.valence electrons
- 18Periodhorizontal row; indicates energy shell being filled
- 19Electronegativitythe ability for an atom to attract a bonding pair of electrons; measured relative to a flourine atom
- 20AmphotericHaving the ability to neutralise both acids and bases
- 21Transition ElementA 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
- 22Complex / Complex iona central metal ion surrounded by a number of other molecules or ion; usually formed when transition metals are dissolved in water or become hydrated
- 23LigandA molecule or anion which contains a lone pair of electrons which are used to form dative bonds with the central ion in a complex
- 24Coordination NumberThe number of ligands that are attached to a metal ion
- 25CatalystsA substance that provides an alternative pathway for a reaction to occur by lowering the activation energy without being used up
- 26Heterogeneous Catalysiscatalyst in a different phase from the reactants and doesn't take part in the reaction
- 27Homogeneous CatalysisCatalyst in the same phase as the reactants and can take part in the reaction
- 28Ionic BondingThe electrostatic attraction between oppositely charged ion
- 29Giant ionic latticeA regular 3D-arrangement of anions and cations held together by strong ionic bonds
- 30Covalent BondingThe sharing of electrons as a result of overlapping of two half-filled atomic orbitals of two atoms
- 31Dative BondsThe formation of a bond by sharing of a pair of electrons both of which are donated by the same atom
- 32Bond lengthThe distance between two covalently bonded nuclei
- 33Bond strength/enthalpythe amount of energy needed to break 1 mole of bonds from molecules in their gaseous states
- 34Polar Bondsbonding pairs of electrons are attracted unequally by both atoms
- 35Symmetricalthe centre of the negative charge and the centre of the positive charge of a molecule are not super-imposable
- 36Dipole MomentA separation of charge as caused by a polar bond
- 37VSEPR Theory1) 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 - 38Allotropesdifferent physical forms of the same element
- 39Intermolecular Forcesforce of attraction between molecules in which atoms are covalently bonded
- 40Van der Waal's Forcesweak forces between non-polar molecules and monatomic molecules of the noble gas
- 41dipole-dipole attractionattraction between permanent dipoles/polar molecules
- 42instantaneous dipoleattraction between permanent dipoles or polar molecules
- 43induced dipolesa non-polar molecule can become polarised if it is near a permanent or instantaneous dipole
- 44Hydrogen bondingstrong attraction between highly positive hydrogen atoms and either Oxygen, Fluorine or Nitrogen
- 45Metallic Bondingthe attraction between a sea of delocalized electrons and the lattice of cations
- 46Metallic Structurelattice formed by strong attraction between metal ions and free electrons
- 47Giant covalent structurelattice held together by very strong covalent bonds between atoms
- 48simple molecular structurelattice of molecules held together between metal ions and free electrons
- 49sigma bondsformed as a result of the 'head on' overlap of two atomic orbitals along the intermolecular axis
- 50pie bondsformed as a result of the 'sideways' overlap of two parallel p unhybridized orbitals
- 51Hybridizationthe 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
- 52Delocalizationsharing of pi electrons as a result of sideways overlapping of unhybridized p orbitals of three or more atoms, creating a large continuous molecular orbital
- 53Resonance structures
- 54Kinetic Energyenergy by virtue of the motion of a system
- 55Potential energythe energy stored in a system
- 56systemall the chemicals involved in a chemical reaction
- 57surroundingsanything else that is not the reacting mixture
Información
- Descripción
- Key terms for the 2009 syllabus onwards
- Creado por
- Amina.M
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