Chemistry Unit 1 Flashcards

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A-Levels Chemistry (Unit 1 - Electronic Structure and the Periodic Table) Flashcards on Chemistry Unit 1 Flashcards, created by snowred-orange on 05/05/2013.
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Question Answer
Amphoteric oxides exhibit both acidic and basic properties e.g. aluminium oxide (Al2O3) + H2O and BeO
Covalent Chlorides which form white fumes of HCl when in water? AlCl3 (aluminium chloride), SiCl4 (silicon chloride), PCl3 (phosphorus chloride), SCl2 (sulphur chloride)
Hydrides NaH - strong alkaline MgH2 - alkaline SiH4 - neutral H2S - weak acidic HCl - strong acid
Electrolysis of hydrides electrolysis of molten hydrides produces Hydrogen gas at +VE electrode
Oxidation States rules : #Uncombined element = 0 #Ions have O-number of charge #Fluorine always = -1 #Hydrogen mostly = +1 #Oxygen usually = -2
Ligands negative ions or uncharged molecules with one or more lone pairs of electrons. & electron donors, forming dative covalent bonds
Naming complexes e.g. [Fe(CN)6]2- -ligands first, alphabetical order:(ammine, aqua, cyano, chloro) - If complex -ve, ion name ends in 'ate' (ferrate, cuprate) e.g. hexacyanoferrate (II) ion
Degenerate of equal energy (degenerate E levels)
Colours of light
Why do metal compounds absorb light? e-'s in lower E d-orbitals absorb E and move to higher E orbitals. If energy in d-d transitions corresponds to colour in visible spectrum, we see complementary colour
Catalysts Lower the activation energy --> alternative reaction pathway. Aren't used up. Homogenous, heterogenous (same/different states to reactants)
Ground state The lowest E level an electron can be in.
Lyman Series within UV light spectrum e-'s fall to n=1 energy level
Balmer series within Visible light spectrum excited electron falls to energy level of n=2
Principal Quantum number n corresponds to the electron shell e.g. n=2
Heisenberg's Uncertainty Principle "impossible to define with absolute precision, the position & momentum of an electron simultaneously"
Pauli Exclusion Principle atomic orbitals hold a max of 2 electrons with opposite spins. e.g. no two electrons in an atom can have the same four quantum numbers
S orbital spherical like a ball max no. of electrons = 2
P orbital dumbbell shaped px, py or pz aligned along one of the 3 perpendicular axes'
D orbitals degenerate with each other higher energies then s and p orbitals in same shell
Aufbau Principle Electrons fill orbitals in order of inc. E lowest subshell filled first
Hund's Rule electrons fill each degenerate orbital singly with parallel spins before pairing occurs
Electronic arrangements show only no. of electrons in each shell
Electronic configurations show the subshell that electrons are in
Atomic Emission Spectra colour spectrum + black lines
Electronegativity differences (Δ EN ) use to predict type of bond: same EN = non-polar covalent ΔEN is 0.8ish = polar covalent ΔEN is 3.2+ = ionic
Lewis Dot Cross diagrams or electron dot diagrams
Resonance Structures
Linear Two bonding e- pairs e.g. BeCl2
Trigonal 3 bonding pairs (flat triangle shape) e.g. BCl3
Tetrahedral 4 bonding pairs (pyramid shape, triangle bottom) e.g. CH4
Trigonal Bipyramid 5 bonding pairs (3D diamond shape) e.g. PCl5
Octahedral 6 bonding pairs (90 degree angle between each atom) e.g. SF6
Ionic lattice structure types common : NaCl structure 6:6 co-ordination rarer : CsCl structure 8:8 co-ordination
Superconductors zero electrical resistance at temperatures close to absolute zero (0K or -273 degrees)
Semiconductors higher conductivity than covalent, lower conductivity than metals. as temp increases, conductivity increases.
N-type semiconductor N-type = negative electrons carry charge e.g. silicon doped with arsenic or phosphorus
P-type semiconductor positive holes main current carrier e.g. silicon doped with boron/aluminium
Wavelength distance between adjacent crest in a wave -lambda
Frequency number of wavelengths passing a fixed point in one second v = symbol
Unit of wavelength nanometres - nm - (1x10-9)
Unit of frequency Hertz - Hz
Unit and symbol of Velocity symbol = c (ms-1)
Properties of IR light long wavelength + low frequency
Properties of UV light Short wavelength + High frequency
Planck's constant 6.63 x 10 - 34 Js
Avogadro's constant 6.02 x 10^23 mol-1
Emission Spectra Black spectrum + coloured lines Lines correspond to E given out when excited electron moves to a lower E level.
Excited state when an electron absorbs the appropriate quantity of E to move from ground state to higher E level.
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