PHYSICAL CHEMISTRY

HideShow resource information
View mindmap
  • Atomic Structure
    • Chemical properties of elements  depend on atomic structure and arrangement of electrons around nucleus
    • Physical Chemistry
      • Amount of substance
        • relative atomic mass and relative molecular mass
          • relative ATOMIC mass (Ar)
            • carbon- 12
              • is used as a baseline for relative atoimic mass - Mass spectrometer means  we able to measure masses of individuals istopes accuratley
            • reative atomic mass is define as ................. Ar = average mass of an atom / 1/12 of 1 atom of C-12
          • relative FORUMLA mass is used for ionic compounds because they don't exist as molecules. but have same symbol ( Mr)
          • relative    MOCULAR  mass (Mr)
            • defined as ......         Mr = average mass of an entity / 1/12 of 1 atom of C-12
            • Carbon-12
              • compare mass of a molecule with that of an atom of Carbon -12
        • The mole and Avogradro constant
          • Avogradro constant
            • defined as the number of atoms in 12g of Carbon-12
            • actual number of atoms in 1g of hydrogen is huge and usually written as 6.022 x 10^23
          • The mole
            • the amount of substance that contains 6.022 x 10^23 particles
            • to find moles
              • mass/ Mr
              • concentration x volume / 1000
              • to find concentration
                • number of moles / volume
        • ideal gas equation
          • PV = nRT
            • n= moles
            • V= volume
            • R= gas constant
            • P= pressure
            • T = temperature
        • Empirical formula
          • is the simplest whole number ration of atoms of each element in a compound
          • to find empirical formula
            • 1. find masses of elements present            2. work out number of moles                3. convert No. of moles into a whole number ratio
          • molecular formula gives the actual number of atoms of each element of the compound
            • Mr/ mass of empirical  formula
        • Blanced eqations and assoiciate equations
          • balanced equations
            • Make sure there are the same number reactants and products on each side
          • ionic equations
            • 1.write out equation         2. note which ions are present          3. rewrite equation with ions               4. get rid of that appear on both sides - these arte spectator ions
          • Atom economy
            • mass of desired product / total mass of reactants x 100
          • percentage yield
            • the number of moles of a specified product / theoretical maxium number of moles of the product x 100
        • Chemists use amount of a subatnce in moles because one mole of a subatnce always contains same number of entiites of the substance
    • Arrangement  of electrons in orbritals linked to the way in which elemnets are orgsnised in periodic table
    • Measure mass of atoms using mass spectrometer
    • Fundamental particles
      • Protons
        • Charge = +1
        • Mass = 1
      • Electrons
        • Charge = -1
        • Mass = very small
      • Neutrons
        • Charge= no charge
        • Mass = 1
      • Carbon - 12
        • Chosen as its mass  per nucleon is around average
          • Therefore an atomic mass unit is defined as 1/12th of the mass of one atom of Carbon-12
    • Mass number and isotopes
      • Atom is named after number of protons in nucleus
      • The number of protons in the nucleus of an atom is called the ATOMIC NUMBER
        • It has the symbol Z
      • The MASS NUMBER is the sum of protons and neutons in neuclus of atom
        • it has the symbol A
      • ISOTOPES  are atoms with the same atomic number but different mass numbers
        • They therefore differ in relative atomic  mass but have same chemical properties
      • Time Of Flight (TOF) Mass Spectrometer
        • it can be used to:                     find the abundance and mass of each isotope in an element allowing us to determine relative atomice mass...
          • .....And find the relative molecular mass of substances made from molecules
        • stage 1
          • Ionisation
            • Electronspray
              • sample dissolved in a volatile solvent. injected into mass spectrometer
                • Particles are ionised by gaining a proton from electron spray
              • Its used for   substances with higher molecular mass
        • stage 2
          • Acceleration
            • Positive ions are then accelerated using electric field to give them all the same kinetic energy
              • Lighter particles have a faster velocity and heavier particle have a slower  velocity
        • Stage 3
          • Flight  tube ( ion drift )
            • Ions travel through hole in the negatively charged plate into a ube
              • TOF of each paricle depends on its velocity and therefore mass
        • Stage 4
          • Detection
            • + Ions hit - charged electric plate. the + ions are discharged by gaining electrons from the plate
              • This generates a movement of electrons and an electric current is measured
                • it can be used to identify elements and determine relative molecular mass
        • Gives accurate information about relative isotopic mass and also the relative abundance of isotopes
    • electron configuration
      • FIRST IONISATION ENERGY  Is the energy required to remove one mole of the most loosely held electrons from one mole of gaseous atoms to produce 1 mole of gaseous ions each with a charge of +1
      • The maximum No. of electrons in each shell are:
        • Shell 1 :
        • shell 2:
        • shell 3:
        • Sub shells
          • D: 10 electrons
          • P: 6 electrons
          • F: 14 electrons
          • S: 2 electrons
        • Orbitals
          • S orbital
          • P orbitals
      • ionisation energies
        • SECOND IONISATION ENERGY bigger than 1st - when 1st electron is removed a + ion forms - increases attraction between remaining electrons so energy reuired to remove nexdt electron is larger
  • Chosen as its mass  per nucleon is around average
    • Therefore an atomic mass unit is defined as 1/12th of the mass of one atom of Carbon-12

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all ATOMIC STRUCTURE resources »