chem

• as atomic number of alkali metals increases the first ionisation energy decreases
• covalent radius (atomic size) DECREASES across a period, and INCREASES down a group
• electronegativity INCREASES across a period, and DECREASES down a group
• metallic -> metallic lattice

  covalent -> network

  covalent -> molecular

  LDF -> monatomic
• LDF determine the melting point of covalent molecular bonding and monatomic bonding
• covalent molecular:

  • gas= H2, N2, O2, F2, Cl2
  • solid= P4, S8, C60 (fluorine)
• monatomic = noble gases (do not form bonds)
• Ionic bonding:

  • metal and non-metal
  • conduct as (l) or (aq) molten as ions are free to move
  • do not conduct as solid
  • soluble in water or polar solvents
  • STRONG BONDS
• metallic:

  • positive ions and delocalised electrons
  • STRONG BONDS
• covalent network:

  • VERY STRONG BONDS
  • NEVER CONDUCT, no free charged particles
  • graphite conducts as it has delocalised electrons
• Covalent molecular:

  • any compound thats (l) or (g) at room temperature
  • intramolecular bonds = strong (covalent bonds)
  • intermolecular forces = weak
• equal negativity = pure covelant
• big difference in electronegativity= ionic

  small difference in electronegativity= covalent
• London Dispersion Forces:

  • exists between all molecules + atoms
  • weakest intermolecular force
  • uneven electron distribution= temporary dipole and induced dipole
  • increased electrons = increased LDF
  • only force between monatomic elements
• Hydrogen Bonding:

  • large difference in electronegativity
  • STRONGEST intermolecular force
  • H bonded to N, O, F
  • soluble in polar solvents
• Permanent Dipole-Permanent Dipole:

  • soluble in polar solvents
  • exists between polar molecules
  • different electronegativities
  • delta negative on stronger element
• PD-PD:

  • linear= polar if connected to group 7
  • angular= polar if connected to group 6/7
  • trigonal pyramidal= polar is connected to group 5/7
  • tetrahedral= NON-POLAR if all connected elements are the same
• all hydrocarbons are non-polar and only have LDF between their molecules
• viscosity =thickness of liquid (how easily it flows)
• viscosity is impacted by:

  • molecular mass
  • molecular size
  • strength of intermolecular force
• strongest to weakest intermolecular force:

  • covalent network
  • metallic
  • ionic
  • Hydrogen bonding
  • Permanent Dipole-Permanent Dipole
  • LDF
• viscosity, melting point, and boiling point are impacted by type of intermolecular force
• LIKE DISSOLVES IN LIKE

  NON-POLAR DISSOLVES IN NON-POLAR

  POLAR DISSOLVES IN POLAR
• LDF= uneven distribution of electrons, causing temporary dipole-induced dipole
• LDF increase as size and number of electrons increase
• London Dispersion Forces exist between layers
• oxidation is loss of electrons

  reduction is gain of electrons
• redox reactions are when oxidations and reduction reactions both take place
• oxidising reactants are reduced and reducing reactants are oxidised
• reduction= copy databook

  oxidation= flip equation
• reducing agents donate electrons and oxidise themself

  oxidising agents accept electrons and reduce themself
• ignore spectator ions: ions that are not involved in the reaction, but are present in the solution
• oxidising + reducing agents can be elements, compounds or group ions
• reducing agents have low electronegativities as they easily lose electrons and be oxidised
• strongest reducing agents are in group 1 or top RHS of electrochemical series
• carbon monoxide is a reducing agent we use to produce metals
• oxidising agents are found in group 7 or the bottom LHS of the electrochemical series, they have a high electronegativity
• oxidising agents uses:

  • medical usage= killing fungi, bacteria, inactivating viruses
  • bleaching agent= clothes, hair (hydrogen peroxide)
• KMnO4 is used to treat athletes foot
• ion electron equations:

  • balance equation
  • add water to balance oxygen
  • add H+ to balance hydrogen
  • add electrons to balance charge (same side as H+)