1.3 bonding

• electronegativity is the strength of an atom to attract bonding pairs of electrons
• a polar bond is covalent bond where there is a separation of charge between one end and another
• first ionisation energy is the energy required to remove one mole of electrons from one mole of a gaseous atom of an element
• bond enthalpy is the energy needed to break a bond between atoms in their gaseous state measured in constant pressure
• covalent bonds are stronger than intermollecular forces
• ice is less dense than water because the bonds are very spaced out due to hydrogen bonding
• what is the shape and angle of a compound with 2 bonding pairs and no lone pair

  linear ( 180 ° )
• what is the shape name and angle of a compound with three bonding pairs and no lone pairs

  trigonal planar ( 120 °)
• what is the shape and angle of a compound with 4 bonding pairs and no lone electrons

  tetrahedral ( 109.5 ° )
• what is the shape and angle of a molecule with three bonding pairs and one lone pair of electrons

  trigonal pyramid (107 ° )
• what is the shape and angle of a compound with two bonding pairs and 2 lone pairs of electrons

  bent / v-shape ( 104.5 °)
• whats the shape and angle of a compound with five bonding pairs and no lone pairs of electrons

  trigonal bipyramidal ( 90 °  / 120 ° )
• what is the shape and angle of the compound with 6 bonding pairs and no lone pairs

  octahedral ( 90 ° )
• a dative covalent bond is when a shared pair of electrons comes from only one of the bonding atoms. this is also called co-ordinate bonding
• three thing that effect strength of metallic bonding

  1. amount of delocalised electrons (the more the stronger)
  2. size of ions (the smaller, the stronger the force)
  3. number of protons (more the stronger)
• How to explain shape

  1. State number of bonding pairs and lone pairs of electrons.
  2. State that electron pairs repel and try to get as far apart as possible (or to a position of minimum repulsion.)
  3. If there are no lone pairs state that the electron pairs repel equally
  4. If there are lone pairs of electrons, then state that lone pairs repel more than bonding pairs
  5. State actual shape and bond angle.
• electronegativity is the tendency of an atom to attract an electrons to itself in a covalent bond
• flourine, oxygen , nitrogen and chlorine are the most electronegative
• what are properties of metals?

  1. malleable
  2. ductile
  3. electrical conductors
  4. shiny
• explain the structure and bonding of metals?

  • contain metallic bonds
  • lattice of cations in a sea of delocalized electrons
• why do metals conduct electricity?

  free moving delocalized electrons that carry a charge
• what are the factors that effect the strength of metallic bonds and explain them?

  1. charge of cation - more positive charge means a stronger attraction between cations and delocalized electrons
  2. size of cation - smaller distance means smaller distance between cations and delocalized electron so stronger attraction
• what are pure metals?

  metals made of only one element
• what are alloys?

  Mixtures of two or more metals
• what are properties of ionic lattices?

  1. soluble
  2. high melting and boiling points
  3. brittle
  4. conduct electricity in molten or aqueous solutions
• what are lattice compounds?

  3d lattice structures made of anions and cations
• what are the shapes of the cations and anions in ionic lattices?

  perfect spheres
• common cations and their charges?

  • aluminium - 3+
  • silver - 1+
  • zinc - 2+
  • iron - 2+ or 3+
  • copper - 1+ or 2+
  • lead - 2+ or 4+
• how do represent charge?

  put the sign after the number (1+)
• how do u represent oxidation state?

  put the sign before the number ( +1 )
• how do you write ammonium ions?

  (NH4)+
• how do write these polyatomic ions?

  • hyrdrogencarbonate :(HCO)-
  • carbonate : (CO3)2-
  • nitrate : (NO3)-
  • phosphate : (PO4)3-
  • sulfate : (SO4)2-
  • manganate: (MnO4)2-
  • hydroxide : ( OH )-
• what are isoelectronic ions?

  ions that have the same amount of electrons
• why do ionic compounds shatter?

  when hit , like forces repel eachother
• what is covalent bonding?

  when only non-metals covalently bond together with a shared pair of electrons (uncharged)
• what happens when two pairs of electrons are shared together?

  a double bond
• put single bonds, double bonds and triple bonds in order of lengths and the in order of strength?

  • Length: Single bond > Double bond > Triple bond
  • Strength: Triple bond > Double bond > Single bond
• what is the general rule for determining the strength of covalent bonds?

  the shorter the length of the bond , the stronger the bond
• what is dative covalent bonding?

  when one atom contributes 2 electrons from its lone pair to the shared pair
• how do you represent a dative bond in a stick diagram?

  an arrow from the atom the lone pair comes from