C3 bonding

• ionic bonding occurs between metals and non-metals
• in ionic bonding, electrons are transferred from metal atoms to non-metal atoms to achieve full outer shells, forming positive and negative ions
• in ionic compounds, oppositely charged ions are attracted to each other by electrostatic forces, forming a giant ionic lattice, this is a 3D structure
• the formula of a sulfate ion is SO4(2-)

  the formula of a hydroxide ion is OH(-)

  the formula of a nitrate ion is NO3(-)

  the formula of a carbonate ion is CO3(2-)

  the formula of an ammonium ion is NH4(+)
• covalent bonding occurs between non-metals and other non-metals
• in covalent bonding, electrons are shared between the two outer shells to achieve full outer shells
• multiple electron pairs can be shared to produce multiple covalent bonds
• coordinate bonding is a form of covalent bonding where both electrons in the shared pair are supplied from a single atom
• coordinate bonds react in the exact same way as covalent bonds
• in a diagram, covalent bonds are shown with a line, coordinate bonds are shown with an arrow
• metallic bonding occurs between metals and other metals
• in metallic bonding, the greater the charge of the positive ion, the stronger the electrostatic forces as more electrons are released into the sea
• in metallic bonding, a sea of delocalised electrons surrounds a lattice of positive ions, held together by strong electrostatic forces of attraction between negative electrons and positive ions
• the larger the positive ion, the weaker the electrostatic forces as the nucleus is further from the delocalised electrons
• electronegativity is the ability of an atom to attract the electron density in a bond, the bonding pair of electrons, towards itself
• electronegativity increases going up a group because atoms get smaller, and there is less shielding
• electronegativity increases going across a period because nuclear charge increases, atoms gets smaller, but number of energy levels is constant
• the most electronegative atom is F, then O, N, Cl
• the negative charge in a covalent bond is not distributed evenly, unless both atoms are of the same element, as different atoms have different electronegativities
• covalent bonds are polar, and increase in polarity as the difference in electrnoegativity of the atoms increases
• there are 3 types of intermolecular forces:

  • van der Waals
  • dipole-dipole
  • hydrogen bonding
• van der Waals forces act between all atoms and molecules
• van der Waals forces are the weakest type of intermolecular force
• as Mr increases, strength of van der Waals forces increases, as there are more electrons
• compounds with unbranched molecules have stronger van der Waals than compounds with branched molecules because the straight molecules can pack closer together
• dipole-dipole forces act between molecules with a polar bond
• in a polar bond, the delta-positive and delta-negative regions attract each other, holding the molecules together
• hydrogen bonds form between hydrogen atoms and either fluorine, oxygen, or nitrogen atoms
• hydrogen bonds are the strongest type of intermolecular force
• to form a hydrogen bond, the lone pair on the fluorine/oxygen/nitrogen of one molecule is attracted to the hydrogen of another molecule
• to draw hydrogen bonds:

  • show the bond as a dotted line
  • it must be 180 degrees
  • label the delta-positive and delta-negative regions
• molecules form different shapes depending on the number of bonding pairs and lone pairs they have, and the shapes have specific angles
• 2BP and 0LP:

  name = linear

  angle = 180
• 3BP and 0LP:

  • name = trigonal planar
  • angle = 120
• 4BP and 0LP:

  name = tetrahedral

  angle = 109
• 5BP and 0LP:

  • name = trigonal bipyramidal
  • angles = 120 and 90
• 6BP and 0LP:

  • name = octahedral
  • angle = 90
• 2BP and 1LP:

  • name = bent
  • angle = <120
• 3BP and 1LP:

  • name = trigonal pyramidal
  • angle = 107
• 4BP and 1LP:

  • name = seesaw
  • angles = <120 and <90