Bonding

• three types of strong chemical bonds

  ionic, covalent and metallic
• ions

  charged particles, single or grouped atoms
• what ion does magnesium form and ionic equation

  In group 2, so looses 2 electrons so forms a Mg2+ ion

  Mg=Mg2+ + 2e-
• ionic bond

  oppositely charged ions are strongly attracted by electrostatic forces
• why do atoms become ions

  to get a full outer shell of electrons and a stable electronic structure
• For ionic bonding the particles are...

  oppositely charged ions.
• For covalent bonding the particles are...

  atoms which share pairs of electrons
• For metallic bonding the particles are...

  atoms which share delocalised electrons.
• When does ionic bonding occur

  formed from metals combined with non-metals
• Covalent bonding occurs in

  most non-metallic elements and in compounds of non-metals
• Metallic bonding occurs in

  elements and alloys.
• Description of what happens during ionic bonding

  When a metal atom reacts with a non-metal atom electrons in the outer shell of the metal atom are transferred. Metal atoms lose electrons to become positively charged ions. Non-metal atoms gain electrons to become negatively charged ions. The ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 have the electronic structure of a noble gas (Group 0).
• sodium chloride dot and cross

  
• sodium chloride diagram

  
• giant ionic description

  An ionic compound is a giant structure of ions. Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions. These forces act in all directions in the lattice, that is in a regular arrangement.

  
• what happens when a metal and non metal react (ionic)

  electrons are transferred from the outer shell of the metal to the non metal, metals become positive ions and non metals become negative ions
• what charged ions do

  group 1 atoms

  1+
• limitations of using dot and cross diagrams

  oversimplified

  
• limitations and pros of using ball and stick diagrams


  CON:

  the ions are actually close together, gives false image of bond direction

  PRO:

  regular pattern and ion arrangement and extends further
• limitations and pros of using two and three-dimensional diagrams


  CON:

  difficult to see the arrangement of ions- only outer layer

  PRO:

  relative sizes of atoms and regular pattern
• giant ionic diagram

  
• properties of giant ionic structures

  regular structure (giant ionic lattice)

  high melting/boiling points,

  do not conduct electricity when solid,

  do conduct electricity when molten

  form crystals with flat faces and straight edges
• why do ionic stuctures have a giant ionic lattice?

  strong electrostatic forces of attraction in all directions between oppositely charged ions
• why do giant ionic structures have high melting/boiling points?

  it takes a large amount of large of energy to break the many strong ionic bonds in the lattice
• why do giant ionic structures not conduct electricity when solid?

  the ions are in fixed positions and cannot flow to carry charge through the structure
• why do giant ionic structures conduct electricity when molten?

  the ions are free to move so charge can flow from place to place
• why do giant ionic structures form crystals with flat faces and straight edges?

  the ions are arranged in a highly ordered way in the 3D lattice
• how do you work out emperical formula when there is a dot and cross diagram

  count up how many atoms there are of each element, write this down and that is the empirical formulae
• how to work out empirical formulae with 3D diagram


  what ions are in the compound, work out what charges the ions will form, balance the charges of the ions so that the overall charge on the compound is zero
• Covalently bonded substances may consist of

  small molecules, large molecules, such as polymers and can have giant covalent structures,

  such as diamond and silicon dioxide
• bonding of ammonia (dot and cross diagram)

  
• dot and cross in covelent bonding limitations

  don't show relative sizes of atoms or how attoms are arranged in space

  
• what does the energy needed to change state depend on

  strength of the forces between the particles of the substance
• displayed formula convalent pros and cons

  shows how atoms are connected, dont show 3D strcuture or which aroms the electrons have coke from
• hydrogen bonding dot and cross

  
• hydrogen chloride bonding dot and cross

  
• methane bonding dot and cross

  
• small covalent bonding structure description

  A molecule is formed when a group of atoms are joined together by a shared pair of electrons called covalent bonds. Small molecules contain only a few atoms held together by strong covalent bonds. The intermolecular forces are weak, but as the small molecule gets bigger the weak forces between molecules increase.
• small covalent properties

  usually gases or liquids at room temp, do not conduct electricity, form crystals
• why are small covalent usually gases or liquids at room temp

  they have low melting/boiling points, because not much energy is needed to overcome their weak intermolecular forces