BondingPeriodic Table Stuff&Redox

Bonding in Ionic Compounds

Ionic Bonds (Salts)

• Between a metal (usually) and a non-metal (usually). The metal gives up its electron to the non-metal. Giving up electrons turns the metal into a positively charged ion called a cation. Gaining the electrons turns the non-metal into a negtatively charged ion called an anion.

• The positive and negative charges attract each other. This is the ionic bond.

• Ionic compounds are crystals – the formula shows the ratio of the elements in the compound. It is known as a formula unit.

• They have high melting points.

• They are more likely to be soluble in water, the universal solvent.

• They are electrolytes.

CsClCaF2

Experienced chemists can often predict the structure that a given ionic species will adopt, based on the nature of the ions involved. This means that it is often possible to design ionic compounds having certain well-defined and desirable properties. As an example, chemists have been able to make high-temperature superconductors, such as the complicated ionic compound, YBa2Cu3O4. This solid conducts electricity with no resistance at all at low temperature (below ca. -100 degrees centigrade). Previous superconductors only had this property at much lower temperatures. The lack of resistance makes superconductors very useful in a number of technological applications - e.g. in designing high-speed trains that levitate above the track!The repeating structure of this solid is shown below (oxygen is large and red, barium large and yellow-ish, yttrium small and pink, and copper small and blue). Notice how many oxygen ions surround each barium and yttrium ion.

Covalent Bonds (Not-Salts)

• The electrons are shared between compounds. This allows each atom to have a full outer shell for stability.

• Covalent compounds are represented by true molecules. The formula represents how many of each atom there are in the molecule.

• 1 electron each shared is a single bond, 2 electrons each is a double bond and 3 electrons each is a triple bond.

• They have low melting points.• They don’t usually dissolve well in water.• They are not electrolytes.

Bonding in Covalent Compounds

Plot of region where e- sit. Not localized.

Bonding in Metals

Bonding in Covalent Compounds – VSEPR shapes

Bonding in Covalent Compounds – Polarities of Molecules

Bonding between Molecules – Intermolecular Bonding:

Hydrogen Bonding

Bonding between Molecules – Intermolecular Bonding:

Dipole - Dipole Bonding & Induced Dipole Bonding (london dispersion)

Collectively: van der waals forces

http://chemsite.lsrhs.net/bonding/LondonDispersion.html

Families/Groups; Periodic Law; Ionization energy & Electronegativity

Assigning Oxidation Numbers:

PO4-3 H2SO4

OIL RIG