Bonding Periodic 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.

CsCl CaF 2

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, YBa 2 Cu 3 O 4. This solid conducts electricity with no resistance at all at low temperature (below ca 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

Families/Groups; Periodic Law; Ionization energy & Electronegativity

Assigning Oxidation Numbers: PO 4 -3 H 2 SO 4

OIL RIG