Bonding: Bonds & Electronegativity

Types of Bonds:
        -There are three main types of bonds
           1)Ionic Bonds
                  - e- are tranferred from metal to nonmetal
           2) Covalent Bonds
                  -e- are shared between non-metals
           3) Metallic Bond 
                  - holds pure metals together by electrostatic attraction
Electronegativity:
        -Electronegativy is a measure of an atom's attraction for electrons in a bond.
            -Atoms with greater electronegativity attract e- more.
            -Polar covalent bonds form from an unequal sharing of e- while non polar covalent bonds form from equal sharing of e-.
Bonds:
        -The type of bond formed can be predicted by looking at the difference in electronegativity of the elements.
en > 1.7= ionic bonds
en<1.7= Polar covalent bonds
en=0= Non-polar covalent bonds
http://www.youtube.com/watch?v=R-zbdQxAhD4
http://www.youtube.com/watch?v=pLuXJQ_uHdE

-Candace Chan

Solution Stoichiometry

Solutions:

Solution are homogenous mixtures composed of a solute and a solvent.
     - Solute is the chemical present in lesser amount (whatever is dissolved)
     - Solvent is the chemical present in the greater amount.(whatever does the dissolving)
Chemicals dissolved in water are aqueous.
     -NaCl(aq)Molarity:

Molarity:

Concentration can be expressed in many different ways
    - Ex: g/L, mL/L, % by volume, % by mass, mol/L
The most common (in Chemistry 11&12) is mol/L(also can be M) which is also called Molarity.
    - mol/L= M
    -[HCl] = concentration of HCl

Examples:

What is the concentration of Copper(II) Chloride solution made from 0.50 mol of CuCl2 dissolved into 250 mL of water?

- Remember how to calculate Molarity. It's mol/L. You have moles and mL. Convert the mL to L by dividing by 1000 and divide the moles and litres together.

0.50 mol x   1      = 2.0 mol/L or 2.0 M
                 0.25L

A solution of Pb(NO3)2 has a concentration of 0.450 M. How many moles of solute are contained in 250 mL?

- To do this question, you must reverse the equation.

0.330 mol   x 0.250 L   = 0.0825 mol
            L            1

http://www.iun.edu/~cpanhd/C101webnotes/aqueoussolns/solstoic.html
http://www.chemcollective.org/stoich/solution_stoi.php
http://www.youtube.com/watch?v=uiEc5LcsGIg

-Candace