April 26, 2011 - Halides (Angelo)

Halides:
- Group 7 elements (Flurine, Chlorine, Bromine, Idodine) can bind to a hydrocarbon chain
- Naming follows standard rules with halides using floro-, chloro-, bromo- and iodo-

EXAMPLES:


1. Name the following compound.


Answer: 2 3 Dibromo Pentane

2. Draw the following compound: 1 Chloro 3 Iodo Propane
Answer:

April 26, 2011 - Alcohols (Angelo)

Alcohols:
- an alcohol is a hydrocarbon with a -OH bonded to it
- some naming rules apply but the parent chain ending with -ol
- The following compound is ethanol...


Multiple -OH:
- if a compound has more than one -OH group, number both and add -dio, -trio, et cetera.

EXAMPLES:


1. Name the following compound.


Answer: 1 Propanol

2. Name the following compound.
 

Answer: 1, 3 Propanediol

Alkenes & Alkynes (double & triple bonds)- brian

- carbon can form double & triple bonds with carbon atoms

- when multiple bonds form fewer hydrogen's are attached to the carbon atom

- naming rules are almost the same as with alkanes
-the position of the double/triple bonds always has the lowest number and is put in front of the parent chain

- double bonds(Alkenes) end in ENE

- triple bonds(Alkynes) end in YNE

Example:

Trans & Cis butene
- if two adjacent carbons are bonded by a double bond and have side chains on them two possible compounds are possible
 

          














Multiple double bonds
- more than one double bond can exist in a molecule

- use the same multipliers inside the parent chain

Example:

March 31,11 Polar Molecules

Polar Molecules:-Polar molecules have an overall charge separation
-Unsymmetrical molecules are usually polar
-Molecular dipoles are the result of unequal sharing of electrons in a molecule

Predicting Polarity:
-If a molecule is symmetrical the pull of e is usually balanced
-Molecules can be unsymmetrical in two ways
1)different atoms
2)different number of atoms

http://www.youtube.com/watch?v=LKAjTE7B2x0

March 28, 2011 - Bonding, Bonds and Electronegativity (Angelo)

Types of Bonds:
- there are three main types of bonds
     1. Ionic (metal  -  non-metal)
          - electrons (will now be abbreviated to e.) are transferred from metal to non-metal
     2. Covalent (non-metal  -  non-metal)
          - e. are shared between non-metals
     3. Metallic (metal)
          - holds pure metals together by electrostatic attraction

Electronegativity:
- electronegativity (will now be abbreviated to "en.") is a measurement of an atom's attraction for e. in a bond (NOTE: there are NO UNITS for electronegativity)
     - Fluorine = 4.0
     - Chlorine = 3.0
     - Cesium = 0.8
- atoms with greater en. attract e. more
- Polar Covalent bonds form an unequal sharing of e.
- Non-Polar Covalent bonds form from equal sharing

Bonds:
- the type of bond formed can be produced by looking at the difference in en. of elements
     - if (en. > 1.7), it is an Ionic bond
     - if (en. < 1.7), it is a Polar Covalent bond
     - if (en. = 0), it is a Non-Polar Covalent bond


EXAMPLES:


1. Predict the type of bond formed.

                         F  -  F

Identify the electronegativity of each element: The electronegativity of Fluorine is 3.98.
Find the difference by forming and solving an equation: 3.98 - 3.98 = 0.00
State what type of bond was formed: Because the electronegavitity of this bond is 0.00, we may conclude that this is a Non-Polar Covalent bond.

2. Predict the type of bond formed.

                         Mg  -  S


Identify the electronegativity of each element: The electronegativity of Magnesium is 1.31, and the electronegativity of Sulphur is 2.58.
Find the difference by forming and solving an equation: 1.31 - 2.58 = -1.27 = 1.27 (NOTE: find and use the absolute value)
State what type of bond was formed: Because the electronegativity of this bond is 1.27, we may conclude that this is a Polar Covalent bond

3. Predict what time of bond was formed. Then identify the positive and negative sides of the following bond.

                         Ca  -  Se


Identify the electronegativity of each element: The electronegativity of Calcium is 1, and the electronegativity of Selenium is 2.55.
Find the difference by forming and solving an equation: 1 - 2.55 = -1.55 = 1.55
State what type of bond was formed: Because the electronegativity of this bond is 1.55, we may conclude that this is a Polar Covalent bond.
State which side is negative, and which side is positive: The electronegativity of Selenium is greater than the electronegativity of Calcium. From this, we may conclude that Selenium is the negative side and Calcium is the positive side because the electron will be attracted to Selenium.
Represent this with a diagram: δ + Ca  -  Se - δ

Acid-Base Reactions (brian)

strong acids & strong bases:
-strong acids(SA) dissociate to produce H+ ions
-stong bases(SB) dissociate to produce OH- ions
-when a SA and SB mix they form water and an ionic salt
-total volume changes
NaOH + HCl > NaCl + H2O

pH & pOH:
-pH is a measure of the hydrogen ions present in a solution
pH = -log[H+]
-pOH is a measure of hydroxide ions present in a solution
pOH = -log[OH-]

 

 

Ion Concentrations (brian)

Dissociation:
-ionic compounds are made up of 2 parts
 a) cation - positively charged particle
 b) anion - negatively charged particle
-when ionic compounds are dissolved in water the cation and anion separate from each other
-this process is called dissociation
-when writing dissociation equation the atoms and charges must balance
-the dissociation of sodium chloride is
NaCl > Na+ + Cl-
-if the volume does not change then the concentration of individual ions depends on the balanced coefficients in the dissociation equation

Example: BaSO4 > Ba2+ + SO4 2-
Example: 0.250M solution of KOH
               KOH >     K+      +  OH-
             0.250M  0.250M  0.250M