May 30, 2011

Hello everyone! Hope all of you are doing good. Gosh can you believe that school is almost over!!! OMG!! lol :) So let's get going right away, in class yesterday we learned about Alkenes & Alkynes.

Alkenes and Alkynes
- Carbon can form double and triple bonds with Carbon atoms.
- When multiple bonds form, fewer hydrogens are attached to the Carbon atom.
- The position of the double/triple bonds always has the lowest number and is put in front of the parent chain.

Alkenes
- Alkenes are hydrocarbons with one or more double bonds located between carbon atoms leading to an "unsaturated" hydrocarbon.
- The ending is changed from -ane (alkane) to -ene for alkenes
- ex. CH2 = CH2 equals to ethene
- With Alkenes, some molecules have the same structure but different geometry. This is called Geometric Isomers.
- If two adjacent carbons are bonded by a double bond AND have side chains on them two possible compounds are possible = Cis or Trans.
- Cis: If the larger groups are both above or below the plane of the bond.
- Trans: If the larger groups are across the plane of the bond.
- If there are two identical groups on either end of the double bond, there is no need for cis or trans.

Alkynes
- Alkynes are hydrocarbons with one or more triple bonds located between carbon atoms leading to an "unsaturated" hydrocarbon.
- The ending is changed from -ane (alkane) to -yne for alkenes
- ex. CH =(add a dash to the equal sign for the triple bond aka three lines) CH equals to ethyne

Now here are some images:
















Videos:
1) http://www.youtube.com/watch?v=l6m7zOto9oU
2) http://www.youtube.com/watch?v=KWv5PaoHwPA&feature=related
3) http://www.youtube.com/watch?v=6NygjuEFkIc
4) http://www.youtube.com/watch?v=3cfVBC2pS38&feature=relmfu
5) http://www.youtube.com/watch?v=jF46f8vkJPg&feature=related
6) http://www.youtube.com/watch?v=ryTCHJIi6d8&feature=related

Worksheets:
1) http://www.gahrhs.org/ourpages/auto/2010/5/28/39679088/Alkene%20Alkyne%20worksheet.pdf
2) http://www.pkwy.k12.mo.us/west/teachers/anderson/pack10/WS107.pdf
3) http://fcw.needham.k12.ma.us/~Janet_Fasano/FOV1-00108B66/FOV1-0010CD86/Alkene%20and%20Alkyne%20Worksheet.pdf
4) http://ewalerko.net/grs0025t.pdf

Well that is it.... for now!! Have a great day everyone! :)

Organic Chemistry

ORGANIC CHEMISTRY seems like another major headache as you have probably heard or assumed, but it is NOT! I ganrantee that it is as simple as any other chemistry topics we have covered except with a little more elaboration on top of the basics! ^-^

Now, Organic chemistry is simply the chemistry of carbon?...not quite....because such compounds like CO2, CO, CN are NOT organic! So Why do they say Organic Chemistry is the chemistry of carbon?
Well, it is actually the chemistry of hydrocarbons= carbons and hydrogens. And the end products are amazing! They examplify our everyday products such as clothing, plastic, alcohol and much more...

But those two are just the basic requirement of organic compounds, we can also add Oxygen, Nitrogen, etc. to elaborate...oops..seems like I have spilled the next topics...>. >''

Special properties exclusively to Organic Compounds are:
1. low melting points
2. weak/ non-electrolytes
3. from chains of carbon atoms linked in:
 a. straight line

 b. circular pattern

 c. branched pattern

4. can be linked in single bond, double bond, and triple bond.
single bonds are called alkane, double bonds are called alkene, triple bonds are called alkyne.

Properties of Alkanes:

1. Saturated hydrocarbons with single bonds!
2. compounds usually end with -ane
3. represented with structural, condensed, molecular and ball-stick model (rarely used)
* Abbreviated formula = condensed formula


Here is a table of three different formulas.
Have you noticed a pattern between the Carbon molecules and Hydrogen molecules?
...If you didn't I will show you now  "C n H 2n+2"

Alkanes can be branched or subsitutited with Alkyl groups which is an alkane having lost one Hydrogen atom. The alkyl groups end in "-yl":



This is an example of a branched hydrocarbon named 2-methylbutane


Naming is the toughest part, but also the neatest of Organic Chemistry, so pay attention!

Rules for Alkane Nomenclature (IUPAC):

1. consider LONGEST CONTINUOUS CHAIN

2. Name the alkyl groups attached

3. give carbon number where the alkyl group has the lowest carbon number

4. put Carbon#(if repeated, then put twice and separate with a "comma")-alkyl name (if repeated use prefixes to indicate: Dimethyl, tetraethyl,...)the longest chain name.

Longest chain =the circled chain = 6 = heptane
CH3 = methyl = branched from Carbon # 3
Therefore... 3-methylpentane

PRACTICE!
Let's Repeat the process and keep this rule in minds...
abbreviated line formulas (A through E):

Answers: A. heptane B  2-methylpentane    C  3-methylpentane    D  2,2-dimethylbutane    E  2,3-dimethylbutane

Reading might not be the learning tool for you, but internet might be... This video is prepared for visual or audio learners! It was a very inspiring tutorial video for me, I have confidence that this will also amuse you at the same time educate you about ORGANIC CHEMISTRY, thank you for coming and CYA!~~

http://www.5min.com/Video/Learn-about-Organic-Chemistry-3-111429856
 ORGANIC CHEMISTRY 3
There is a series of tutorial ongoing for Organic Chemistry, so you will get the full picture!
http://www.5min.com/Video/Learn-about-Organic-Chemistry-4-111430078
ORGANIC CHEMISTRY 4

May 18, 2011

Hello, Hello Everyone! How are y'all doing? Can you believe all this sun today!!!! It is sooo nice and sooo beautiful! And the sun is not just stopping here in Vancouver, apparently it is 17 degrees celsius in the interior of BC, 40 degrees celsius in Manitoba, and 23 degrees celsius in Edmonton. Not to mention that this weather is perfect timing for the long weekend!
Ok, let's move on to what we did in class yesterday. Look down below for what we learned..... plus see some additional cool stuff under the info!

˜Chemical Bonding

- Chemical bonds happen when electrons from one atom are attracted by the nucleus of another atom.  
- There are three types of chemical bonds:
Nonpolar Covalent Bond = electrons are shared equally.
Polar Covalent Bond = electrons are shared unequally.
Ionic Bond = electrons are transferred between two atoms.


˜Electrostatic Force

- Opposite charges attract each other.

- Like charges repel each other.

- The greater the distance = the smaller the attractive force.

- The greater the charge = the greater the force of attraction.

- Electrostatic force is a force that exists between charged particles as a result of attraction or repulsion. This force goes in all directions.

˜Ionic Bonds

- Metals tend to lose their electrons, then nonmetals gain these electrons. Note that these electrons are transferred, not shared.

- When nonmetals lose electrons  = positively charged ions (cations).

- When metals gain electrons = negatively charged ions (anions).

- Cations attract anions, and vice versa. This refers to an electrostatic attraction.

- Ionic bonds are very strong and an enormous amount of energy would be needed to break them apart. These ionic compounds also have high melting tempatures.

- Electronegativity = the measure of the tendency of an atom to attract electrons from a neighbouring atom.

- In general,

Metals = low electronegativity values.

Nonmetals = high electronegativity values.

- The scale that is used to measure electronegativity is called the Pauling Scale. The scale goes from 0.7 to 4.0.

- High electronegativity values equals to high ionization energy.

- To calculate an electronegativity difference:

ENeg Diff. = |ENeg1 - ENeg2|

1) If ENeg Diff. <0.5

It is a non-polar covalent bond.

2) If ENeg Diff. = 0.5 and = 1.8

It is a polar covalent bond.

3) If ENeg Diff. >1.8

It is an ionic bond.

˜Nonpolar Covalent Bonds

- When two atoms have less than full shells are able to share to attain a full electron shell.

- Nonpolar covalent bonds are very strong and an enormous amount of energy would be needed to break them apart. 

- Some compunds have negative melting points which would be: CH4, O2, F2.

- Intramolecular Forces = found within a molecule, responsible for holding the atoms of a molecule together.

- Intermolecular Forces = between the molecules, responsible for the bonding between molecules.

˜Polarity

- Describes a molecule's electrical balance.

- If there is an imbalance with electrical charge, than a molecule is polar.

- If the electrical charge is the same strentgh, then it is nonpolar.

˜Polar Covalent Bonds

- Electronegativity difference. (refer to above)

- the atom with higher electronegativity = partial (negative) charge.

- the atom with lower electronegativity = partial (positive) charge.

˜Images, Videos, Worksheets

Images

Ionic Bonding

Polar Covalent Bonding

Polar Covalent Bonding

Polar Covalent Bonding

Polar Covalent Bonding

Polar Covalent Bonding

Ionic Bonding

Ionic Bonding

NOTE: Shows Valance Electrons!

Sodium Chloride Crystal Structure

Videos

1) http://www.youtube.com/watch?v=QqjcCvzWwww

2) http://www.youtube.com/watch?v=C6o-eqGUBCY&feature=related

3) http://www.youtube.com/watch?v=WaPxTAeW5e8&feature=related

4) http://www.youtube.com/watch?v=CGA8sRwqIFg&feature=related

5) http://www.youtube.com/watch?v=mtRgeBSe1o8

6) http://www.youtube.com/watch?v=HCBsE6CDjKc&feature=related

7) http://www.youtube.com/watch?v=Kj3o0XvhVqQ&feature=related

Worksheets

1) http://misterguch.brinkster.net/ioniccovalentworksheets.html

2) http://butane.chem.uiuc.edu/cyerkes/Chem102AEFa07/worksheets/Worksheet%2013.pdf

3) http://www.avon-chemistry.com/bonding_wrkst.html

4) http://schools.bibb.k12.ga.us/16542091810856967/lib/16542091810856967/ChemicalBondingWorksheet.pdf

5) http://www.creative-chemistry.org.uk/gcse/documents/Module8/N-m08-15.pdf

6) http://misterguch.brinkster.net/PRA012.pdf

Ok, well I am done for today. Everyone enjoy your long weekend!!!! :)

May 10th

Today we're going to teach you how to draw some diagrams! :)


Oh no, are those the same BOHR-ing Bohr diagrams again?!





Nope! These are all-new, EXCITING Chem 11 diagrams that you've never heard of before! To start off, we have the electron dot diagram!

Electron Dot Diagrams

For these diagrams, there are a couple of things you need to know:

• the nucleus, aka the centre of the diagram, is the atomic symbol of the element you are drawing
• bonds can be drawn on all four sides of the "nucleus" or atomic symbol
• each single dot represents one bond
• each side must have at least one bond/"dot" before you can add on a second one
• valence electrons are shown

Here, N2 is shown as an example:





Lucky Number Eight:


One thing you have to remember when drawing electron dot diagrams is the Octet Eight rule: every single element MUST have eight dots surrounding its nucleus. WHY? Because in order to have a stable valence shell like the noble gases, it must fill its outermost shell with eight electrons!


The ONE exception is Hydrogen, which is happy with just two "dots".





Notice how the Carbon has eight electrons, while each Hydrogen has two. Everyone is happy, because they are sharing, yay.

Lewis Structure Diagrams

In Lewis structure diagrams, Hydrogen and Fluorine never go into the centre. The metal goes into the centre, or the element which requires the most valence electrons to gain stability.


Adding and Subtracting:


For Lewis diagrams, add up the total number of valence shell electrons, THEN add or subtract the charges on the compound to find out how many "dots" there should be in your diagram.


For example, for NO3, the charge is -1. N has 5 valence electrons, O has 6. 5 + 6 + 1 (for the added electron that caused the negative 1 charge) is 12. There should be 12 dots in the diagram.


In ionic compounds, draw a big [ ] around the entire structure, and add the charge on the top right-hand corner, like so:





In covalent compounds, use lines to indicate bonds.

CLICK HERE TO TEST YOUR KNOWLEDGE ON LEWIS STRUCTURES!!!

Periodic Table Trends

The trends need to know are as follows:
1. Metallic properties
2. Atomic Radius
3. Ionization energy
4. Electronegativity
5. Reactivity
6. Ion Charge
7. Melting/Boiling Point
8. Density

If you were to look carefully at many of the properties of the elements, you would notice something besides the similarity of the properties within the groups. You would notice that many of these properties change in a fairly regular fashion that is dependent on the position of the element in the periodic table.  As you compare elements from left to right across the periodic table, you will notice a trend or regular change in a number of properties. The same thing happens if you go up and down on the periodic table and compare the properties of the elements. 

Atomic Radii

1) As you move down a group, atomic radius increases.

WHY? - The number of energy levels increases as you move down a group as the number of electrons increases.  Each subsequent energy level is further from the nucleus than the last.  Therefore, the atomic radius increases as the group and energy levels increase.

2) As you move across a period, atomic radius decreases.

WHY? - As you go across a period, electrons are added to the same energy level.  At the same time, protons are being added to the nucleus.  The concentration of more protons in the nucleus creates a "higher effective nuclear charge."  In other words, there is a stronger force of attraction pulling the electrons closer to the nucleus resulting in a smaller atomic radius.
 First Ionization Energy

Definition:  The energy required to remove the outermost (highest energy) electron from a neutral atom in its ground state.

1) As you move down a group, first ionization energy decreases.

WHY?
Electrons are further from the nucleus and thus easier to remove the outermost one. "SHIELDING" - Inner electrons at lower energy levels essentially block the protons' force of attraction toward the nucleus.  It therefore becomes easier to remove the outer electron

2) As you move across a period, first ionization energy increases.

WHY? - As you move across a period, the atomic radius decreases, that is, the atom is smaller.  The outer electrons are closer to the nucleus and more strongly attracted to the center.  Therefore, it becomes more difficult to remove the outermost electron.

Exceptions to First Ionization Energy Trends

1) Xs2 > Xp1  e.g. 4Be > 5B WHY? - The energy of an electron in an Xp orbital is greater than the energy of an electron in its respective Xs orbital.  Therefore, it requires less energy to remove the first electron in a p orbital than it is to remove one from a filled s orbital.  2) Xp3 > Xp4  e.g.  7N > 8O WHY? - After the separate degenerate orbitals have been filled with single electrons, the fourth electron must be paired.  The electron-electron repulsion makes it easier to remove the outermost, paired electron. (See Hund's Rule)

Metals

Common characteristics:

Metallic luster (shine)

Generally solids at room temperature

Malleable

Ductile

Conduct heat and electricity

Exist as extended planes of atoms

Combine with other metals to form alloys which have metallic characteristics

Form positive ions, e.g.  Na⁺, Mg²⁺, and Al³⁺

Nonmetals

Common characteristics:

Rarely have metallic luster (shine)

Generally gases at room temperature

Neither malleable nor ductile

Poor conductors of heat and electricity

Usually exist as molecules in thier elemental form

Combine with other nonmetals to form covalent

Generally form negative ions, e.g.  Cl^-, SO₄^2-, and N^3-

The differences in the characteristics of metals and nonmetals can be explained by the following:

Metals have relatively few electrons in their valence shells.

Metals have lower ionization energies than nonmetals.

Metals have smaller electron affinities than nonmetals.

Metals have larger atoms than nonmetals.

1) As you move across a period, metallic character decreases and nonmetallic character increases.

2) As you move down a group, metallic character increases and nonmetallic character decreases.

Semimetals (Metalloids)

A class of 8 elements that have properties of both metals and nonmetals.

B

Si

Ge

As

Sb

Te

Po

At

Reactivity
Metals and non-metals show different
trends.
The most reactive metal is Francium; the
most reactive non-metal is Fluorine

Ion Charge
elements ion charges depend on their
group (column).


Melting Point
Elements in the center of the table of the
highest melting point
Noble gases have the lowest melting
points
Starting from the left and moving right,
melting point increases (until the middle of
the table)

DENSITY
metals will tend to have higher density because of their positive charge. And radioactive elements also are also very dense. But you can say that as you go down the table, atoms are more dense.



Trend of Ionization:http://www.youtube.com/watch?v=ywqg9PorTAw
General Trend:http://www.youtube.com/watch?v=CHHy2ex0dw4
http://www.youtube.com/watch?v=h7XWqwgZII0&feature=related