When atoms are bonding, they ofter bond with some angles. A simple theory that enables the chemist to correctly predict the geometries of most substances is the valence-shell-electron-pair-repulsion-theory. We can say that as VSEPR.

Basicly VSEPR will have three situtions.

1, Three atoms. Example BeCl2

Cl----Be----Cl      In this example, we calculate the angle between two non central atoms with the central atom.  Therefore the angle betwee Cl and Cl is 180. We call it LINEAR shape.

2, Four atoms. Example BF3

                     F     F
                      \    /
                        B
                        /
                       F                             The angle between F and F is 360/3=120
We call it Trigonal planar.

3, Five atoms. Explam CH4

                         H
                        /
                 H--C--H
                      /
                    H                                This one is special. When five atoms are bonding with a central atom. The angle will be 109.5

Organic Naming

Alright guys, this is gonna be Organic Naming - last blog of the year :)

Alkanes + Alkene + Alkyne

Contain the carbon chain with:

• Alkane has single bond (replace "e" with "ane")
• Alkene has double bond (replace "e" with "ene")
• Alkyne has triple bond (replace "e" with "yne")

How to name:

1. Count the longest carbon chain and come up with their name. ( methane, ethane ... )
2. Find out if there's any branch attached to the chain
3. Put the number indicates the branch's location in the carbon chain with the branch's name. Example: the methyl group locates in the 3 carbon of the chain --> 3-methyl
4. If there are more than 1 group then remember to put them in alphabetical order
5. If there are more than 1 same group at the same location, put their number of location including di, tri, tetra, penta ... Example: there are 2 methyl group at carbon 4 of the chain --> 4,4-dimethyl
6. Combine it with #1

Example:

Here we see that the longest chain has 4 carbons with single bond --> butane
there's a methyl group at carbon #2 --> 2 methyl
==> 2-methyl butane

Halides (Halogen) and Nitro

Halides and Nitro are group that has halogen element as a branch or NO2 (nitro) as a branch
How to name:

1. Follow exactly the rule above
2. Replace the ending of the element's name with "o"

• Br = bromo
• Cl= Chloro
• F= Fluoro
• I= Iodo
• NO2 = nitro

Alcohols

An alcohol is an organic compound that contains (-OH) functional group

 How to name: 

1. Use the longest chain that contains -OH. 
2. Replace the ending "e" by "ol". Example : Ethane --> Ethanol
3. Remember to make sure that you're in the lowest number and alphabetical order

Example:
We can see that the longest chain is ethane and -OH is in the first C --> no need to write number

--> the compound's name would be Ethanol or 1-Ethanol 

Properties:

• The -OH is an alcohol makes this compound soluble in water but then the hydrocarbon chain tends not to solute in water
• And boys, alcohol is poisonous lol! 

Aldehyde and Ketone

Both are contain carbonyl ( =0 )

Aldehyde

Aldehyde has the double bond O at the beginning of the chain.

How to name:

1. Find the longest chain of carbon, replace "e" by "al"
2. Make sure that you're in the lowest number and alphabetical order

Example:

We can count that the longest chain that contain =O has 8 carbon --> Octane

But because of the =O --> replace "e" by "al" --> Octanal

There's no more branch so our compound name would be Octanal

Ketone

Ketone is basically the same as Aldehyde but it contains the =O anywhere in the middle of the chain.

How to name:

1. Find the longest chain of carbon, replace "e" by "one"
2. Make sure that you're in the lowest number and alphabetical order 

Example:

We count the longest chain that contains =O has 4 carbon --> butane

But the =O locates in the 2nd carbon of the chain --> it's an Ketone --> change Butane --> Butanone

Properties of Ketone and Aldehyde

• Both are soluable
• Aldehydes are very reactive, easily converted to Carboxylic Acids
• Ketones are relatively unreactive

Carboxylic acids

Carboxylics are formed by and (=O) and (-OH) group

How to name:

1. Follow the basic naming
2. Replace the "e" in the longest chain by "oic" and "acid" at the end
3. Make sure that you're in the lowest number and alphabetical order 

Example:

1.  The longest chain has 4 carbons --> butane
2. There's the (=O) and (-OH) branch attached --> it's an Carboxylic acid
3. There's also the Chloro branch in the 3rd carbon and methyl brach in the 2nd carbon
4. The compound's name would be 3 chloro 2 methyl butanoic acid

Properties:

• Carboxylic acids can be neutralized with a base

Ester

Easters are basically the combination of Carboxylic Acids + Alcohol

 

How to name:

1. Follow the basic naming rules
2. Name the R' carbon chain first as normally ( methyl, ethyl ... )
3. Then name the R carbon chain and replace an "e" ending with "oate"

Example:

We can see that the R' carbon chain has 3 carbons --> propyl

The R carbon chain has 1 carbon --> methane but it's an esters --> replace an "e" with "oate"

==> Propyl methanoate

Properties:

• Ester have pleasant, fruity odors ...

Ethers

In ethers, Oxygen connects to 2 alkyl chain

 How to name:

1. We follow the basic rule for naming
2. Name the short chain first then the longer chain second
3. The longer chain would be at last of naming ( basically alkyl )
4. The shorter chain would be named at first, replace "e" by "oxy"
5. basic ethers is methoxy methane

Example:

Properties:

• Highly flamable
• Insoluable in water
• Good solvent for organic compound

Amines

Nitrogen bonds to H

How to name:

1. Follow basic naming rules
2. Add (-amino) with it's location in the carbon chain
3. Ending with the longest carbon chain ( methane, ethane ..)

Example:

The longest carbon chain has 5 carbon --> pentane

The amino branch locates in the second carbon of the chain -> 2 amino

==> 2 amino pentane

Properties:

• Soluable
• Fishy odors
• Amines are organic base that easily form salts when react with acid

Alicylics 

Use the same rule as Alkane and Alkene, just need to add "-cyclo" in front of the longest chain's name

The structure is gonna be ring, so depends on how many C in the longest chain, we would draw the appropriate ring

Example:

The ring has 6 carbons --> hexane

there are 3 methyl branches at location 1,2,3 

=> 1,2,3 trimethyl cyclohexane

Note: If there's a double bond or triple bond, have to start counting from the beginning of the double bond or triple bond so we can get the lowest number.

Aromatics

Is the ring that contain benzene.

Follow same rule as alicylics

If benzene appears as a branch, add "phenyl" otherwise just add benzene at the end of your compound's name

Ex: 1,2,3,4 tetraphenylpentane

Ex: 1,2 dimethyl benzene

NOTE: All of the naming must be in the lowest number and alphabetical order

Lewis and Electron Dot Diagrams

Okay, most of you know the Bohr Model... right? Well Lewis models are sort of like Bohr Models but with only the valence electrons around them.
Valence electrons are.... Electrons in the outermost shell of an element or atom. Also called the "reactable electrons."
Sometimes Lewis diagrams are called dot structures because the diagram is made of dots, obviously.
So how do you draw a Lewis/ Dot Diagram?
Step One - What element are you drawing?? Count the electrons.
Step Two - Place the valence electrons around the element symbol.




For more information about Lewis Daigrams, check these websites out!
http://chemistry.about.com/od/generalchemistry/a/lewisstructures.htm
http://www.ausetute.com.au/lewisstr.html

Chemical Bonds and Electronegativity

There are 2 kinds of bonds...

Covalent bonds (Non- Polar Covalent bonding) - when electrons are shared EQUALLY. Bonding between non-metals (negatively charged).

Ionic bonds (Polar Covalent Bonding) - when 1 atom has a greater attraction for the electrons than the other atom. Bonding between non metals and metals

Electronegativity - the attraction of an atom towards its shared pair of electrons in a chemical bond.

^ Use me to help you understand more about electronegativity!!

To learn more about chemical bonds, check out these websites!

http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond.html

http://www.visionlearning.com/library/module_viewer.php?mid=55

Electronegativity and Polarity

 Hello, and today in class we have discussed Electronegativity.  Now what is this large word?

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

After reading this definition, you may be wondering, what does that mean???  Well, here is a chart to help you understand better of what it means.

According to this chart, electronegativity values are much more higher at the family of noble gases, and on the far left of the table, the electronegativity is the weakest.

The formula for determining how high the value is, is to use the equation: |value| = |energy1 - energy2|.  Notice the absolute value bars.  Those indicate that the value will always be positive.


Here are some rules to follow:

1. Non-Polar Covalent bonds are formed when the difference between the values is less than 0.5
2. Covalent bonds are formed when the difference is between 0.5 and 1.8
3. Ionic bonds are formed when the difference is over 1.8


Lets do an example:  Hydrogen and Fluorine.


Hydrogen's value is 2.2 and Fluorine's value is 3.98.


3.98-2.2 = 1.78.


These two are covalent bonds because when formed, the difference is between 0.5 and 1.8!

Here is a video, if you guys still do not understand.  Enjoy!

Periodic Table Trends

HELLO!  HOW YOU DOING!  Okay, so today we went to the lab and discovered different types of trends using Microsoft Excel.

BACKGROUND
In 1870, Dmitri Mendeleev first proposed a new of studying and organizing the then known 63 elements. The modern form of the table has been modified and improved many times since Mendeleev's tables.  Pioneers like Moseley(1913) and Seaborg(1941) have made the properties of the elements much simpler to study and understand.

So, the important trends to remember:

Electronic Structure - Electron configuration and Valance Electron.

Brief summary through definition and some new vocabulary:

•  Energy level: the amount of energy that electron can possess.

• Ground State: it is when all the electrons are in lowest energy level.
• Excited State: when electrons are in the energy level that different from the lowest level
• Orbital: is the region, like the milky way surrounding around the nucleus that electron occupies in particular energy level
• A shell: is the set of all the orbitals have same energy levels

• Sub-shell: is the set of orbital of the same types (s,p,d,f) 

• Electron Configuration: is the notation that describes the orbital in which electron occupies and the total number of electron each orbital

 

 Or this

Actually, i find the first chart easier to count and do exercise but its up to you. Here's how ->
Usually in test you will be given question like this: Given element Na, write the electron configuration. Don't freak out yet, follow these steps !

1. Look into your periodic table to find that element. In this case, we found Na located in Group IA, period 3
2. Then find the element's proton's number, usually in the top left in the box
3. We all known that if the element is not ion, the number of electron = number of proton
4. So we will be able to know how many electron are there in the element. Okay keep in mind that number.
5. then we follow the route on the periodic table from left to write, top to bottom
6. So finally we just follow that route till we reach that element
7. I can write without think of anything: 1s2 2s2 2p6 3s1

Oh snap i forgot to mention the core notation. Arr i hate chemistry name so much, the core notation is basically the short form of the electron configuration that is easier and faster to write. Its in the form of [X] s(x) p(y) ... Here are steps:

1. Follow steps 1 above
2. Look backward to the previous row, then find the noble gas ON THE BACK ON YOUR ELEMENT, NOT IN FRONT OF
3. Write that noble gas in bracket in this case [Ne]
4. Then continue to write the electron configuration till you reach your element. => [Ne] 3s1

 Here are some scientist contributed to this concept

1. The Pauli Exclusion Principle: in every given energy level, each orbit can only contains 2 electrons

1. The Niel Bohr Principle: electron exists in a specific energy states and can be filled up from low level to high level

1. Hund Rule: the Hund rule states that electron don't pair up unless they have to, that means they will fill out 1/2 the orbit first.

Valance Electron:

It's basically the number of electron in the outer most shell. Or orbital

Ex: The Valance Electron of Na ( [Ne] 3s1 ) is 1 cause there's only 1 electron in the outer most shell

A little history about the atom

DEMOCRITUS

• Stated that atoms were different in form, position and magnitude; all things were made of atoms, and atoms were small, full, unbreakable, pore-less and homogeneous.

ANTOINE LAVOISIER

• Proved the law of conservation of mass around 1789.

JOHN DALTON

• Formed the atomic theory: all matter is composed of tiny, indestructible particles.

JJ THOMSON

• discovered the election

ERNEST RUTHERFORD

• Atomic model made.
• Using gold foil experiment, discovered alpha and beta rays and presumed electrons were located outside nucleus.

ROBERT MILLIKAN

• Using falling-drop method, proved that the charge was a constant for all electrons therefore demonstrating atomic structure of electricity.

MARIE CURIE

• Studied radioactivity; concluded that the ability to radiate didn't depend on arrangement of the atoms in a molecule but that it has to be linked to the interior of the atom itself.

JAMES CHADWICK

• Proved the existence of neutrons: particles without electrical charge.
• The neutron has a similar mass to a proton.

MAX PLANCK

• Originator of quantum theory.
• Discovered that light was released in heat sources in a pattern of frequencies for different elements.

ALBERT EINSTEIN

• Established the law of mass, theory of relativity and using Planck's theory, formulated photon theory of light.

LOUIS DE BROGILE

• Believed electrons acted like particles and waves
• Waves produced by electrons contained in orbit had certain energy, frequency and wavelength

JOSEPH LOUIS PROUST

• Established law of definite composition and law of definite portions

ERWIN SCHRODINGER

• Combined equations for behaviour of waves with Brogile's equation of electrons in atom.

NIEHL'S BOHR

• Propsed Bohr model (modified Rutherford model)
• Proposed that electrons travel in certain successively larger orbits.
• Electrons jump from outer to inner orbit which emits light

To learn more about these AMAZING scientist... feel free to check out these sites!

http://hi.fi.tripod.com/timeline/

http://atomictimeline.net/index.php

Structure of the Atom

Structure of the Atom


Hello all, today we learnt about the structure of the atom woooohoooo.  Here is what we learned!

An atom contains 3 subatomic particles called:

protons
-Represented as 1
                          1 P

electrons
-Represented as 1
                          0 N

neutrons
-Represented as 0
                         -1 E

On the periodic table:

Atomic Number = # of protons = # of electrons
Atomic Mass(average) = # of protons + neutrons

Ions = # of electrons - charge

Anions = negatively charged ion

Cations = positively charged ion

What are isotopes?  Well they are:

-The same element, but heavier.

                         

Lab 6D- Determining the Limiting Reactant and Percent Yield in a Precipitation Reaction

Alrighty! So, why are we doing this lab?

We, as diligent chemistry students, want to find out the reaction between the solutions NaCO3 and CaCl2, determine which is limiting and which is excess reactant, determine what the theoretical mass of the precipitate that should form, AND to compare the actual mass to the theoretical mass of the precipitate and calculate the percent yield.

In order to do this lab you will need...

• SAFETY GOGGLES. (Here's the thing, it might shock you... deep breath... YOU MIGHT NEED YOUR EYES IN THE FUTURE. LE GASP!)
• 1 Centigram
• 2 gradulated cylinders (25mL)
• 1 beaker (250mL)
• 1 wash bottle
• 1 filtering apparatus (1 ring stand, Erlenmeyer flask (250mL), 1 funnel)
• 1 filter paper
• 25mL of 0.70M NaCO3 solution
• 25mL of 0.50M CaCl2 solution

Now, after you've got all your things, all you have to do is...

1. COMBINE the NaCO3 solution with the CaCl2 solution
2. Observe... wait now for 5 minutes. You can weigh your filter paper.
3. While waiting for the reaction to fully react, set up your filtering apparatus.
4. When setting up your filtering apparatus, using the wash bottle, lightly wet the filter paper so it sticks to the funnel.
5. Swirl your beaker of precipitation and slowly pour your solution into the apparatus. Take your time with this.
6. Using the wash bottle, squirt some water into the beaker to get the remaining precipitate out. Also rinse the precipitate in the filter paper to remove the NaCl2.
7. Remove the filter paper and let it dry.
8. Clean up.

Day 2

1. After it has dried, weigh it again. Record.

Now, wasn't that easy? And also SOOOO fun? Do you know what this white precipitate is? It is actually.... *drum roll*

CHALK?! (Don't worry it won't kill you... BUT THAT DOESN'T MEAN YOU SHOULD EAT IT.)

The equation for this bad boy...

1 Na2CO3 + 1 CaCl2 --> 2 NaCl + 1 CaCo3

Have Fun!!

Percent Yield and Percent Purity

Percent Yield
In chemical reaction, products are always not the same as in calculation. For example, in stoichiometry calculation, we are supposed to get 12g CaCO3 in this reaction: Ca(OH)2 + H2SO3 ------CaSO3 + 2H2O. But in fact we just get 8g. The reason might be impure reactants. Therefore, we have Percent Yield.


Percent Yield is the percentage of real mass we get by the calculation results.

% Yield = actual mass / calculation mass

Percent Purity
Same as the other substance. Sometimes the substance might not be absolute pure. For example, gold alwas contains impurities in it.

% Purity = pure mass / whole mass

Excess and Limiting quantity

so we've learned a new way that most of the reactions accur don't use up all of the reactant but will be some left over.
For example when i have 40 speakers and 10 mics. Provided that to make a head set, you need 2 speakers and 1 mic. So for the amount I have before, i can only make 10 headsets right? And of course there will be 20 speakers left.
So does in the reaction, usually it's not used all of the amount of reactant to form product. That's why today we learn how to calculating that left over.

During my review for the HORRIBLE TEST, i just realized a very helpful strategy to solve this problem without any concern. HERE YOU GOOOO:

So i'm gonna get a problem in the review sheet.
If 15 grams of Cu (II) Chloride react with 20 grams of NaNO3
a/ Write balanced equation (c'mon EASIIIIIIIIIIIII)
b/ What is the limiting reagent
c/ How much NaCl can be formed ?

I BELIEVE THAT WHEN YOU SOLVE THIS PROBLEM PRECISELY, YOU’RE GONNA BE ABLE TO SOLVE ALL THE OTHER PROBLEMS.

CuCl2 + 2 NaNO3 à Cu(NO3)2 + 2 NaCl

Mole in equation: 1 2 1 2

Mole actually reacted 0,1 0,2 0,1 0,2

So basically you calculate the mole from the question. Because they’ve given you the mass of both reactants so you can calculate it.

Mole CuCl2 : 15/135 = 0,1 moles

Mole NaNO3: 20/85 = 0,24 moles

After this, you would have to compare between 2 moles above by getting the ratio between that and the mole in equation.

So: 0,1/1 < 0,24/2 => the theorical mole of NaNO3 is larger than CuCl2 à we can easily say that CuCl2 is the limiting quantity.

From this, please forget about the mole of excess (NaNO3) cause we can only use the limiting moles to calculate thing. Plug it into your equation and calculate the other moles by their coefficient.

c/ in order to calculate the excess mole, you just get the mole just calculated from the given information (0,24) subtract by the mole that actually reacted (0,2) then you can get 0,04 mole of left over.

The secrets of STOICHIOMETRY

Hello there.  You may be wondering, what Stoichiometry means.  Well:

Stoichiometry is the quantitative analysis of chemical reactions and is about measuring the amounts of substances involved in a reaction.


What??  You don't know what this means??  Well, to put it into more simple english, it is the study between the amount of reactants used in a reaction and the amounts of a products produced by a reaction.

In more simpler english, it is the study of ratios between reactants and products.


Here is a sample question of stoichiometry:

For the equation: Zn + 2HCl ---> ZnCl2 + H2

1) How many atoms of Zn are needed to produce 1 molecule of Hydrogen?
Answer: 1, because the ratio of Zn to Hydrogen is 1:1, therefore the answer is 1.


2) How many grams of Zinc Chloride will be formed when 2.00g of Hydrogen is formed?

Step 1 - Convert 2.00g of Hydrogen to moles

2.00g x 1 mol/2.0g = 1 mole of Hydrogen.

Step 2 - Plot the mole into the mole ratio.

In this case, the ratio is 1 mol ZnCl2 : 1 mol H2, because there is one mole of hydrogen.

Step 3 - Answer the question, in this case, convert the moles back into mass.

1 mol ZnCl2 x 136.4g/1mol = 136.4 g of ZnCl2

136.4g of ZnCl2 will be produced when 2.00 g of H is formed.


Still don't understand?  Watch the video to learn more!

Balancing Equation

Here is an equation

K+O2 ---K2O
It's a skeleton equation. It showed what the reactants and products are. But not ALL the atoms. On the left, it has one K, two O. But on the right, It has two K and only one O. Therefore we need to balance it.

A balanced chemical equation shows all atoms.

Because on the left it has two O. so we need to add up the number of O on the right hand side. Write down 2 before K2O. And we have 4 K and 2 O. balance the K. Write down 4 before K on the left hand side.

Here we have a balanced equation.     4K+O2 ---- 2K2O

Some tips for balancing equation

1. draw a chart and write all the numbers of atoms, that makes faster and easier calculation
2. assume the most complicate compounds as 1
3. always double check after balancing

Translating Word Equation/naming compounds

Translating Word Equation.

There are two ways to write an equation, word equation and symbolic equation.
Word equation contains reactants and products, no need for balancing.

Example:
This is a symbolic equation 2NO+O2-----2NO2
change it into word equation:
Nitrogen monooxide+oxygen-------nitrogen dioxide.

1. name the compound names first.
2. write down the equation.

Naming compounds

two types of compounds: ionic and covalent
   
 Ionic compound

1.  no prefix needed. But have to drop the end of negative ion and add -ide
2. Roman numerals are used following the positive ion to indicate which ion was used.

Example: manganese(III) sulfide                 ---- Mn2S3


Covalent compounds

1. Prefix is needed. (1-mono 2-di 3-tri 4-tetra 5-penta 6-hexa 7-hepta 8-octa 9-nona 10-deca)
2. drop the end of negative ion and add -ide

Example: N2O4         ----------dinitrogen tetraoxide

Pre-Lab 5B Types of Chemical Reactions

Pre-Lab Types of Chemical Reactions


Objectives
1)  To observe a variety of chemical reactions.
2)  To interpret and explain observations with balanced chemical equations.
3)  To classify each reaction as one of the four main types.

Supplies

Equipment

lab burner
6 test tubes
      one will be flame heated
test-tube clamp
medicine dropper
wood splints
cruicible tongs
steel wool
safety goggles
lab apron

Chemical Reagents
copper wire(bare)
iron nail
0.5M copper(II) sulfate solution
solid copper (II) sulfate pentahydrate
water
0.5M calcium chloride solution
0.5M sodium carbonate solution
mossy zinc
2M hydrochloric acid solution
hydrogen peroxide solution(6%)
manganese (IV) oxide


Procedure

1)Put on lab coat and goggles
2)Observe before, during , and after each reaction.  Record in table one.
Reaction one
3) Adjust burner flame to high heat

4)Using crucible tongs, hold 6 cm length bare copper over hottest part of flame for a few minutes.
Reaction Two
5) Clean iron nail with steel wool until it turns shiny
6) Nail in tube and copper(II) sulfate solution so half of nail is covered.
7) After 15 minutes, remove nail and note changes








Reaction Three
8) Put solid copper(II) sulfate penta hydrate until the tube is one third full.
9) With clamp, angle away from peers and heat (back and forth gently)
10) Continue until no more changes.

             





Reaction Four
11) Allow contents from reaction three to cool.
12) Use medicine dropper to add two or three drops water to tube.

Reaction Five
13) Fill a tube a quarter full with calcium chloride solution.  Fill second tube 1/4 full sodium carbonate solution.
14) Pour calcium chloride into the sodium carbonate solution.





Reaction Six
15)Place a piece of mossy zinc into the test tube.
16) Add HCl into the tube until the zinc is completely covered

Reaction Seven
17) Half fill a tube with hydroperoxide.
18) Add small amount of manganese (III) oxide.
19) Test gas by placing glow(NOT BURNING) splint into the mouth of a tube.

20) Clean-up!