Rings and Cyclones

All carbon bonds have the same reactivity because of something called delocaligation. However, all of the aromatic structures that we have learned about are not as reactive as cycloalkanes, which I will be explaining...

Benzene Rings

 This is an image of a Benzene Ring:

The circle in the center represents the electrons in the benzene ring which are "delocalized". This means that they can change position in the ring and are shared equally.





There are a few rules to follow when naming them:
- Side chains are give the name "phenyl"
- This can be a parent chain or a side chain
- Add "benzene" to end of name

For example:

The structure to the right's name would be:

1,2,4,5-tetramethylbenzene

This is because there are four methyl chains coming off of the 1, 2, 3 and 4 corners. As always, you chose the lowest numbers possible.



Here is a video to help you with Benzene Rings:

Alicyclics and Aromatics

- Many hydrocarbons form ring-shaped structures which are known as cyclic hydrocarbons (Alicyclics) and are named using the prefix "cyclo"

- Their general formula is CnH2n ("n" representing the number of Carbon atoms)

-Alicyclics are more reactive and less stable than straight chains

-Numbering for these can start anywhere, as long as they are the lowest numbers possible

Rules for Naming Cycloalkanes:

1. Count length of chain in ring

2. If only one side group, no number needed because it is assumed to be one

3. Cycloalkanes named like straight chain side group, except "cyclo" added to beginning of name

*Give the lower number to the side group that comes first alphabetically*

Cycloalkenes and Cycloalkynes

- More reactive than cycloalkanes

- Similar to cycloalkanes, except ending changed

- *When numbering these, the double or triple bond is always between carbon one and two*

For example:

First of all, you would find the longest chain of carbons. This would obviously be the hexene. It is in a ring, though, so it would be cyclohexene. If you then number all of the carbons, the smallest sequence for the methanes would be 1, 2, 4 and 5. The propyl group's number would be 3. If you put this all together you get:

1,2,4,5-tetramethyl-3-propylcyclohexene

AND THAT'S IT! LAST BLOG OF THE YEAR! YOU ARE NOW AN EXPERT CHEMIST! Well, in grade 11 chemistry, but oh well.

To celebrate this great achievement, I will put a bunch of videos with examples of organic compounds and how to name them. If that isn't ending the year with a bang, I don't know what is.

Ok, so after all that, you must ACTUALLY be a genius now, right?

More Functional Groups: Carboxylic Acids, Esters, Ethers, Amines

Carboxylic Acids, Esters, Ethers, and Amines

Carboxylic Acids

• They are parent chains with a double bonded oxygen and alcohol connected to the end.
• Name is changed simply by adding 'oic' to the end of the parent chains name followed by acid.
• For example: Butane = Butanoic acid

Beautiful Butanoic acid

Esters

• They contain two chains of hydrocarbons separated by an oxygen and double bonded oxygen.
• The parent chain with no double bonded oxygen will be named first and given the ending 'yl'
• The parent chain with the double bonded oxygen will have the ending 'oate'
• For example(picture):

They give off fruity smells.

Ethers

• They consist of 2 groups connected by an oxygen in the middle.
• The shorter group is named first and ends with an 'oxy' ex: methoxy
• The other group will remain the same.

Nice and simple, Methoxybutane

Amines

• They are parent chains with NH2 connected somewhere to it.
• For naming simply add 'yl' then amino. ex: methyl aminoethane

Basic structure of an Amine

Functional Groups: Halides, Nitro, Alcohols, Aldehydes, Ketones

Halides(Nitro), Alcohols, Aldehydes, and Ketones

Functional groups contain elements other than Carbon and Hydrogen. (ex: oxygen, flourine, alcohol, etc.)

Halides(Nitro)

• These can be attached to Alkanes, Alkenes, and Alkynes.
• They are Halogens: Fluoro, chloro, bromo, iodo, etc.
• To name Halides count the positions of the halogens connected to the parent chain.
• Remember, alphabetical order!

an example of a halide would be:

2-Chloro-3-fluoro-pentane

TNT is a Nitro.

Alcohols

• With alcohols the parent chain's name ends with an 'ol' ex: Ethanol
• Again, count the position of the alcohol connected to the parent chain

Here's propanol

Aldehydes

• They are double bonded oxygen connected to the end of the parent chain.
• When naming, the parent chain's end with an 'al' ex: Methanal

A simple methanal.

Ketones

• Basically the same as Aldehydes EXCEPT, the double bonded oxygen is connected in the middle of the parent chain.
• As usual the ending of the parent chain will change this time to 'one' ex: butanone

Glorious Butanone

Organic Chemistry: Naming + Alkanes, Alkenes, and Alkynes

All things organic need a name.

• The differences with each group is how the name ends, in this case Alkanes end with an 'ane'.

Methane!

• Depending on how many hydro Carbons there are the beginning of any name would start with:       -Methane, Ethane, Propane, Butane, Pentane, Hexane, Heptane, Octane, Nonane, and Decane. (these are also all Alkenes!)

A helpful little chart for naming groups of atoms.

Alkenes

• Just like Alkanes, Alkenes end with an 'ene'
• The difference with Alkanes is that it has a double bond somewhere in the chain.
• When counting Alkenes always make note that the double bond should be the lowest number infront of the parent chain.
• An example of an Alkene would be CH2=CH2, ethene

Examples of Alkenes.

Alkynes

• Just like the other two, Alkynes end with an 'yne'
• This time alkynes have a triple bond somewhere in the chain.
• Just like Alkanes, Alkynes should have the triple bond be the lowest number infront of the parent chain.
• An example of an Alkyne would be CH=CH, ethyne

Examples of Alkynes.

The Very Special/Valence Shell Electron Pair Repulsion Theory

The Valence Shell Electron Pair Repulsion Theory, or VSEPR, is a theory based upon the idea that

a. molecules take up three-dimensional space, obviously, and
b. that electrons repel one another.

The result is a series of diagrams which occur, given a certain number of bonded elements as well as unbonded pairs of electrons...

Such special geometric molecules can be specially named:

Where
A represents the central atom,
X# represents the number of outer bonded atoms,
and
E# represents the number of lone electron pairs.

Here is a table of different geometries of different chemical compounds you ought to know for our test!




If you find yourself, daring to ask why they form these interesting shapes. Don't worry, the answer is simple.  Because electrons repel each other in 3D space, each bonded or lone pair of electrons will simultaneously try to space themselves out to create the least amount of repulsion possible.

Watch the video if

a. you're extremely bored.
b. VSEPR Theory still confuddles you.
c. you want to watch a video that concisely demonstrates VSEPR in a way words and pictures cannot.

     

Quality Bonding Time

It's time for some... "Quality Bonding Time "!
And no that does not mean we are going to bond over a campfire with s'mores... (which quite frankly sounds preferable).

 

Instead, you, the mystery man/woman, looking at this post can read this blog regarding...

Chemical Bonding

... and bond with yourself.

Chemical Bonding occurs, in this universe, although not necessarily in parallel universes, in three different ways.


NUMBA 1: IONIC BONDING


This type of bond occurs between a metal and a non-metal.
The metal (positively charged) will give away some or all of its valence electrons to the non-metal (negatively charged) to create an EPIC neutral ionic compound between two or more atoms.



NUMBA 2: NON-POLAR COVALENT BONDING

Aka COVALENT BONDING will occur between two non-metals (negatively charged) and funnily enough usually between the same non-metals.  See what I just did there? You're bonding with yourself by reading this blog and the non-metals are also (often) bonding by themselves. MIND = BLOWN.  The two non-metals will come together to share some or all of their valence electrons to create an equally EPIC non-polar covalent compound between two or more atoms.


NUMBA 3: POLAR COVALENT BONDING

This bonding is sooooo similar to "NUMBA 2" but not quite... The only difference is that one side of the covalent bond is getting more of the action.  Meaning that the more electronegative / non-metalish atom will still share valence electrons with the less electronegative / non-metalish atom; however the electrons "like" non-metals better (apparently) and will therefore spend more of their time there.


DID YOU KNOW THAT???
A. I just made a Bill Nye - the Science Guy reference.
I. IONIC compounds have a very high melting point cause of their exceedingly mighty bonds
C. COVALENT compounds also have a very high melting point cause of their exceedingly mighty bonds but have a lower melting point because of the weaker bonds that hold multiple covalent compounds together.

Calculating Electronegativity Difference

Elements in the PT (Periodic Table) have specific electronegativities. Not sure what unobtanium's is though, probably because it's un-obtain-able. LOL.

Anywho, to calcuate the ELECTRONEGATIVITY DIFFERENCE (ENeg Diff.) use the simple formula:

Energy difference = Electronegativity 1 - Electronegativity 2.

Which will, ergo, tell you what kind of what kind of chemical bond is formed.  Sorry for blowing your mind, again!

SITUATION 1: The ENeg Diif. is less than 0.5 - which means the compound will form a Covalent Bond!

SITUATION 2: The ENeg Diff. is greater than or equal to 0.5 and less than or equal to 1.8 - which means the compound will form a Polar Covalent Bond!

SITUATION 3: The ENeg Diff. is greater than 1.8 - which means the compound will form an Ionic Bond!

"DUUUUUUDE, NARLY, DUUUUDE" - you must be saying.

BAZINGA!

If you're feelin' G and want to learn about bonds watch this vid:

Now, a quick recap on Lewis Diagrams. I know we learned this all last year, but how about a couple examples and diagrams, ok?

This is one of the most common, H2O, but something to notice is that it is bended. Hmmm....

You are probably thinking, "Oh great Chemistry King! How will I know if it is bended or not?"
'Well, young grasshopper, you'll just have to memorize this one." Words of wisdom.




Here's CO2 (yes. "X" is ok too):

Now, if all of that grade ten curriculum isn't coming flooding back to you, check out this video. She makes it look SO simple.

You go gurl. Like a boss.

What will make you richer, Ionic Bonds or Covalent Bonds? hehe

There are two kinds of chemical bonding:

Ionic Bonding and Covalent Bonding.

Ionic Bonding involves the bonding between a metal and a non-metal (or an element with a positive charge, and an element with a negative charge).  The positively charged metals will give away a certain number of electrons to negatively charged non-metals because of the strong attraction of the non-metal.

Observe and Learn:




Where as...

Covalent Bonding involves the bonding between non-metals and non-metals.  In this instance, the chemically bonding non-metals will share a certain number of valence electrons (electrons in the outer-most shell).




But remember kids, if in doubt google it out.

And voila, you may have found:

"All About Covalent Compounds" http://misterguch.brinkster.net/covalentcompounds.html

"All About Ionic Compounds" http://misterguch.brinkster.net/ionic.html

or better yet...

"Ionic and covalent bonding animation"

What's Trending on the Periodic Table these Days?

Fortunately, the many different trends of the periodic table are very unlike fashion trends which vary from year to year and season to season (which would make it exceedingly difficult for students).  Instead, periodic trends ironically tend not to trend (as in internet fads) and are certainly not very trendy.

However, they can certainly be somewhat interesting!

Ionization Energy: The amount of required energy to remove an electron from an atom (to create an ion).

Ionization energy will increase as it moves right across a period (row) because there are more protons which cause a greater pull on the electrons.  And it will decrease as it moves down a group (column) because the protons are farther away from the electrons energy shells and because of the shielding effect, or the repelling of electrons.

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                                                               i  

Atomic Radius: Quite simply the radius of an atom.

The atomic radius will decrease as you moves right across a period because of the increased attraction of protons.  But it will increase as you move down a group because each energy shell results in a larger distance to the nucleus.

     i

                                                                                 n

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Electra-negativity: Is an element's property as a non-metal to take in an electron; elements are more likely to do this when they have a negative charge. 

Electra-negativity tends to increase as you move right across a period because non-metals are located on the right side of the periodic table.  But it will decrease as you move down a group. Aside - chances are if it increases as you move right then it will decrease as you move down and vice versa!!!

                                                                                      y                                                                                                                          

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                                                                        a

                                                                      e

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                                                               i  

 

 

Density is mass per unit volume.

Give this a try yourself! Remember what density means and what causes atoms to become denser!

Here are some additional trends you may want to remember:

Atomic Size: It decreases as you move right across a period but increases as you move down a group.

Reactivity: It is lowest in the middle of the PT (periodic table and increases left downwards, and righ upwards.

The Melting point incrases as it approaches the centre of the PT.

Don't forget to try the...

Dynamic Perioidic Table - Ms. Chen approved

(it will help you experiment and learn different trends) : http://www.ptable.com/

Predicting the Number of Valence Electrons

Valence Electrons are all of the electrons which take part in reactions. They are also known as "Reactable Electrons". They are located in the outermost open shell of an atom. The highest  shell. In other words, if you had 6s24f145d106p2, you would only have 4 valence electrons, since you would only count the ones in the 6th orbital.


Here are some new terms to learn:
Open Shell: Shell containing less than the maximum number of electrons.
Closed Shell: Shell that contains exactly the maximum number of electrons.


So, in a nutshell (so punny, I know), valence electrons are all of the electrons in an atom except for the filled shell.
*Note: This excludes full d and f shells.

Don't you wish you were one of these shells instead
of learning about scientific shells? I digress.

Examples:
Sc = [Ar]4s23d1 = 2 Valance Electrons
Tl = [Xe]6s24f145d106p1 = 3 Valence Electrons (do not count full f and d shells)


All Noble Gases have 8 or 0 Valance Electrons. Whichever you prefer to write.


Now wasn't that quick and easy? Lovely. I don't even think that a video is needed... Jokes! Of course I have a video for you!

My favourite lady...

Energy and Orbit Levels

Today I will be telling you about the electronic structure of the atom.

Energy and Orbital Levels
All atoms have energy. Some, however, are higher than others. Atoms with a high energy state are said to be Hyperkinetic.When one or more electrons have energy levels greater than their lowest energy levels, which is also known as their Ground State,  they will jump to a higher orbital level. "n" represents the energy level.


I'll just tell you what a few words mean:
Excited State: This is when one or more electrons in an atom are in any energy level other than the lowest.
Orbital: This is the region of space that an electron occupies in an energy level.
Shell: This is the set of all orbitals having the same "n" value.
Sub-Shell: This is the set of orbitals of the same type.



There are four types of orbitals, that each contain a different amount of electrons. They are: s,p,d and f.

Here are the different amount of electrons possessed by each orbital of a given "n" value:

Level 1 (n=1): s 
Level 2 (n=2): s and p
Level 3 (n=3): s, p and d
Level 4 (n=4): s, p, s and f 

It is easy to remember how to fill the shells, if you write out this simple diagram to the left and put the diagonals in. There is a bit of a trick to it too which I will tell you about later... But first, let's try an example:

What is the electron configuration of the element Potassium in it's neutral state?
First, you have to figure out how many electrons there are in potassium. (39 - 19 = 20) Therefore, there are nineteen electrons.
Next, all you have to do is fill the orbitals until no electrons are left.

*Note: s can only carry 2 electrons. p can carry 6 electrons. d can carry 10 electrons. And, finally, f can carry 14 electrons.

Electron configuration for potassium:
1s22s22p63s23p64s1

Core notation can be used which is meant to simplify our configurations. Doesn't always work out that way, though...

Example:

What is the core notation for the element Calcium?
Calcium has 20 electrons, and if we write it's configuration, it would be 1s22s22p63s23p64s2.
To simplify it, we have to find the closest noble gas to calcium, without going over, of course. So, that would be Argon, which has 18 electrons. We then take out the first 18 electrons and replace it with [Ar]. Doing this makes the answer [Ar]4s2. This may be simple for an element like calcium, but if we were trying to do Arsenic, well, that is tricky.....

Of course, like everything in life, there are Principles and Rules that must be followed....

The Pauli Exclusion Principle

Wolfgang Pauli. This strapping, young lad to the left came up with a principle that explains how electrons are arranged in an atom. He theorized that, while protons and neutrons remain constant, electrons do not. Pauli said that a certain number of electrons can be put in each specific energy level.This has been proven true. This makes sure that all electrons do not go in the first energy level. He also thought that two electrons would not be able to take up the same  state in a closed system.

The Aufbau Principle
Pauli, with the help of Bohr, also came up with the Aufbau Principle. This principle stated that the lower energy levels should be filled before the higher ones. This is indeed the case.

The Hund's Rule

Friedrich Hund. Another fine, young speciemen that came up with yet another rule. He proposed a law that stated that every electron will pair up, but only  once the previous orbital is full. These electrons will pair up with other electrons with a similar amount of energy.

Now, onto that little trick I promised you earlier...

If you ever are having a hard time remembering the configuration, just look at your Periodic Table:

It is all laid out so beautifully for you! The electronic configuration is in it's proper rows and it has all the right numbers and everything. Makes it all easy as pie, doesn't it?

Now, where would we be without a video to finish us off? Here it is:

Lab 6D

A stoichiometry based lab that takes 2 days, a lab day and a results day.

Day 1- On this day it involved getting 25 mL of Na2CO3 solution and 25 mL of CaCl2 solution poured into one beaker. We observed. It looked like a thick milky solution.

We let the solution set aside and moved on to set up the ring stand, filtering apparatus, and beaker. We gingerly poured the solution bit by bit through the filter into to the beaker waiting below. There`s not much to do so we waited.

Once all of the solution drained we took the filter paper out and let it dry overnight until next class.

Day 2-  We weighed the mass of our filter paper and what we got from mixing the two reactants was:

1Na2CO3 + 1CaCl2 - 2NaCl + CaCO3

Basically salt and chalk

Percent Yield and Purity

First, let's look at Percent Yield.

Sometimes not all the product is recovered or all the reactants are not used up, so we calculate the Percent Yield. The basic formula is: amount of product obtained / amount of product expected X 100 to get percent.
Basically, when dividing the two numbers, if you get something over 1, something, somewhere, has gone terribly wrong...

Now let's use this info in an example:
15.0 g of CH4 reacts with excess Cl2 according to the following equation:
CH4 + Cl2 = CH3Cl + HCl
a total of 29.7 grams of CH3Cl is produced. What is the percentage yield?

First, we have to find the mass of CH3Cl that is expected:
15.0 g CH4 X 1 mol CH3Cl / 16.0g CH4 X 1 mol CH3Cl / 1 mol CH4 X 50.5 g CH3Cl / 1 mol CH3Cl = 47.34 g

Now let's figure out the percentage yield:
29.7 g / 47.34 g X 100 = 62.7 %
*Remember not to round until the end and use sig. figs.*

Simple enough, right? Let's do a backwards one to see if you really get it:
What mass of CuO is required to make 10.0 g of Cu according to the reaction:
2NH3 + 3CuO = N2 + 3Cu + 3H2O
if the reaction has a 58.0% yield?

We have to find the mass of CuO:
10.0 g Cu X 1 mol / 63.5 g Cu X 3 mol CuO / 3 mol Cu X 79.5 g CuO / 1 mol CuO = 12.52 g

Now, we have to divide this amount by 0.580 to get the LARGER number that will allow for the LOSS that will occur during the reaction:
12.52 g / 0.580 = 21.6 g


One more example:
What mass of K2CO3 is produced when 1.50 g of KO2 is reacted with an excess of CO2 according to the reaction:
4KO2 + 2CO2 = 2K2CO3 + 3O2
if the reaction has a 76.0% yield?

Calculate the mass of K2CO3:
1.50 g KO2 X 1 mol KO2 / 71.1 g KO2 X 2 mol K2CO3 / 4 mol KO2 X 138.2 g K2CO3 / 1 mol K2CO3 = 1.458 g

Now multiply that by the percent yield:
1.458 g X 0.760 = 1.11 g


Phew! Any more questions? Watch this video:

If you have this down, the next part will be easy.

What's more pure than a sparkly diamond?

Percentage Purity Time!

Only the pure part of a substance will actually react so sometimes we need to calculate the percentage purity of a substance.
The formula is basically the same as percentage yield: mass of pure reactant / mass of impure reactant X 100

Example:
If 100.0 g of FeO produces 12.9 g of pure Fe according to the reaction:
2FeO + 2C + O2 = 2Fe + 2CO2
what is the percentage purity of FeO used?

Same as before, find the mass of FeOl:
12.9 g Fe X 1 mol Fe / 55.8 g Fe X 2 mol FeO / 2 mol Fe X 71.8 g FeO / 1 mol FeO = 16.6 g

Calculate the percentage purity:
16.6 g / 100.0 g X 100 = 16.6 %


As you can see, everything is basically the same as percentage yield. Got it? Good. Have fun!

Excess and Limiting Reactants

This entry focuses more on the reactant side of a chemical equation
*aside: after all there's no reaction without them!!

A balanced equation assumes that there is a perfect amount of reactants in order for the reaction to occur; but it's theoretical. Say what?

In real life however, this is of course, impossible! In order for a reaction to occur there must be too much of one reactant to ensure that enough of the reactants will combine.

Therefore, one reactant will be fully used and be the limiting reactant (because it limits how much of the other reactant is reacted) and the other reactant will have some molecules left over and be the excess reactant.

The Four Steps to Success! OR The Four Steps to finding the excess reactant and its amount...

1. Write a balanced equation! Simple eh? If an equation is given but is unbalanced - balance it. And even if there is an equation that looks suspiciously balanced - check it anyway.

2. Convert each mass of the reactants to the mass of the same product.

3. Take the limiting reactant (the mass of the reactant that results in a smaller mass value of the product) and convert that into the excess reactant (the mass of the other reactant).

4. Subtract your accurately approximated and brilliantly solved for value from step 3 from the theoretical mass  given.

OR

Watch this video, if you prefer to have someone teach it vocally to you!

Voila!

YOU  CAN NOW FIND THE AMOUNT OF EXCESS REACTANT!!

 

I suppose you may want to test this theory for yourself,

Very well... Example 1!:

Okay seriously awkwardly dancing and cheering people cut it out!

A 2.00 g sample of ammonia is mixed with 4.00 g of oxygen.  Find which reactant is in excess and by how much. You may begin:


4 NH_3(g) + 5 O_2(g)4 NO_(g) + 6 H₂O_(g)











If your awesomeness is as above average as your IQ (or not) you may want to try a more advanced method.
This is of course assuming that you are a chemistry wiz (or not) and are more concerned about how much time you spend doing chemistry, then doing a slower and more certain process (or not). Well I can certainly see that you all fit the bill.

LET US PROCEED!


Example 2: 90.0 g of FeCl₃ reacts with 52.0 g of H₂S.  What is the limiting reactant?

2FeCl_{3 +} 3H₂S ---> 6HCl + 1Fe2S3


52.0 g H₂S x 1mole H₂S  x 2 moles FeCl_{3  x 162.3 g} FeCl_{3  =  165 g} FeCl₃
                            34.1 g H₂S     3 moles H₂S      1 mole FeCl₃ 


The limiting reactant is FeCl_3. 


This website, will help you to master your stoichiometry skills.  It has stoichiometry questions that involve every day situation too!

http://www.chemteam.info/Stoichiometry/Limiting-Reagent.htm

Stoichiometry Calculations

As previously mentioned... stoichiometry is calculations which involve chemical reactions!

Just in case you have forgotten what chemical reactions may look like (which i doubt ;) this will help!

From our studies with moles, we have learned quite a few different conversions which involve them.

This chart sums up mole conversions, before our virgin ears ever heard the word stoichiometry:




Stoichiometry simply adds one more step to this simple conversion chart.

In a balanced chemical reaction, once given the mass, particles or volume of either the reactant or product; a chemistry 11 student can then find the mass, particles or volume of any other reactant or product!

How is this possible?!

Well since we know how many moles of a certain substance per so many moles of another substance, we can use this as a conversion.

For example in the balanced chemical equation:

2 Fe + 3 Cl₂ = 2 FeCl_{3; 
where we know there are 123.4 grams of iron (Fe), we can find the amount of product, (FeCl3):}


123.4 g Fe x 1 mol Fe     x  2 mol FeCl3   x  162.3 g FeCl3  = 717.8 g FeCl3


                    55.8 g Fe        1 mol Fe              2 mol FeCl3

Remember this concept can be applied to any sort of calculation involving a reaction; given you remember some important facts!
                                          Such as: Volume at STP (22.4L), M = moles / litres


Here`s a website with in depth information, for our blog`s eager learners!

  http://www.shodor.org/unchem/basic/stoic/