Chem Class - May 27, 2010

Esterfication Lab

-Today, we had the chance to synthesize an Ester from a carboxylic acid and an alcohol.

- We needed the following materials: isopropyl alcohol, methanol, salicylic acid, acetic acid, concentrated sulphuric acid, 2 x 200 mL beakers, ice water, eye droppers, and test tubes

- Remember that esterfication is the formation of an Ester from a carboxylic acid and an alcohol

- Esters are responsible for many common smells:
isoamyl acetate-----> banana
isobutyl salicylate-----> raspberry
methyl salicylate----->wintergreen
ethyl butyrate-----> pineapple
benzyl butyrate-----> cherry
ethyl propionate-----> rum
isopropyl acetate-----> perfume
benzyl acetate-----> peach
methyl butyrate----->apple
octyl acetate----->orange
propyl acetate-----> pear
ethyl phenylacetate-----> honey


- We decided to create a wintergreen smell (Alcohol = Methyl alcohol and acid = Salicylic Acid):
1) We used a hot plate to heat up about 150 mL of water in a beaker
2) We added one scoop of salicylic acid to a test tube
3) We added 15 drops of methanol to the same test tube
4) We added 2-4 drops of Sulphuric acid (Had to be careful however as sulphuric acid is very corrosive)
5) We placed the test tube in the hot water bath for 15 minutes and placed a 10 ml beaker over the test tube
6) We colled the test tube in the ice water bath for 2 minutes

7) We wafted the fumes toward our noses to carefully smell the test tube. Success! Wintergreen!

Chem Class - May 25, 2010

Today, we got into groups of 2 or 3 to build as many of the given molecules as we could in a given amount of time. After completing each model, we had to show it to Mr.Doktor. The first group to form them all got starbursts!

Here are the molecules we had to form:
1) Methyl butanoate
2) dichloroethane
3) 3 enthyl 2 pentanone
4) Acetic acid
5) dimethyl ether
6) ethyl propyl ether
7) 2 bromo 4,4 dimethyl pentanal
8) 2,3 pentadiol
9) ethylamide
11) 2, 2 dimethyl butylamide
12) propyl butanoate
13) Formaldehyde
14) Phenol
15) 3 choloro 3 methyl 2 butanone

Chem Class - May 20, 2010

- Went over our homework
- Finished off functional groups today

Amides
 - General group:  Double-bonded oxygen to carbon and NH2
- Naming: Use carbon prefix and -amide suffix
- Building block of proteins
-Nylon/Kevlar/Penicillin/LSD

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Amines
- Contains nitrogen with carbon chains (primary, secondar and tertiary/ remember that nitrogen can have up to three bonds)
- Make up amino acids (amine and carboxyclic acid)
- Naming: Alkyl prefix with -amine ending
- Two ways of naming: Example- Another way of saying methylamine is aminomethane

Now that we've finished learning about each of the functional groups, here's a video on them:

Chem Class - May 18, 2010

Today, we went over what we learned last class and went over our homework. After that, we continued with our notes on Functional Groups:

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Aldehydes
- Double bonded O, single bonded H at the end of a chain
Naming: change the -e ending to -al

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Carboxylic Acids
- Found in insect bites
- Building blocks of fats/seroids

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Ester
- found in flavoring, perfumes, cospectics, fruits, vegetables oil
- They are formed by esterfication of carboxylic acids
- Name the primary chain with -yl ending
- Secondary chain ends in -oate

The following is what an esterfication reaction looks like:

Chem Class - May 14, 2010

- Today, we were put into groups of four. Each team was assigned a specific type of organic chemistry group with examples. We were to come up with rules for naming them. Afterwards, we all came together and shared what we learned, taking down the following notes:

Functional Groups

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Halides

- Halogen atoms replace a hydrogen

- Bromo, Chloro, Floro

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Alcohols

- OH or hydroxyl group
- Change the ending to -ol

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Ketones
- Oxygen atom double bonded to carbon
- Change the ending to -one

Propanone (Acetone)

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Ethers
- Have an O joining two carbon chains together
- Name each carbon chain with -yl ending and add 'ether'

The following is the first part of a series of videos made by a student on the functional groups in organic chemistry:

Chem Class - May 10, 2010

Today, we went over homework and continued with our notes for the Unit:

Cyclo Alkanes
- Carbon compounds can form rings
- Follow the same naming rules and add cyclo- in front of the parent chain
- When numbering, you can count clockwise or counterclockwise, but where you start (#1) should be on one of the side chains because you are usi ng the lowest numbering system

Examples of Cyclo Alkanes:

Aromatics
- When a cyclic 6 carbon chain forms, it can create a resonance structure called Benzene

<---Benzene

Chem Class - May 4, 2010

- Today we went over our homeowrk and took the following notes:

Alkenes
- Compounds with double bonds end in -ene

- Put a # in front of the parent chain that indicates where the double bond is

- More thn one double bond changes the parent chain slightly

- Double bond always has priority (when choosing the direction of numbering)

- Any rime more than one double bond occurs, you add adi, atri, atetra...

- The longest chain has to include the double bond

Alkynes
- For compounds with triple bonds use -yne ending

- Follow all the same alkene rules

- The longest chain has to include the triple bond

Here's a video on naming and drawing three Aliphatics that we learned so far (ALkanes,Alkenes,Alkynes):

Chem Class- April 30, 2010

New unit:
ORGANIC CHEMISTRY
- There are more carbon compounds than all ionic compounds combined
- The study of carbon compounds is called organic chemsitry
- Carbon can have multiple bonds and form many different shapes

Hydrocarbons have three types of formulas:

1) Molecular formulas
C6H14

2) Condensed Structural Formula
CH3-CH2-CH2-CH2-CH2-CH3

3) Structural Formula

Nomenclature of Hydrocarbons
- One molecular formula can have a number of different structures
- Isomers are compounds that can be drawn in more than one way

Naming Alkanes
1) Name the longest chain by using the correct suffix and adding "ane"
2) Locate any branches by number carbon atoms (use the lowest possible number system)
3) Name branches by using appropriate suffix and -yl ending (Alkyl branches)
4) If there are more than one of the same alkyl group, number each one and add the multiplier number in front of the branch name

Chem Class - April 22, 2010

Ions in Solutions
- The formation of a solution depends on the ability of the solute to dissolve in the solvent
- Solvation is the interaction between solutes and solvents
- Ionic solids (salts) are cyrstals made up of ions
- Molecular solids are crystals made up of neutral molecules
- Dissolving ionic solutions produces ions in a process called disssociation (remember?)

Ionizaiton is the break up of a neutral molecule into charged particles
Examples:
1) FeCl3 (s) ----->Fe 3+ (aq) + 3 Cl -1 (aq)
2) Ag2O (s) -----> 2 Ag + (aq) = O 2- (aq)

3) Na3PO4(s) -----> 3 Na + (aq) + PO4 (aq)

4) (NH4)2SO4 (s) -----> 2NH4 + (aq) + SO4 2- (aq)

Determining concentrations is relatively easy.

Examples:

What is the [Cl-] in a solution of 0.50 M AgCl3?

AgCl3 -----> Ag + (aq) + 3Cl- (aq)
Cl = 3x as many moles = (0.5 M) x 3 = 1.5 M

What is the [NO3-] in a solution of 0.82 M Fe(NO3)2?
Fe(NO3)2 -----> Fe 2+ (aq) + 2 NO 3- (aq)
(0.82 M) x 2 = 1.64 M

What is the [Cr2O7 2-] and [K+] when 3.5 g of K2Cr2O7 dissolved in 40 mL of water?
K2CrO7 -----> CrO7 2- (aq) + 2K + (aq)
3.5 g x 1 mol/294.2 g = 0.0

Here is a video showing the dissociation of salt:

Chem Class - April 20, 2010

Intermolecular Bonds
- bonds between molecules
- 3 types

1) London Dispersion Force (L.D.F)
- Results from temporary electron dipoles
- Weakest intermolecular force
- Increases as the $ e- increases
- Occurs in any compound that has e- (ie: everything)

2) Dipole-Dipole
- Results from a permanent dipole in molecules
Polar molecules experience this force
Polarity depends how much elements want e- (electronegativity)
- Electronegativity increases to the right and up
- The strength of a dipole- dipole  bond depends on the difference in electronegativity between the two atoms
- Only polar molecules experience this

Substance          Boiling Point              # of e-
N2                     -196 degrees C          14
O2                     -183 degrees C          16
NO                   - 152 degrees C          15
ICl                       97 degrees C            70
Br2                     59 degrees C             70

(The more electons, the higher the boiling point. The type of intermolecular bond also plays a role.)

3) Hydrogen Bonnds (H-bonds)
-This is a special type of dipole- dipole bond between H and O, F, or N
- Any molecule that: H-F, H-O or H-N

Identify the substances with H-Bonds:
1) CH4
2) CH3OH
3) H2S
4) CH3-NH2
5) HCl
6) CH2-OH-OH2
       /      /       /
    OH  OH  OH

Answer: Number 2, 4, and 6

Compare the boiling points of:
- Ethanol (C2H5OH)
- Ehtane (C2H6)
- Methanol (CH3OH)
- Methane  (CH4)

The actual boilingpoints: Ehtanol = 78 degrees Celcius, Ethane= -89 degrees Celcius, Methanol = 65 degrees Celcius and Methane = 161 degrees Celcius. Remember London Forces are the weakest intermolecular force and hydrogen bonds are the strongest. Also, the more electrons, the higher the boiling point.

Chem Class - April 16, 2010

Today we...

- Went over our homework
- We did a lab based on 'polarity'
               - Before that, however, we did some notes:

Solvents and Solutes can be Polar or Non-polar
Non-polar substances have equal charge distribution (symmetrical)
Polar substances have an unequal charge distribution (asymmetrical)

H2O = polar:

CH4 = nonpolar:

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The lab's objective was to determine if Glycerin is polar or non-polar.

Here's the background information that was written on the lab:

- Sodium chloride is an ionic solid crystalk that forms a crystal lattice structure. When dissolved in solvents, this lattice breaks up and the ions dissociate.

- Sucrose is table sugar and like Sodium Chloride it also forms a crystal structure. Unlike Sodium Chloride however, Sucrose is not ionic; it is molecular. The structure of Sucrose makes the molecule polar.

- Iodine, like Sucrose, is molecular and also forms crystals. However the crystals of Iondine are non-polar.

- Water is a polar solvent

- Paint thinner is a non-polar solvent

- Glycerine is a polar solvent

The materials we needed were test tubes, test tube stoppers, a test tube rack, scupula, safety goggles and an apron, sodium chloride, sucrose, iodine crystals, paint thinner (Turpentine) and Glycerin

The entire procedure basically involved us seeing whether or not the solutes (like table salt, sugar and iodine) dissolved in the solvents (water and paint thinner). We learned that polar solutes dissolve in polar substances and non-polar solutes dissolved in non-polar substances (LIKE DISSOLVES LIKE)

Chem Class - April 14, 2010

Today we finished our test, and finished our conductivity lab by finding the conductivity of water. Distilled water on its own is not conductive, but as soon as we add salt (ions) the conductivity increases.

Electrical conduction in solutions requires charged ions to be present.
Ionic solutions dissociate (break apart) when placed in water. Molecular solutions do not usually split into ions
The following is the dissociation of sodium chloride:

Follow these steps to determine conductivity:
Is it a metal?
If yes it is conductive. If no ask...
Is it a solid non-metal?
If yes it is non-conductive. If no ask...
Is it an acid or base?
If yes it is conductive. If no ask...
Is it ionic?
If yes it is conductive. If no it is non-conductive.

Here is a video on electrical conductivity, demonstrating that ions must present in solution for electrical conductivity:

Chem Class - April 1, 2010

Today we had just enough time to do a lab that involved testing the conductivities of different solutions.
Here's our results (Just by looking at the table you can see that ionic solutions are more conductive than molecular solutions):

Chem Class- March 30, 2010

We can't believe we're already in Unit 6!

Solution Chemistry

- The study of chemical reactions in solutions

- A solution is a homogeneous mixture

- Solvents are components present in larger amounts

- Solutes are componets present in smaller amounts

- A solute is soluble in a solvent if it dissolves to form a homogenous mixture

- A saturated solution contains as much solute as possible

- An unsaturated solution can dissolve more solute

- Solubility is the measure of how much solute can dissolve in a given solution  (g/L, g/ml, mol/L, ppm)

- The solubility of Ba (NO3)2in water is 63 g/100 mL @ 25 degrees Celcius while the solubilty of Ba(NO3)2 in alcohol is is 1.6 g/ 100 mL @ 25 degrees Celcius

- Fators that can affect solubility: heat, changing the solvent and changing the solute

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Chem Class - March 26, 2010

We had an extremely short class today!
Here's some key points on electronegativity:

Electronegativity
- Atoms affinity for electrons
- Electronegativity increase from left to right and from bottom to top

- Polaritiy is the separation of charge inside something that is neutral

Chem Class - March 24, 2010

And so, we continue...

Covalent Bonding
- Electrons are shared between non-metals
- To draw Lewis Dot Diagrams:

1. Add the valence e- in all atoms
2. Identify which atom can form the most number of bonds. This will be the central atom
3. Bonds between two atoms are repesented by a line. This repesents 2e-.
4. Any e not creating bonds are placed in paris around the remaining atoms
5. All valence levels must be filled, all electrons must be used

Double and Triple Bonds
- Some compounds form more than one bond between two elements

(To the left of the element or compund is a Lewis Diagram and a Structural Diagram. You can see that there are sometimes two or three lines that separate the elements in the Structural Diagram. These represent the double and triple bonds.)

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For more help, this is a link that leads you to a geat little slide show on Lewis Dot Structures of Covalent bonds. It also gets you involved by having you type in the answers:
http://www.wisc-online.com/objects/ViewObject.aspx?ID=GCH6404

Chem Class - March 22, 2010

Back to Notes!

Atoms and Ions
- Atoms are electrically neutral
- # of protons = # of electrons
- Ions have a different number of protons and electrons
- Ions can either be positve (lose electrons) or negative (gain electrons)
- Cation = positive ion
- Anion = Negative ion

- Determine how many electrons each of the ions have and what type of ion they are:
Ca2+ = lost 2e-/cation
F- = gained 1 e-/anion
H+ = lost 1 e-/cation
Ag+ = lost 1e-/cation
H- = gained 1e-/anion
N3- = gained 3e-/ anion

- Determine how many protons, neutrons and electrons the following substances have:
76As3-/ p+ = 33/ n0= 43/ e- = 36
201Au+/ p+ = 79/ n0= 122/ e- = 78
56Fe3+/ p+ = 26/ n0= 30/ e- = 23

Bohr Diagrams for Ions
 - Draw the energy level or Bohr Diagram for the following ions:
Ca2+ 8e-/8e-/2e-
Li+ 2e-
F- 8e-/2e-
O2 8e-/2e-
P3- 8e-/8e-/2e-

Chemical Bonds
- A bond is an electrostatic attraction between particles
- Bonds occur as elements try to achieve Noble gas electron configuration
        - Noble gases (usually) do not form compounds or bonds
        - In Noble gases the outermost energy levels have stable octets

Lewis Dot Structures
- Atoms can be represented by dot diagrams
        - Dots represent electrons
        - Only valence electrons are shown
- Write the atomic symbol for the atom
             - This represents the nucleus and filled inner energy levels
- One dot is used to represent outer energy levles
         - One e- is placed in each orbital before any pairing occurs
         - Beginning with the 5th e-, pairing can occur up to a maximum of 8e-
- Below: Electron dot diagrams for different elements

Ionic Bonds
- Electrons are transferred from metal to non-metal
- No dots are shown on metal
- "Charged" species are written in brackets

- Example: Sodium Chloride




This video touches upon Ionic dot diagrams:

Chem Class - March 17, 2010

     THE CHEMICAL FAMILIES

     The vertical columns in the periodic table are known as groups or chemical families. There are five groups: Alkali Metals, Alkaline Earth Metals, Transition Metals, Halogens and Noble Gases. Hydrogen is actually in a separate group on its own. Elements in the same chemical family have similar physical and chemical properties.

     The Alkali Metals are in group 1 of the Periodic Table (points). IT includes Lithium, Sodium, Potassium, Rubidium, Cesium, and Francium. Elements in this family are highly reactive and reactivity increases as you go down the group. These metals have only one electron in their outer shell and so, they are always ready to lose that one electron in ionic bonding with other elements. They react readily with non-metals such as oxygen and water, and usually have lower densities than other metals. They also are malleable, ductile, good conductors of heat and electricity and have low melting points, all of which are below 200 °C. Finally, alkali metals are soft and can actually be cut with a knife.

     Elements in the second column are part of the Alkaline Earth Metal family. This includes Beryllium, Magnesium, Calcium, Strontium, Barium and Radium. They have two electrons in their outer shell and have low electronegativities. They are also less reactive than Alkali Metals but they will burn in air if heated. They will also react with water. They are all metals with a shiny, silvery white colour.

    

     The Transition Metals are the 38 elements in groups 3-12 of the periodic table. They are very hard, have high melting and boiling points, low ionization energies, high electrical conductivity and are malleable, which means that they are able to be shaped and bent.

     The Halogens are in group 17 of the periodic table. They are Fluorine, Chlorine, Bromine, Iodine, and Astatine. They are highly reactive non-metals with strong and unpleasant odours. In addition, they will burn flesh and do not react well with water. Fluorine and chlorine are gases at room temperature, Bromine is a liquid and Iodine and Astatine are solids.

     The last family is the Noble Gases, found in group 18 of the Periodic Table. They include Helium, Neon, Argon, Krypton, Xenon and Radon. The Noble Gases are the most stable and unreactive elements in the periodic table. They are colourless, odourless gases at room temperature. They also have high ionization energies and low boiling points.

Chem Class- March 15, 2010

We started presenting our projects today. Here's one group's perspective:

We made a poster board of Mendeleev teaching it to us on a blackboard, and our information would slide out from it. Elements are arranged by atomic number, not atomic mass because each element has different isotopes that all have different masses but have the same atomic number. We also gave our quiz orally to the class.

Mendeleev's Periodic Table
- 1867, a Russian chemist and teacher, Dmitir Meneleev started organizing every known element and is credited with creating the first real periodic table of elements

- He discovered a pattern and left holes in the table for elements that had yet to be discovered

- There are 118 elements in the Periodic Table as of March, 2010

- There are 7 periods and 18 columns

- Metals are on the left and non-metals are on the right

- Elements with similar properties fall into vertical columns

- Atomic Number: Number of protons of the nucleus of each atom of an element

- Atomic Mass: Mass of an average atom of an element (tends to increase along with atomic number)

- Ion charge: Electric charge that forms on an atom when it gains or loses electrons

Mendeleev's Periodic Table

Modern Periodic Table

Chem Class- March 9, 2010

We got a group project assigned today. We are to provide a summary on one of the following topics:

• Mendeleev's Periodic Table
• Metals
• Non-metals
• Metalloids
• Trends n Physical Properties of Elements on the Periodic Table
• Trends in chemical properties of elements on the periodic table (ion charge, chemical reactivity, ionization energy)
• Properties of Alkalis, Alkaline Earth Metals, Halogens, Noble Gases and Transition Metals

- The information is to be put on a poster. In addition, a handout and quiz is to be handed out to the class.

Chem Class- March 5, 2010

Emission Spectra
-Each element gives off a specific colour of light
- These are known as emission spectra
             - Unique to each element
             - Astronomers make use of this to find out which elements
               a star is composed of
- If electrons absorb energy they can be bumped to a higher level
- When they fall to a lower level they release that energy as light

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Atomic Structure
- Atoms are made up of parts called subatomic particles (protons, neutrons and electrons)

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Atomic Number

- Atomic Number = number of protons

 

A = atomic number/ B = Ion charge/ C = Symbol/

D = Element name/ E = Atomic Mass

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Isotopes
- The nymber of protons determine the type of element
- Changing the number of neutrons changes the isotopes of the element
- All isotopes have the same chemical properties

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Mass Number

- Mass number is the total of protons and neutrons

- Symbol given is A

- Different isotopes have different masses

- Mass number = atomic number + number of neutrons

A = Z + N

Let's say you're given the Isotope of 54-Fe. The mass would be 54, the atomic number would stay the same as it is given in the periodic table (26), the number of protons would be 26 (same as the atomic number) and the number of neutrons would be 28 (mass number - atomic number).

Try 14-C
Mass = 14/ Atomic number = 6/ Number of protons = 5/ Number of neutrons = 8


Here's a video on Isotopes as well as the Atomic Mass:

Chem Class- March 3, 2010

BOHR MODEL
- Atoms are electrically neutral
- Two different models can be used to describe the electron configuartion: Energy Level Model and Bohr Model- Electrons occupy orbitals: 2e in the first orbital, 8e in the second orbital (octet)and 8e in the third orbital (octet)


The video is very detailed. It explains the Bohr Model and it’s origin. So far we’ve only grazed the surface... So it’s fine to just ignore the formulas and specifics. The video does explain the Development of the Bohr Model, how electrons give off energy and briefly explains why Rutherford’s atomic model is defective.



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For the element Argon the Energy level model would look like this:
8e- 3rd level
8e- 2nd level
2e- 1st level

40
18 Ar   <-----the top number is the atomic mass and the bottom number is the atomic number or number of protons)

It's also good to note that the number of electrons is equal to the number of protons in a neutral atom, and the number of neutrons is equal to the atomic mass - the number of protons.

The Bohr model diagram for the element Argon would look like this:

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For the element Chlorine the Energy level model would look like this:

7e- 3rd level
8e- 2nd level
2e- 1st level

35
1 Cl

The Bohr model diagram for the element Chlorine would look like this:

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For the element Fluorine the Energy level model would look like this:

 7e- 2nd level
2e- 1st level

19
9 F


The Bohr model diagram for the element Chlorine would look like this:

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Orbital Shapes

- Atomic orbitals each have a specific name and shape

The atomic orbital on the left is 1s and the atomic orbital on the right is 2s. Notice that 2s is just bigger.

               Notice that the ps have the same shape that they are orientated differently (x is along the x axis, y is along the y-axis and z is along the z axis)
















Hybridized Orbitals
- The first of the Bohr levels is the 1st orbital and it holds 2e

- The second level contains 2s, 2px, 2py, 2pz orbitals. They combine (hybridize) to form one 2sp3 orbital.