UNC Chemistry Organic Compounds Experiment Reflection Essay

Using robust details and ample evidence, create a reflection essay that describes 4 learning objectives you met while performing this experiment.

Virtual Lab Manual
Carbon Valence, Hybridization and Angles
Synopsis
Get your hybridization right! In this simulation, you will learn why the element carbon forms
four chemical bonds to be in a stable state. You will explore the involved valence electrons
and their orbitals, and how hybridization is key to forming equal, stable bonds.
Organic chemical compounds
You will start off by meeting with Simon, who’s having trouble figuring out the ins and outs of
the fundamentals within organic chemistry. Try to resolve his confusion about what, exactly,
is meant by ‘organic’. Perhaps you will be able to sort him out?
Dive into the orbitals
In the lab, you join forces with Dr. One, who will support and test you on your mission. After
getting suited up for being in the lab, and getting a quick briefing on organic compounds, you
jump into a virtual animation on the valence and orbitals of carbon. You’ll need to pay close
attention, as Dr. One will quiz you afterwards! Should you be in trouble, you can always jump
over to the theory pages for help in finding the correct answer.
Getting the bond angles right
Now that you’re prepped with the fundamental knowledge of carbon bonds, it will be time to
put it all into action. Move on to the holotable, where you will be challenged with figuring out
the placement of hydrogens in common organic compounds, factoring in double and triple
bonds.
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Returning to Simon
Armed with all your new knowledge, you will return to Simon to share all you’ve learnt. It’s a
tricky topic though, but luckily you can repeat the experience if you want to drive the points
in even further. Will you be able to solve the carbon hybridization challenge?
Learning Objectives
At the end of this simulation, you will be able to…
● Give examples of uses of organic compounds
● Identify the carbon valence electrons and the hybridization of their orbitals
● Predict the angles of covalent bonds in hydrocarbons
Techniques in Lab
None
Theory
The nature of organic compounds
Organic chemistry is the study of organic compounds and their structure, properties, and
reactions. Organic compounds are chemicals that are based on the element carbon, and
most often they would also contain bonds between carbon and hydrogen. Methane, a
hydrocarbon, shown in Figure 1, is one of the simplest organic compounds.
Figure 1: Structure of methane, a simple organic compound.
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Many organic compounds contain elements other than carbon and hydrogen, typically oxygen
and nitrogen, but it can also be other groups such as phosphorus or halogens.
Some carbon compounds are not considered to be organic, e.g. carbonates and carbon oxides
like carbon monoxide and carbon dioxide. These types of compounds are regarded as
inorganic.
Hydrocarbons
Hydrocarbons are a subgroup of organic compounds, which contain only carbon and
hydrogen. Examples of hydrocarbons can be seen in Figure 2.1. Salicylic acid, shown in Figure
2.2, is an organic compound, but it’s not a hydrocarbon as it contains oxygen groups.
Figure 2.1: Structure of the hydrocarbons methane, propane, and 1-butene.
Figure 2.2: Structure of salicylic acid, which is an organic compound but not a hydrocarbon.
Electrons of carbon
A carbon atom has 6 electrons, arranged in the configuration 1s² 2s ² 2p ². The 2 electrons in
the 1s orbital are not of interest in organic chemistry, as they do not partake in the reactions
involved here. The remaining four electrons are the carbon atoms valence electrons, as these
are available for forming covalent bonds. From the electron configuration, you would expect
carbon to only form two bonds, but due to orbital hybridization, carbon can meet the octet
rule of having eight electrons in its outer shell.
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The octet rule
The octet rule states that atoms combine to obtain eight electrons in their outer shell.
Hydrogen atoms, which often seek to have 2 electrons in their outer shell, are a notable
exception.
Orbital hybridization
Orbital hybridization is the mixing of the outer shell orbitals in an atom in order for it to be
able to complete the octet rule. For carbon, this means that the electrons in the 2s, 2pₓ, and
2pᵧ combine to form new, equivalent orbitals. If the carbon atom only forms single bonds, sp³
hybridization produces four equal orbitals. If a double bond is formed, sp² hybridization
produces three equal orbitals, with a single 2p orbital left to form the second part of the
double bond. If a triple bond is formed, sp hybridization produces 2 equal orbitals, with two
2p orbitals left to form the second and third part of the double bonds.
When carbon forms bonds with hybridized orbitals, the bond is a σ (sigma) bond. The bonds
formed with unhybridized orbitals for the remaining part of double or triple bonds are called
π (pi) bonds.
Carbon bond angles in organic compounds
The angles between the bonds in organic compounds depend on the hybridization and
therefore the types of bonds formed by each of the carbon atoms. If only single bonds are
present, the angle between each of these is 109.5°. If a double bond is formed, the angle
between the bonds is 120°, and if a triple bond is involved, the angle is 180°. See Figure 3 for
examples of the angles described above. The angles of the bonds have important
implications for which products are formed in chemical reactions involving organic
compounds.
Figure 3: Organic compounds showing how the angles of the compound depend on the bonds
it forms.
Nomenclature of simple hydrocarbons
Simple hydrocarbons are named based on a few straightforward rules. The first part of the
name – the prefix – is determined by the number of carbon atoms in the longest carbon
chain. The second part of the name – the suffix – is determined by whether double or triple
bonds are present. A visual representation of these principles can be seen in figure below.
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Figure 4: Overview of the nomenclature principles of simple hydrocarbons.
If more than one location is possible for a double or triple bond, a number is added to
indicate its placement on the carbon chain, always counting from one end of the chain and
giving the carbon the lowest number possible.
Hydrocarbon prefixes
Prefixes for simple hydrocarbons are determined by the number of carbon atoms in the
longest carbon chain. Figure 5 shows the general principle of assigning prefixes regardless of
the type of bonds involved in the compound.
Figure 5: Role of the prefixes in names of hydrocarbons.
List of hydrocarbon prefixes
The following table shows the prefixes for hydrocarbons with 1-10 carbon atoms present in
the longest carbon chain. Note that only the prefix is shown in the second column and that
the whole name includes the suffix, which for hydrocarbons depend on whether double or
triple bonds are present in the compound.
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Table 1. List of prefixes in names of hydrocarbons and examples of complete names.
NUMBER OF CARBON ATOMS
1
2
3
4
5
6
7
8
9
10
PREFIX
MethEthPropButPentHexHeptOctNonDec-
COMPOUND EXAMPLE
Methane
Ethene
Propyne
1-Butene
Pentane
3-Hexyne
2-Heptene
Octane
1-Nonyne
4-Decene
Hydrocarbon suffixes
Suffixes for simple hydrocarbons are determined by the type of bonds present. See figure
below which suffixes apply.
Figure 6: Overview of hydrocarbon suffixes
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