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The central piece to all organic chemistry is the carbon atom. Just to review, carbon has 6 protons, its symbol is C, and it has an atomic mass of a little over 12. Organic chemistry focuses less on calculations and numbers, and instead on how carbon and the many compounds it make interact.
The first thing to review is the different types of bonds. Organic chemistry deals almost exclusively with covalent bonds. Covalent bonds occur between two non metals, the green and orange colored elements in the table above. Covalent bonds are by far the most complicated out of the three types. Next are ionic bonds. Ionic bonds form between metals, in blue, and non-metals. Lastly, metallic bonds form between two metals. In this course, we will deal exclusively with covalent bonds.
Valance electrons play an important role in organic chem. Before we cover Lewis structures in the next lesson, click here to watch a quick review on valance electrons.
Another basic topic in Organic Chemistry is the concept of Electronegativity, and its effect on bond polarity. Electronegativity is the pull that an atom has on an electron. Florine, near the top right corner has a high electronegativity, because it wants to fill its valance shell and become more stable. Francium, all the way across the table, has 1 excess electron. Therefore, the nucleus has a much weaker pull on the outer electron, and it has a low electronegativity.
When two atoms with differing electronegativities form a covalent bond, the more electronegative atom will pull more electrons to its side of the bond, making the new molecule polar. Use this model to see the effects of electronegativity on bond polarity.
Part of why bond polarities are important is because they impact inter-molecular forces. The IMF caused by a polar molecule is called dipole dipole interaction. Other intermolecular forces include London Dispersion Forces, and the strongest IMF, hydrogen bonding. These IMF's only occur in covalent bonds. All covalent bonds have London Dispersion Forces, which are very weak. However, specific circumstances are needed to have an atom preform hydrogen bonding.
In order to form a hydrogen bond, there must be:
A hydrogen atom attached to a very electronegative atom like nitrogen, oxygen, or fluorine
A second molecule with another highly electronegative atom
An open lone pair on the electronegative atom of the second molecule
The molecule that attracts the hydrogen is called the acceptor, and the molecule that shares a hydrogen is called a donor.
If you want to review hydrogen bonds any further, click here.
Do you know your basic chem? Take a quick quiz to make sure you're ready to move onto hybridization
Photos from: https://stock.adobe.com/images/carbon-big-on-periodic-table-of-the-elements-with-atomic-number-symbol-and-weight-with-color-delimitation-on-white-background-vector/141003126, https://sciencenotes.org/electronegativity-definition-and-trend/, https://revisionscience.com/a2-level-level-revision/chemistry-level-revision/bonding-and-structure/hydrogen-bonding
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