DOC PREVIEW
UT Arlington CHEM 2321 - Organic chemistry notes

This preview shows page 1 out of 3 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 3 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 3 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

Organic chemistry is the Study of: Carbon, Nitrogen, Oxygen, Hydrogen, Sulfur, Phosphorus and the Halogens- Substances are defined by a specific arrangement of atoms. They can contain different set of atoms, which is automatically understood as a different molecule, or they can have the same set of atoms but vary in the molecular structures, this is called Constitutional isomers.Constitutional isomers: have the same molecular formula, but differ in the way the atoms are connected. They differ in physical properties and names.Valency: is the number of bonding partners that an element can have.Hydrogen – mono valentCarbon – tetra valentNitrogen – tri valentOxygen – di valentFlourine – mono valentValence electrons: are the electrons in the outer most shell of an atom.- As two atoms of the same charge are brought in together, the force of repulsion between the negatively charged nuclei, the force of repulsion between the positively charged nuclei and the force of attraction between the positively charged nuclei and the negatively charged electrons allget stronger. For example Hydrogen.- As two of the same atoms come closer to each other, the bond length decreases and the energy is at a minimum. However as they are brought closer together the energy shoots up, making them repel. Lewis Dot structure: a way to model out electrons with their valence electrons.Ex. As shown in the diagram, Carbon has 4 valence electrons and hydrogen has 1. So as they come together and share the electrons, they form a stable organic molecule called methane (CH4). It also satisfies what is called the Octet rule.What are bonds: bonds are what are made when valence electrons of each atom are either shared (covalent) or transferred (ionic) between eachother.Types of Bonding:1. Ionic bonds (coulombic interaction) – electrons are transferred and happens only between meta and non – meta atoms2. Covalent bonds – electrons are shared and happens only between a non- metal and a non – metal atom. 3. Polar covalent bonds – electrons are shared but the electronegativity of the entire molecule is under consideration (leads to polarity)Lone pairs: a pair of electrons occupying an orbital in an atom or molecule and not directly involved in bonding. Ex.Octet rule: is when the outer most shell of each of the central atom is stable and adds up to 8 electrons.Electronegativity: is a measure of the ability of an atom to attract electrons. It increases as you move across the periodic table from left to right and from bottom to top.Electronegativity and Bonds:1. Ionic bonds: if the electronegativity is > 1.72. Polar covalent bonds: if electronegativity is between 0.5 and 1.7 (0.5 < EN < 1.7)3. Covalent bonds: if the electronegativity is < 0.5How to measure Electronegativity: electronegativity is measured by subtracting the electronegativity of the central atom with the electronegativity with that of the surrounding atom. Valence Bond theory: bonding between two atoms is caused by the overlap of half – filled atomic orbitals, such as sigma and pi bonds.Molecular orbital theory: molecular orbitals derive from atomic orbitals. As 1s orbitals come together they create a lower energy sigma bond (ex. H)Orbital: it is a region of space that can be occupied by electron density.Electron density: the probability of finding an electron in a particular region of space.- There are 4 types of orbitals: S,P,D,FAtomic orbital: an occupied “cloud of electron density”, it must be said as such because it is being referred to the nucleus of a single atom.- The nitrogen here has two electrons on top that are not pairs with a hydrogen, these are called lone pair electrons. - They play a significant role in VSEPR bond theory as they have forces of their own that push away bond pairs to some angle. Thus creating a specific shape tothe molecule as a whole.Hybridization theory: - 2s orbital is a sphere and 2p orbital is a dumbbell (a vertical dumbbell is an orbital in the y – axis,a horizontal one is an orbital in the x – axis and a diagonal orbital is in the z - axis).- s has 1 orbital consisting 2 electrons, p has 3 orbitals consisting 6 electrons, d has 5 orbitals consisting 10 electrons and f has 7 orbitals consisting 14 electrons. - The s orbitals are occupied first (this is the Aufbau principle), and the electrons that occupy them are at the lowest energy level. Next level occupied will be the p orbitals with a higher amount of energy than the s orbitals. It keeps going as electrons fill up the d orbital and then thef orbital. - Each orbital contains ONLY two electrons of opposite spins.- CH4 is a tetrahedral molecule: the bond angle between the 2hydrogens is 109.5⁰. - CH3 is a trigonal planar: the bond angle between the hydrogens is 120⁰.Steric number: the number of bonding partners and the number of lone pairs.Steric #4 – hybridization: sp3 (there is bonding in all four directions, or bonding in three, two sides with the rest being a lone pair).Steric #3 – hybridization: sp2 (there is bonding in only 3directions).Steric #2 – hybridization: sp (there is bonding in only 2directions).CH4 – sp3, tetrahedral, Charge: 0BF3 – sp2, trigonal planar, charge: 0NH4+1 – sp3, tetrahedral, charge: +1H2C=CH2 – sp2, trigonal planar, charge: 0OH-1 – sp3, linear, charge: -1H3O+1, sp3, trigonal pyramidal,charge:


View Full Document

UT Arlington CHEM 2321 - Organic chemistry notes

Documents in this Course
Load more
Download Organic chemistry notes
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Organic chemistry notes and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Organic chemistry notes 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?