Organic Chemistry CH. 1

Ochem unit 1 concepts

Ions

Atoms that have lost or gained an electron. “Moving particles”.

Cation

A positive ion (lost an electron). A moving particle that goes to the cathode.

Anion

a negative ion (gained an electron). An ion that goes to the anode.

(Constitutional) Isomers

Different substances that have the same elemental composition (same formula, different structure). “Same parts.”

hook-eye model

A common model for how small particles could cling together.

Hydrogen

“bringer of water”

Oxygen

“Bringer of acids”

Halogen

“Bringer of salts”

Stoichiometry

the representation of the process of keeping inventory of weights, and then atoms.

Balanced equation

the number of “molar equivalents”. These relationships express 1. the ratio or amounts of substances that are needed for a reaction according to the stoichiometric ratio in the balanced equation. 2. the ratio of reactants used under the experimental conditions, which might. be different from te stoichiometric ratio in the balanced equation. 3. The prediction of what is needed and/or what is missing can be identified to balance the equation.

Main group elements

groups 1 and 2 (s-block elements), groups 13-18 (p-block elements)

Valence

the “combining power” or value of an atom

Closed shell/uncharged atoms

number of protons = number of electrons. Atoms have valence shell filled.

Connectivity

the particular bonding arrangement of atoms in a given molecule. A description of which atoms are bonded to one another.

Hypervalent Structures

Expanded octet structures

Radical

Unpaired electron - a single electron sitting alone in an orbital. Represented as a single dot with nothing next to it.

Site of reactivity

A part of a molecule where reactions typically go through analogous changes among chemical formulas.

duet rule

a first row element has a 2-electron closed shell configuration.

Formal Charge

If an atom in a molecule claims the same number of electrons as in its atomic state, where the number of electrons equals the number of protons, then the formal charge is zero (an uncharged atom).

Saturated Structure

Products that did not yield any more addition of elements to the organic molecule.

An organic structure made up of only single bonds and no rings.

Unsaturated Structures

Can undergo addition reactions until the point at which it is saturated.

Electronegativity

Negatively charged electrons are attracted to the positively charged nucleus by an electrostatic force. A measure of how relatively attracted a given electron is to its nucleus.

Ionic compounds

Nonmetal and Metal. Is driven by transferring their valence electrons to other elements and achieving closed shell electron configurations.

Drawn completely isolated from one another and with valence shells filled. (unless it is charged)

Non-polar Covalent Bonds

If two atoms are identical, the two nuclei attract the shared electrons equally.

Drawn like in lewis structures.

Polar Covalent Compounds

If the two atoms are not identical, the two nuclei attract the shared electrons unequally. The electrons being held closer to the more positive (more electronegative) nucleus.

Drawn with partial positives added.

Unit of Unsaturation

Each two-hydrogen atom loss, with reference to the number of hydrogen atoms in the saturated hydrocarbon.

Formulas: CnMmDdTt

u.u = “2n + 2” - “m” + “t”

or

u.u = (2C + 2 + N - H - X)/2

C = n of carbons

N = n of Nitrogens

X = n of Halogens

H = n of Hydrogens

or

Count the number of rings and double bonds.

Heteroatom

any atom other than carbon or hydrogen in an organic molecule.

Curved arrow notation

A powerfully useful notational system to represent the bonding changes taking place during a proposed reaction mechanism. The curved arrow begins at the electron source and points to its destination. It doesn’t refer to the transfer or relocation of an atom, but rather, the transfer or relocation of electrons.