Structure and Bonding in Organic Chemistry

This set of vocabulary flashcards covers the fundamental concepts of chemical bonding, atomic orbitals, electron configuration, and carbon hybridization as presented in the lecture notes.

Chemical bond

The force that holds the atoms together in a molecule.

Molecules

Clusters, groups, or combinations of atoms that result from atoms of elements combining for existence.

Electropositive element

An element whose atoms give up electrons readily; these are generally metals.

Electronegative element

An element whose atoms gain electrons; these are generally non-metals.

Atomic orbital

A three-dimensional region or space around the nucleus of an atom where there is the highest probability of finding an electron.

s orbital

An atomic orbital that is spherically shaped; its size increases as the shell number increases (e.g., $1s$ is smaller than $2s$).

p-orbital

An atomic orbital that is dumbbell shaped and can be oriented along the x, y, or z axes ($p_x$, $p_y$, $p_z$).

Planar node

The area through the nucleus of the bulbs in a p-orbital representing the area of zero probability of finding an electron.

Electron configuration

The arrangement of electrons in the atomic orbitals of an atom.

Hund's Rule

A rule stating that electrons occupy all orbitals of a given orbital type singly before pairing begins.

Core electrons

Electrons located in the inner most shells of an atom.

Valence electrons

Electrons in the outer most energy level of an atom that can take part in chemical bonding.

Lewis symbol

A symbol consisting of an element’s symbol and surrounding dots to represent the number of valence electrons.

Electronic theory of valence

Also known as the octet theory of valence, it states that atoms interact by electron transfer or sharing to achieve a stable outer shell of eight electrons, similar to a noble gas.

Sigma bond ($\sigma$)

A strong, unreactive bond formed when orbitals containing valence electrons collide head on.

Pie bond ($\pi$)

A weaker, more reactive bond formed when orbitals collide side ways or laterally.

Organic chemistry

The study of the chemistry of compounds of carbon and hydrogen, along with other non-metals such as nitrogen, oxygen, and halogens.

Hybridization

The mixing of atomic orbitals with different characters, such as s and p, from the same shell to create new orbitals.

Promotion

A preparatory procedure before bonding where an electron, such as one from the $2s$ orbital, is excited to an empty $2p$ orbital.

Alkanes ($sp^3$ hybridization)

Compounds where four atomic orbitals (one s and three p) are hybridized to give four equivalent hybrid orbitals in a tetrahedral arrangement with angles of $109.5^\circ$.

Alkenes ($sp^2$ hybridization)

Compounds where three atomic orbitals (one s and two p) are hybridized to give three equivalent hybrid orbitals in a trigonal planar arrangement.

Alkynes ($sp^1$ hybridization)

Compounds where two atomic orbitals (one s and one p) are hybridized to form two hybrid orbitals, resulting in a linear structure.