SBI 4U Biochemistry - Molecular Polarity

Vocabulary flashcards covering intramolecular and intermolecular forces, bond electronegativity, water chemistry, and functional groups from Lesson 2 - Molecular Polarity.

Organic Molecules

Carbon-based molecules with typically hydrogen bonded to them, which can also include nitrogen, oxygen, phosphorus, and sulfur.

Intramolecular Forces

The forces within molecules that hold atoms together, which are usually chemical bonds, specifically covalent bonds.

Ionic Bonds

Bonds formed by electron transfer from a metal to a non-metal, resulting in positive ions (cations) and negative ions (anions).

Covalent Bonds

Bonds between two or more non-metals that involve sharing pairs of electrons, resulting in attraction between nuclei and shared valence electrons.

VSEPR Theory

Valence Shell Electron Pair Repulsion Theory; describes the shape of a molecule based on the number of bonding electron pairs and nonbonding pairs, where electrons aim to move as far away from each other as possible.

Polarity

A condition of unequally shared electrons in a bond or molecule caused by differences in electronegativity between atoms.

Electronegativity

The ability of an atom to attract a shared electron pair in a covalent bond.

Non-polar Covalent Bond

A covalent bond in which the electronegativity difference ($\Delta E_n$) between the bonded elements is between $0.0$ and $0.4$.

Polar Covalent Bond

A covalent bond in which the electronegativity difference ($\Delta E_n$) between the bonded elements is between $0.5$ and $1.6$.

Ionic Bond (Electronegativity Difference)

A chemical bond characterized by an electronegativity difference ($\Delta E_n$) greater than $1.7$.

Intermolecular Forces

Forces of attraction between molecules that influence physical properties such as melting point, solubility, and brittleness.

Van Der Waals Forces

Very weak attraction forces between all non-polar molecules caused by temporary unequal distribution of electrons.

Dipole-dipole Forces

Intermolecular forces stronger than Van Der Waals forces that hold polar molecules together when the positive side of one polar molecule attracts the partially negative side of an adjacent polar molecule.

Hydrogen Bonds

The strongest intermolecular forces, which are especially strong dipole-dipole forces between $H^+$ and $N^-$, $O^-$, or $F^-$ atoms of a neighbouring polar molecule.

Hydrophilic Molecules

Molecules that can dissolve in water due to their polar nature and natural tendency to form hydrogen bonds with water molecules.

Hydrophobic Molecules

Non-polar molecules that do not form hydrogen bonds with water and will not dissolve or mix with water.

Hydrophobic Effect

The natural clumping away of non-polar molecules from water molecules, which plays a central role in cell membrane formation and protein folding.

Functional Groups

Clusters of atoms attached to a central hydrocarbon chain of a molecule that give the molecule specific physical and chemical properties.

Hydroxyl Group

A polar functional group with the formula $-OH$, found in carbohydrates, proteins, nucleic acids, and lipids.

Carbonyl Group

A polar functional group with the formula $-COH$ (aldehyde) or $-C=O$ (ketone), found in carbohydrates and nucleic acids.

Carboxyl Group

A polar, acidic functional group with the formula $-COOH$ that donates a proton and is found in proteins and lipids.

Amino Group

A polar, basic functional group with the formula $-NH_2$ that accepts a proton and is found in proteins and nucleic acids.

Sulfhydryl Group

A slightly polar functional group with the formula $-SH$, found in proteins.

Phosphate Group

A polar, negatively charged functional group with the formula $-PO_4$, found in nucleic acids.

Structural Formulas

Two-dimensional representations that show how atoms are bonded together, where each line represents a single covalent bond.