Lesson 2: Essential Chemistry for Biology

Vocabulary flashcards defining core terms from Lesson 2: Essential Chemistry for Biology.

Covalent bond

A type of strong chemical bond in which two atoms share one or more pairs of valence electrons.

Molecule

Two or more atoms held together by covalent bonds.

Covalent bond (Polar & Non-polar)

Non-polar covalent bonds involve equal sharing of electrons between atoms, whereas polar covalent bonds involve unequal sharing due to differences in electronegativity.

Ionic bond

A chemical bond resulting from the attraction between oppositely charged ions formed by the transfer of electrons.

Ionic Compound

A compound composed of positive and negative ions held together by ionic bonds, also known as a salt.

Hydrogen bond

A weak chemical bond formed when a slightly positive hydrogen atom covalently bonded to one electronegative atom is attracted to another electronegative atom.

van der Waals interactions

Weak attractions between molecules or parts of molecules that result from transient local partial charges.

Chemical reaction

The making and breaking of chemical bonds, leading to changes in the composition of matter.

Reactants

The starting materials in a chemical reaction.

Products

The resulting materials formed by a chemical reaction.

Cohesion

The binding together of like molecules, often by hydrogen bonds, such as water molecules sticking to each other.

Adhesion

The attraction between different kinds of molecules, such as water molecules adhering to cell walls.

Surface tension

A measure of how difficult it is to stretch or break the surface of a liquid.

Specific heat

The amount of heat that must be absorbed or lost for $1\,g$ of a substance to change its temperature by $1\,^\circ\text{C}$.

Heat of vaporization

The quantity of heat a liquid must absorb for $1\,g$ of it to be converted from a liquid to a gas.

Evaporative cooling

The process in which the surface of an object becomes cooler during evaporation as the molecules with the highest kinetic energy escape.

Solute

A substance that is dissolved in a solution.

Solvent

The dissolving agent of a solution, usually the liquid component present in the greater amount.

Aqueous solution

A solution in which water is the solvent.

Hydrophilic

Having an affinity for water; hydrophilic substances are polar or ionic and interact well with or dissolve in water.

Hydrophobic

Having no affinity for water; hydrophobic substances are non-polar and tend to repel or not dissolve in water.

Acid

A substance that increases the hydrogen ion ($H^+$) concentration of a solution.

Base

A substance that reduces the hydrogen ion ($H^+$) concentration of a solution.

pH

A measure of hydrogen ion concentration defined as the negative logarithm (base 10) of the hydrogen ion concentration ($pH = -\log[H^+]$).

Buffer

A substance that minimizes changes in the concentrations of $H^+$ and $OH^-$ in a solution by accepting or donating hydrogen ions.

Hydrocarbon

An organic molecule consisting entirely of carbon and hydrogen atoms.

Functional group

A specific configuration of atoms attached to the carbon skeleton of organic molecules that participates in characteristic chemical reactions.