The Chemical Basis of Life: Atoms, Molecules, and Water

These flashcards cover key vocabulary and definitions related to the chemical basis of life, focusing on atoms, molecules, and water.

Atom

The smallest functional unit of matter that forms all chemical substances.

Atomic Number

The number of protons in an atom, which also equals the number of electrons in a neutral atom.

Ion

A charged atom or molecule that has gained or lost one or more electrons.

Isotope

Different forms of the same element that have the same number of protons but different numbers of neutrons.

Covalent Bond

A chemical bond formed by the sharing of electrons between atoms.

Polar Covalent Bond

A type of bond where electrons are shared unequally between atoms, resulting in partial charges.

Ionic Bond

A chemical bond formed by the electrostatic attraction between oppositely charged ions.

Hydrophilic

Substances that readily dissolve in water, often due to polar or ionic bonds.

Hydrophobic

Substances that do not dissolve in water, typically nonpolar molecules.

pH Scale

A measure of the concentration of hydrogen ions in a solution, ranging from 0 to 14.

Buffer

A solution that resists changes in pH when acids or bases are added.

Valence Electrons

Electrons in the outermost shell of an atom that are available for bonding.

Molarity

A way to measure concentration, defined as the number of moles of solute per liter of solution.

Free Radical

A molecule that has an unpaired electron, making it highly reactive.

Hydrogen Bond

A weak bond formed when a hydrogen atom covalently bonded to an electronegative atom is attracted to another electronegative atom.

Specific Heat

The amount of heat energy needed to raise the temperature of a substance by 1 degree Celsius.

Molecule

Two or more atoms bonded together.

Compound

A substance composed of two or more different elements chemically bonded together.

Octet Rule

The principle that many atoms are most stable when they have 8 electrons in their outermost shell.

Electronegativity

A measure of an atom's ability to attract shared electrons in a covalent bond.

Solvent

The substance, usually a liquid, in which a solute is dissolved to form a solution.

Solute

The substance that is dissolved in a solvent to create a solution.

Cohesion

The attraction between molecules of the same substance, such as water molecules sticking together.

Adhesion

The attraction between molecules of different substances, such as water sticking to a plant stem.

Acid

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

Base

A substance that decreases the concentration of hydrogen ions (H^+) in a solution, often by releasing hydroxide ions (OH^-).

Neutral pH

A solution with a pH of 7, where the concentrations of hydrogen ions (H^+) and hydroxide ions (OH^-) are equal.

Logarithmic Nature of pH

A property where each unit change on the pH scale represents a 10-fold change in the concentration of H^+ ions.

Logarithmic Formula for pH

The mathematical expression used to determine pH: pH = -\log_{10}[H^+].

Relationship between H^+ and pH

As the concentration of hydrogen ions (H^+) increases, the pH value of the solution decreases.