Section 2.1: Chemistry Foundations for Biology 3

Vocabulary flashcards covering the key chemistry and water-related concepts from the notes, including atoms, bonds, ions, solutions, and pH.

Element

The simplest form of matter; defined by its atomic number; 91 elements exist; six are most abundant in humans: oxygen, carbon, hydrogen, nitrogen, calcium, phosphorus.

Atomic number

Number of protons in an atom's nucleus; identifies the element.

Proton

Positively charged particle located in the nucleus.

Neutron

electrically neutral particle located in the nucleus.

Electron

Negatively charged particle surrounding the nucleus; outer-shell electrons are valence electrons.

Nucleus

Center of the atom containing protons and neutrons.

Atomic mass unit (amu)

Unit used to express atomic and molecular weights; mass equals number of protons plus neutrons.

Isotope

A variant of the same element with a different number of neutrons but the same number of protons.

Radioisotope

A radioactive, unstable isotope that decays and emits radiation.

Ion

A charged particle (atom or molecule) with unequal numbers of protons and electrons.

Cation

Positively charged ion (more protons than electrons).

Anion

Negatively charged ion (more electrons than protons).

Ionization

Transfer of electrons from one atom to another.

Salt

An inorganic compound formed by the reaction of an cation and anion (e.g., NaCl); soluble in water and electrically neutral.

Electrolyte

Substance that ionizes in water to form a solution that conducts electricity; important for nerve and muscle function.

Inorganic vs Organic

Inorganic: compounds without carbon; Organic: compounds that contain carbon.

Mineral

Inorganic element or compound; calcium and phosphorus are minerals important for bones and enzyme function.

Calcium

Mineral important for bones, nerves, and muscles.

Phosphorus

Mineral important for bones and nucleic acids.

Hydrogen

Lightest element; in water as H in H2O; participates in acid-base chemistry.

Oxygen

Major element of life; highly electronegative; essential in organic molecules.

Carbon

Central element in organic molecules; forms diverse structures.

Nitrogen

Key element in amino acids and nucleic acids.

Sodium chloride (NaCl)

Common salt; an ionic compound (salt) composed of Na+ and Cl−; dissolves readily in water.

Ionic bond

Bond formed by electrical attraction between cation and anion; can be broken by water.

Covalent bond

Bond formed by sharing one or more pairs of electrons between atoms.

Polar covalent bond

Covalent bond with unequal sharing of electrons, producing partial charges (e.g., water).

Nonpolar covalent bond

Covalent bond with equal sharing of electrons; no partial charges (common in lipids).

Hydrogen bond

Weak attraction between a slightly positive hydrogen and a negatively charged atom (O or N) in another molecule; crucial in water and biomolecules.

Van der Waals forces

Brief, weak attractions between neutral atoms due to transient electron distribution.

Water (H2O)

Polar covalent molecule; universal solvent; participates in adhesion, cohesion, surface tension, and chemical reactions.

Solvent

The dissolving medium in a solution; water is the universal solvent.

Solute

Substance dissolved in the solvent.

Hydrophilic

Substance that dissolves in water (water-loving).

Hydrophobic

Substance that does not dissolve in water (water-fearing).

Solution

Homogeneous mixture where solute particles are small and evenly distributed in the solvent (usually water).

Colloid

Mixture with larger particles that scatter light and remain cloudy; larger than a solution but smaller than a suspension.

Suspension

Mixture with large particles that settle out; e.g., blood cells in plasma.

Emulsion

Suspension of one liquid in another, often requiring an emulsifier (e.g., oil in water).

Mixture

Substances physically blended but not chemically bonded; components retain properties.

pH

Negative logarithm of the hydrogen ion concentration; scale 0–14; 7 is neutral;

Acid

Substance that donates a proton (H+) in water.

Base

Substance that accepts a proton or donates hydroxide (OH−) in water.

Buffer

Chemical system that resists changes in pH by neutralizing added acids or bases.

Hydrolysis

Reaction where water breaks chemical bonds; adds water to split molecules.

Dehydration synthesis

Reaction that forms a bond by removing water; builds larger molecules.