Chapter 2: Atoms, Ions, and Molecules — Video Vocabulary Flashcards

Vocabulary-style flashcards covering key terms from the lecture notes on matter, atoms, bonds, water, mixtures, and biomolecules.

Matter

Substance that has mass and occupies space; exists in solid, liquid, or gas forms.

Atom

The smallest unit of an element that retains its chemical properties.

Element

Substance that cannot be broken down into simpler substances by ordinary chemical methods.

Periodic Table

Organizes all known elements by increasing atomic number.

Atomic Number

Number of protons in the nucleus of an atom.

Atomic Mass (Mass Number)

Total number of protons and neutrons in an atom.

Proton

Positively charged subatomic particle in the nucleus (1 amu).

Neutron

Electrically neutral subatomic particle in the nucleus (1 amu).

Electron

Negatively charged subatomic particle orbiting the nucleus; very small mass.

Nucleus

Center of the atom containing protons and neutrons.

Electron Shell/Energy Level

Region around the nucleus where electrons reside; filled by energy rules.

Valence Electron

Electron(s) in the outermost electron shell that participate in bonding.

Isotope

Atoms of the same element with different numbers of neutrons.

Carbon-12/13/14

Carbon isotopes with 6 protons; differ in neutrons.

Half-Life

Time required for half of a radioactive substance to decay; biological half-life differs.

Molecule

Two or more atoms bonded together.

Compound

A molecule composed of two or more different kinds of atoms.

Diatomic Molecule

Molecule consisting of two atoms of the same or different elements (e.g., H2, O2, N2).

Ions

Atoms with net electric charge due to gain or loss of electrons.

Cation

Positively charged ion.

Anion

Negatively charged ion.

Ionic Bond

Electrostatic attraction between oppositely charged ions in a lattice.

Salt

Ionic compound formed from cations and anions (e.g., NaCl).

Covalent Bond

Bond formed by sharing electrons between atoms.

Single Bond

Covalent bond with one pair of electrons shared.

Double Bond

Covalent bond with two pairs of electrons shared.

Triple Bond

Covalent bond with three pairs of electrons shared.

Carbon Skeleton

Arrangements of carbon atoms in chains or rings that form the framework of most organic molecules.

Nonpolar Covalent Bond

Electrons shared equally; little to no electronegativity difference.

Polar Covalent Bond

Unequal sharing of electrons; creates partial charges.

Electronegativity

Attraction of an atom for electrons in a bond; varies across periodic table.

Polarity

Presence of partial charges (positive and negative) in a molecule.

Amphipathic

Molecule having both polar (hydrophilic) and nonpolar (hydrophobic) regions.

Hydrogen Bond

Weak attraction between a partially positive hydrogen and a partial negative atom.

Hydrophilic

Water-loving; dissolves in water.

Hydrophobic

Water-fearing; does not dissolve in water.

Hydration Shell

Water molecules surround and interact with dissolved ions or molecules.

Organic Molecules

Carbon-containing compounds that are typically associated with living organisms.

Inorganic Molecules

Molecules lacking carbon-hydrogen skeletons (e.g., water, salts, acids, bases).

Water (H2O)

Polar molecule with two hydrogens and one oxygen; forms hydrogen bonds.

Cohesion

Attraction between like water molecules.

Adhesion

Attraction between water and other substances.

Surface Tension

Cohesive forces at the surface of a liquid that make it behave as if covered with a film.

Acid

Substance that dissociates to release H+ (proton donor).

Base

Substance that accepts H+ (proton acceptor).

pH

Measure of hydrogen ion concentration; 0-14 scale with 7 neutral.

Buffer

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

Mixture

Combination of two or more substances that are not chemically bonded.

Suspension

Heterogeneous mixture with large solutes that settle out.

Colloid

Mixture with smaller particles than a suspension; remains mixed.

Solution

Homogeneous mixture of solute dissolved in solvent.

Molarity

Moles of solute per liter of solution.

Carbohydrates

Biological macromolecule class; includes monosaccharides, disaccharides, polysaccharides.

Monosaccharide

Simple sugar monomer (e.g., glucose, fructose, galactose).

Glycogen

Stored glucose in liver and muscle via glycogenesis.

Glycogenesis

Synthesis of glycogen from glucose.

Glycogenolysis

Breakdown of glycogen to glucose.

Nucleic Acids

DNA and RNA; store and transfer genetic information.

Nucleotide

Nucleic acid monomer consisting of a sugar, phosphate, and a base.

Adenine

Purine base found in DNA and RNA.

Guanine

Purine base found in DNA and RNA.

Cytosine

Pyrimidine base found in DNA and RNA.

Uracil

Pyrimidine base found in RNA (replaces thymine).

Thymine

Pyrimidine base found in DNA (paired with adenine).

DNA

Deoxyribonucleic acid; double-stranded molecule storing genetic information.

RNA

Ribonucleic acid; single-stranded molecule involved in gene expression.

ATP

Adenosine triphosphate; primary energy currency of the cell.

Proteins

Macromolecules that catalyze reactions, provide structure, transport, and defense.

Amino Acid

Monomer of proteins; contains amino group, carboxyl group, and unique side chain (R).

Peptide Bond

Covalent bond linking amino acids during dehydration synthesis.

Primary Structure

Linear sequence of amino acids in a protein.

Secondary Structure

Repeating patterns like alpha helices and beta sheets in proteins.

Tertiary Structure

Three-dimensional folding of a protein into a functional form.

Quaternary Structure

Arrangement of two or more polypeptide chains in a protein.

Denaturation

Unfolding of a protein's structure, often irreversible, due to heat or pH.