Matters, Elements, & Atoms Lecture – Vocabulary Review

A comprehensive set of vocabulary flashcards covering fundamental chemistry concepts, biological molecules, and chemical reactions presented in the Chapter 2 lecture.

Matter

Anything that occupies space and has mass.

Mass

The amount of matter in an object; unaffected by gravity.

Weight

An object’s mass combined with the pull of gravity.

Element

A substance that cannot be created or broken down by ordinary chemical means.

Compound

A substance composed of two or more different elements joined by chemical bonds.

Atom

The smallest unit of an element that retains that element’s properties.

Proton

Heavy, positively charged subatomic particle located in the nucleus.

Neutron

Heavy subatomic particle with no charge located in the nucleus.

Electron

Negatively charged subatomic particle with nearly no mass orbiting the nucleus.

Atomic Number

Number of protons (and therefore electrons) in an atom’s nucleus.

Mass Number

Sum of an atom’s protons and neutrons.

Isotope

Atoms of the same element with equal protons but different neutrons.

Radioactive Isotope

Unstable isotope that emits radiation as it decays (e.g., Carbon-14).

Electron Shell

Region around the nucleus where electrons are likely to be found.

Valence Shell

The outermost electron shell involved in chemical bonding.

Molecule

Two or more atoms covalently bonded together.

Free Radical

Atom, molecule, or ion with at least one unpaired valence electron.

Acid (Chemistry)

Compound that releases hydrogen ions (H⁺) in solution.

Base

Compound that accepts hydrogen ions (H⁺) in solution or releases OH⁻.

Antioxidant

Chemical that protects cell membranes from free-radical damage.

Ion

Atom or molecule with an overall positive or negative charge.

Cation

Positively charged ion.

Anion

Negatively charged ion.

Ionic Bond

Electrostatic attraction between a cation and an anion.

Covalent Bond

Chemical bond formed by sharing electrons between atoms.

Single Covalent Bond

Bond in which one pair of electrons is shared.

Double Covalent Bond

Bond in which two electron pairs are shared.

Triple Covalent Bond

Bond in which three electron pairs are shared.

Hydrogen Bond

Weak attraction between a hydrogen atom and an electronegative atom; important in water, DNA, proteins.

Kinetic Energy

Energy of motion.

Potential Energy

Stored energy due to position or structure.

Chemical Energy

Potential energy stored in chemical bonds.

Exergonic Reaction

Chemical reaction that releases more energy than it absorbs.

Endergonic Reaction

Chemical reaction that absorbs more energy than it releases.

Mechanical Energy

Sum of kinetic and potential energy used to move objects.

Radiant Energy

Energy transmitted as electromagnetic waves (e.g., sunlight).

Electrical Energy

Energy supplied by moving charged particles (electrolytes) in body fluids.

Reactant

Substance that enters a chemical reaction.

Product

Substance produced by a chemical reaction.

Synthesis Reaction

Reaction in which smaller components join to form a larger molecule (A + B → AB).

Decomposition Reaction

Reaction that breaks a molecule into smaller parts (AB → A + B).

Exchange Reaction

Reaction involving both synthesis and decomposition (A + BC → AB + C).

Inorganic Compound

Substance lacking both carbon and hydrogen together (e.g., H₂O, NaCl, CO₂).

Organic Compound

Substance containing both carbon and hydrogen.

Polar Molecule

Molecule with partial positive and negative charges; water is an example.

Solution

Homogeneous mixture of solute molecules dissolved in a solvent.

Colloid

Mixture with clumps of molecules large enough to scatter light but not settle.

Suspension

Mixture in which particles settle out over time.

Buffer

Solution of a weak acid and its conjugate base that resists pH change.

Functional Group

Specific group of atoms within a molecule that reacts as a unit.

Hydroxyl Group

–OH functional group; polar; participates in dehydration and hydrolysis.

Carboxyl Group

–COOH functional group found in fatty acids and amino acids.

Amino Group

–NH₂ functional group found in amino acids.

Methyl Group

–CH₃ functional group often found in amino acids; non-polar.

Phosphate Group

–PO₄²⁻ functional group found in phospholipids and nucleotides.

Carbohydrate

Organic molecule composed of C, H, O; commonly called sugars.

Monosaccharide

Simple sugar and basic carbohydrate monomer (e.g., glucose).

Disaccharide

Sugar formed by two monosaccharides via a glycosidic bond (e.g., sucrose).

Polysaccharide

Polymer of many monosaccharides (e.g., starch, glycogen, fiber).

Glycosidic Bond

Covalent bond joining two monosaccharides.

ATP (Adenosine Triphosphate)

Energy-carrying molecule that releases energy when phosphate bonds break.

Hyperglycemia

Abnormally high blood glucose level; hallmark of diabetes mellitus.

Hypoglycemia

Abnormally low blood glucose level.

Triglyceride

Lipid made of glycerol plus three fatty acids; main energy reserve and insulation.

Phospholipid

Lipid with a phosphate group and diglyceride; major membrane component.

Steroid

Lipid characterized by four fused hydrocarbon rings (e.g., cholesterol, sex hormones).

Prostaglandin

Lipid signaling molecule involved in inflammation, stomach protection, airway dilation, and temperature regulation.

Fatty Acid

Long hydrocarbon chain with a carboxyl group; building block of lipids.

Peptide Bond

Covalent bond linking two amino acids via dehydration synthesis.

Amino Acid

Protein building block containing amino and carboxyl groups plus a side chain.

Protein

Polymer of amino acids folded into specific three-dimensional structures for diverse functions.

DNA (Deoxyribonucleic Acid)

Nucleic acid that stores genetic information.

RNA (Ribonucleic Acid)

Nucleic acid that helps convert genetic code into proteins.