Chemical Level of Organization

Vocabulary flashcards covering chemistry principles, atomic structure, chemical bonds, reactions, inorganic molecules, and organic macromolecules based on OpenStax Human Anatomy lecture notes.

Element

A pure substance that cannot be created or broken down by chemical means, with $92$ occurring naturally in the environment.

Compound

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

Atom

The smallest quantity of an element that retains the unique properties of that element.

Protons

Positively charged subatomic particles ($\text{p}^+$) located in the nucleus of an atom.

Neutrons

Neutral subatomic particles located in the nucleus of an atom.

Electrons

Negatively charged subatomic particles ($\text{e}^-$) located within the electron cloud surrounding the nucleus.

Atomic Number

The total number of protons in the nucleus of an atom.

Atomic Mass

The sum of the number of protons and neutrons in the nucleus of an atom.

Isotopes

Different forms of an element that have the same number of protons ($\text{p}^+$) but differing numbers of neutrons.

Radioactive Isotopes

Unstable isotopes containing extra neutrons ("heavy isotopes") whose nucleus decays, releasing subatomic particles and electromagnetic energy.

Octet Rule

The principle stating that atoms are most stable when there are exactly $8$ electrons ($\text{e}^-$) in their valence shell.

Chemical Bond

An electrical attraction that holds atoms in the same vicinity.

Molecule

A structure formed when two or more atoms bond together, which can belong to the same or different elements.

Ion

An electrically charged atom formed when an atom gains or loses electrons to achieve stability.

Cation

A positively charged ion formed when an atom loses electrons.

Anion

A negatively charged ion formed when an atom gains electrons.

Ionic Bond

A chemical bond formed by the electrical attraction between a cation and an anion after electrons are transferred.

Covalent Bond

A strong chemical bond formed between atoms that share electrons.

Polar Molecule

A molecule with a slightly positive end and a slightly negative end resulting from unequal sharing of electrons in covalent bonds.

Hydrogen Bond

A weak attraction between the slightly positive hydrogen end of a polar molecule and the slightly negative end (such as fluorine, oxygen, or nitrogen) of another polar molecule.

Kinetic Energy

Energy that matter possesses because of its motion.

Potential Energy

Energy that matter possesses because of its positioning or structure.

Chemical Energy

A form of potential energy stored in chemical bonds between atoms and molecules.

Reactants

The starting materials in a chemical reaction, such as atoms, ions, or molecules.

Products

The substances formed at the end of a chemical reaction.

Synthesis Reaction

A chemical reaction in which a more complex chemical structure is formed, represented by $A + B \rightarrow AB$.

Decomposition Reaction

A chemical reaction in which chemical bonds are broken to form a simpler chemical structure, represented by $AB \rightarrow A + B$.

Exchange Reaction

A chemical reaction in which bonds are broken and new bonds are formed, represented by $AB + CD \rightarrow AD + CB$.

Reversible Reaction

A chemical reaction in which the products can change back into the reactants, represented by $A + B \rightleftharpoons AB$.

Inorganic Compounds

Substances that do not contain both carbon and hydrogen, such as water, salts, acids, and bases.

Organic Compounds

Carbon-based substances that contain both carbon and hydrogen, including carbohydrates, lipids, proteins, and nucleic acids.

Dehydration Synthesis

A reaction that links monomers together by removing an $\text{OH}$ group from one monomer and an $\text{H}$ atom from another, releasing a water molecule.

Hydrolysis

A reaction that breaks down linked monomers by adding a water molecule, attaching an $\text{OH}$ group to one monomer and an $\text{H}$ atom to the other.

Cohesion

The phenomenon in which collective hydrogen bonds hold water molecules together.

Adhesion

The attraction between water molecules and other types of molecules.

Solution

A liquid that consists of a homogeneous mixture of two or more substances.

Solvent

The dissolving agent within a solution.

Solute

The substance that is dissolved in a solution.

Hydrophilic

Refers to polar covalent molecules that interact well with or dissolve in water.

Hydrophobic

Refers to non-polar covalent molecules that do not dissolve in water.

Salts

Compounds formed by ionic bonds that dissociate into ions other than $\text{H}^+$ or $\text{OH}^-$ when dissolved in water.

Electrolytes

Salt ions capable of conducting an electrical current in solution.

Acids

Substances that release hydrogen ions ($\text{H}^+$) into a solution.

Bases

Substances that release hydroxyl ions ($\text{OH}^-$) into solution or accept existing $\text{H}^+$ ions.

pH Scale

A measurement scale indicating the concentration of $\text{H}^+$ ions in a solution.

Buffers

Solutions composed of a weak acid and its conjugate base that neutralize small amounts of acids or bases in body fluids.

Carbohydrates

Water-soluble organic molecules made of carbon, hydrogen, and oxygen in a $1:2:1$ ratio that serve as the main source of cellular energy.

Monosaccharides

Single sugar units, including hexoses (glucose, fructose, galactose) and pentoses (ribose, deoxyribose).

Disaccharides

Double sugars consisting of two bonded monosaccharides, such as sucrose, lactose, and maltose.

Polysaccharides

Complex carbohydrates made of chains of monosaccharides, such as starch, glycogen, and cellulose.

Lipids

Organic hydrocarbon chains insoluble in water but soluble in organic solvents, including triglycerides, phospholipids, and steroids.

Triglycerides

The most abundant lipids in the body, composed of $1$ glycerol molecule attached to $3$ fatty acid chains.

Saturated Lipids

Lipids containing only single carbon-carbon bonds, typically solid at room temperature and derived from animals.

Unsaturated Lipids

Lipids containing one or more carbon-carbon double bonds, typically liquid at room temperature and derived from plants.

Phospholipids

Lipids composed of $1$ glycerol, $2$ fatty acids, and $1$ phosphate group that form cell membranes.

Steroids

Lipids characterized by $4$ connected carbon rings, with cholesterol being the primary example in the body.

Proteins

Organic compounds composed of amino acid building blocks used as structural components, energy sources, hormones, receptors, enzymes, and antibodies.

Amino Acid

The fundamental building block of proteins, consisting of an amino group ($-\text{NH}_2$), a carboxyl group ($-\text{COOH}$), and a unique R side chain.

Peptide Bond

A chemical bond formed between the amino group of one amino acid and the carboxyl group of an adjacent amino acid.

Primary Structure

The linear sequence of amino acids in a polypeptide chain.

Secondary Structure

The pleated or twisted arrangement (alpha-helices and beta-pleated sheets) created by hydrogen bonding between nonadjacent amino acids.

Tertiary Structure

The unique three-dimensional folded shape of a protein.

Quaternary Structure

The structure formed when two or more polypeptide chains connect together to function as one protein.

Denaturation

The disruption of protein shape and loss of function caused by broken chemical bonds from extreme heat, radiation, electricity, or pH changes.

Nucleic Acids

Large organic molecules composed of nucleotides that carry genetic code (DNA) or assist in protein synthesis (RNA).

Nucleotides

The structural building blocks of nucleic acids, consisting of a sugar, a phosphate group, and an organic base.

DNA (Deoxyribonucleic Acid)

A double-stranded chain of nucleotides containing deoxyribose sugar that stores genetic code.

RNA (Ribonucleic Acid)

A single-stranded chain of nucleotides containing ribose sugar that interacts with DNA to conduct protein synthesis.

ATP (Adenosine Triphosphate)

An energy molecule consisting of adenine, ribose, and three phosphate groups that releases energy for cellular processes when high-energy chemical bonds are broken.