Quiz Review

Element

A substance that cannot be broken down into simpler substances by chemical reactions.

Atom

The smallest unit of matter that retains all properties of an element.

Molecule

Two or more atoms held together by covalent bonds.

Compound

Two or more different elements combined in a fixed ratio.

Proton

A subatomic particle with a positive charge (+1).

Neutron

A subatomic particle with no charge (0).

Electron

A subatomic particle with a negative charge (-1) that determines an atom's overall charge and chemical reactivity.

Atomic Number

The number of protons in an atom.

Mass Number

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

Isotope

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

Radioactive Isotope

Unstable isotopes whose nuclei decay spontaneously, releasing particles and energy.

Valence Shell

The outermost electron shell of an atom.

Valence Electrons

Electrons in the valence shell available for chemical bonding.

Covalent Bond

The sharing of a pair of valence electrons by two atoms.

Electronegativity

An atom's attraction for shared electrons in a covalent bond.

Nonpolar Covalent Bond

A bond where electrons are shared equally or nearly equally due to similar electronegativity.

Polar Covalent Bond

A bond where electrons are shared unequally due to differing electronegativity.

Ionic Bond

A bond resulting from the complete transfer of electrons from one atom to another.

Cation

A positively charged ion formed by losing electrons.

Anion

A negatively charged ion formed by gaining electrons.

Hydrogen Bond

A noncovalent attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Van der Waals Interactions

Weak, transient attractions between adjacent molecules caused by temporary local partial charges.

Cohesion

The attraction between identical water molecules via hydrogen bonding.

Adhesion

The attraction between water molecules and other polar or charged substances.

Hydration Shell

A sphere of water molecules surrounding dissolved ions.

Hydrophilic

Substances with an affinity for water, typically polar or ionic.

Hydrophobic

Substances that repel water, typically nonpolar or nonionic.

Specific Heat

The amount of heat required to change the temperature of a substance.

Functional Groups

Specific chemical groups attached to carbon skeletons that participate in chemical reactions or modify molecular function.

ATP (Adenosine Triphosphate)

The primary energy-transferring molecule in cells, consisting of adenosine attached to three phosphate groups.

Nucleotide

The building block of nucleic acids, comprising a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Amino Acid

The building blocks of proteins, linked by peptide bonds to form polypeptide chains.

Denaturation

The loss of a protein's native 3D structure and function due to changes in temperature, pH, or salt concentration.

Isomer

Compounds with identical molecular formulas but distinct structural arrangements and properties.

Single Bond

A covalent bond formed by sharing $1$ pair of valence electrons between two atoms.

Double Bond

A covalent bond formed by sharing $2$ pairs of valence electrons between two atoms.

Surface Tension

A measure of how difficult it is to stretch or break the surface of a liquid, facilitated in water by hydrogen bonding.

Evaporative Cooling

The reduction in temperature of a liquid's surface as the molecules with the highest kinetic energy transition into the gas phase.

Organic Compound

A chemical compound containing carbon covalently bonded to other elements.

Hydrocarbon

An organic molecule consisting entirely of carbon and hydrogen atoms.

Structural Isomer

Compounds that have the same molecular formula but differ in the covalent arrangement of their carbon skeletons.

Cis-Trans Isomer

Compounds that have the same covalent bonds but differ in the spatial arrangement of atoms around an inflexible double bond.

Nonpolar Covalent Electronegativity Difference Range

An electronegativity difference ranging from $0.0$ to $0.4$.

Polar Covalent Electronegativity Difference Range

An electronegativity difference ranging from $0.4$ to $1.8$.

Ionic Electronegativity Difference Range

An electronegativity difference greater than $1.8$.

Thermal Energy

The total kinetic energy associated with the random motion of atoms or molecules in a given volume of matter.

Temperature

A measure of the average kinetic energy of the molecules in a body of matter.

ATP Breakdown Reaction

ATP —> ADP + Pi + energy

Estradiol vs. Testosterone Functional Groups

Estradiol contains a hydroxyl group ($-OH$), whereas testosterone contains a methyl group ($-CH_3$) and a carbonyl group ($C=O$).

Structural Difference and Receptor Binding of Steroids

Estradiol and testosterone share a common four-ring carbon skeleton but differ in attached chemical groups, enabling them to bind to distinct biological receptors.

ATP (Adenosine Triphosphate)

The primary energy-transferring molecule in cells, consisting of adenosine attached to three phosphate groups.

ATP Hydrolysis Reaction

$$\text{ATP} \rightarrow \text{ADP} + \text{P}_i + \text{energy}$$

Amino Acid Structure

A central carbon atom covalently bonded to an amino group ($-NH_2$), a carboxyl group ($-COOH$), a hydrogen atom, and a variable $R$ group.

Peptide Bond

The covalent bond formed between amino acids to build a polypeptide chain.

Spatial Distribution of Amino Acid R Groups

Nonpolar (hydrophobic) $R$ groups cluster inside the protein, whereas polar and charged (hydrophilic) $R$ groups face the outer aqueous environment.

Primary Protein Structure

The unique linear sequence of amino acids in a polypeptide chain.

Secondary Protein Structure

Localized folds, such as $\alpha$-helices and $\beta$-pleated sheets, stabilized by hydrogen bonds along the polypeptide backbone.

Tertiary Protein Structure

The overall three-dimensional shape of a single polypeptide, stabilized by interactions among variable $R$ groups.

Quaternary Protein Structure

The structural complex formed by the aggregation of two or more polypeptide chains.

Denaturation

The unraveling of a protein's native three-dimensional structure due to changes in heat, pH, or salt concentration, leading to loss of function.

Molecular Cause of Sickle-Cell Anemia

A single amino acid substitution in the primary structure of hemoglobin.

Biological Function of Nucleic Acids

Macromolecules responsible for storing, transmitting, and expressing genetic information in living organisms.

Nucleotide Components

A $5$-carbon sugar, a phosphate group, and a nitrogenous base.

Directionality of Nucleic Acid Synthesis

Nucleotides are linked in a $5' \rightarrow 3'$ directional orientation.