Chapter 2: Water and Carbon - Vocabulary Flashcards

Vocabulary practice flashcards covering fundamental chemistry, atomic structure, properties of water, carbon chemistry, isomers, functional groups, and macromolecule assembly.

Element

A substance that cannot be broken down further into other substances by chemical reactions and is composed of only one type of atom.

Compound

A substance consisting of two or more different elements combined in a fixed ratio, exhibiting emergent properties distinct from its constituent elements.

Essential Elements

The approximately 20–25% of the 92 natural elements that an organism requires to live a healthy life and reproduce.

Trace Elements

Elements required by an organism in only minute quantities, making up less than $0.01\text{\%}$ of total body mass.

Atom

The smallest unit of matter that still retains the unique chemical properties of an element.

Neutron

A subatomic particle located in the atomic nucleus that carries no electrical charge.

Proton

A subatomic particle located in the atomic nucleus that carries a single positive electrical charge.

Electron

A subatomic particle carrying a single negative electrical charge that moves rapidly around the atomic nucleus in a cloud.

Dalton (Da)

A standard unit used to measure mass of subatomic particles, where $1\,\text{Da} = 1.7 \times 10^{-24}\,g$.

Atomic Number

The number of protons in the nucleus of an atom, which is unique and characteristic to each element.

Mass Number

The total sum of protons plus neutrons contained within the nucleus of a single atom.

Atomic Mass

The average mass of all naturally occurring elemental forms, taking into consideration isotopes and their relative abundances.

Isotopes

Different atomic forms of the same element that possess identical numbers of protons but varying numbers of neutrons.

Radioactive Isotopes

Atoms with unstable nuclei that shed particles and lose energy via radioactive decay to obtain nuclear stability.

Orbital

A three-dimensional volume of space around an atomic nucleus where an electron is found approximately $90\text{\%}$ of the time.

Valence Electrons

Electrons located in the outermost shell (valence shell) of an atom that determine its chemical behavior and bonding capacity.

Octet Rule

The observation that elements tend to react and bond in such a way that each atom achieves eight electrons in its valence shell to become chemically stable.

Covalent Bond

The strongest type of chemical bond in a cell, formed by the sharing of a pair of valence electrons by two atoms.

Single Bond

A covalent bond formed by the sharing of one pair of valence electrons between two atoms.

Double Bond

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

Electronegativity

The measure of an atom's attraction for shared electrons within a covalent bond.

Nonpolar Covalent Bond

A covalent bond in which shared electrons are pulled equally between two atoms with similar electronegativities (difference $\le 0.4$).

Polar Covalent Bond

A covalent bond between atoms with significantly different electronegativities (difference $> 0.4$), leading to unequal electron sharing and partial charges.

Ionic Bond

A chemical bond resulting from the electrostatic attraction between oppositely charged ions formed when one atom completely transfers an electron to another.

Cation

A positively charged ion produced when an atom loses one or more valence electrons.

Anion

A negatively charged ion produced when an atom gains one or more valence electrons.

Hydrogen Bond

A weak chemical attraction that forms when a hydrogen atom covalently bonded to an electronegative atom is attracted to a nearby electronegative atom.

Cohesion

The attraction between molecules or atoms of the same substance, such as hydrogen bonding holding water molecules together.

Adhesion

The attraction between two different substances, such as water molecules adhering to solid cell walls.

Surface Tension

A measure of how difficult it is to stretch or break the surface of a liquid, governed by cohesive forces.

Specific Heat

The quantity of heat that must be absorbed or lost for $1\,g$ of a substance to change its temperature by $1^\circ\text{C}$.

Heat of Vaporization

The quantity of energy required to convert $1\,g$ of a liquid substance into a gas.

Solution

A liquid mixture that is completely homogeneous throughout, consisting of two or more substances.

Solvent

The dissolving agent in a solution, present in the greatest quantity.

Solute

The substance that is dissolved by a solvent in a solution.

Aqueous Solution

A solution in which water acts as the solvent.

Hydration Shell

A sphere of oriented water molecules surrounding each dissolved ion when an ionic compound dissolves in water.

Hydrophilic

Referring to polar or charged molecules that have an affinity for water and easily interact with or dissolve in it.

Hydrophobic

Referring to nonpolar and uncharged molecules that do not dissolve in water and instead group together via hydrophobic interactions.

Acid

A substance that increases the hydrogen ion ($H^+$) or hydronium ion ($H_3O^+$) concentration of a solution, yielding a pH value less than 7.

Base

A substance that decreases the hydrogen ion ($H^+$) concentration of a solution, yielding a pH value greater than 7.

Buffer

A substance—typically a weak acid and its corresponding base—that minimizes drastic changes in $H^+$ and $OH^-$ concentrations to maintain pH homeostasis.

Tetravalence

The property of carbon having four valence electrons, allowing it to form four covalent bonds with surrounding atoms.

Isomers

Compounds that possess identical molecular formulas but differ in their structural arrangements and chemical properties.

Structural Isomers

Isomers that share the same molecular formula but differ in the covalent arrangement of their carbon skeletons or atoms.

Cis-Trans Isomers

Geometric isomers that have the same covalent bonds but differ in the spatial arrangement of functional groups around a double bond.

Enantiomers

Isomers that are non-superimposable mirror images of each other due to the presence of an asymmetric carbon atom.

Functional Groups

Specific chemical groups attached to organic carbon skeletons that participate directly in chemical reactions and define a molecule's unique chemical properties.

Polymer

A long, complex molecule composed of many similar or identical covalent building blocks joined together.

Monomer

A small repeating chemical subunit that serves as the building block of a polymer.

Dehydration Reaction

A condensation reaction that covalent links monomers together into a growing polymer through the removal of a water molecule.

Hydrolysis

A chemical reaction that breaks covalent bonds in polymers by adding a water molecule, disassembling them into individual monomers.