Chemical Foundations of Life Vocabulary Flashcards

Vocabulary flashcards covering foundational chemistry concepts, atomic structure, bonding, properties of water, organic carbon chemistry, and the four major biological macromolecules from Chapters 2.1 through 2.5.

Element

A pure substance that cannot be broken down further by chemical methods and contains only one type of atom.

Atom

The basic unit of matter, consisting of a dense central nucleus made of protons and neutrons, surrounded by electrons.

Proton

A positively charged particle with a mass of 1 located in the atomic nucleus that specifies the atomic number of an element.

Neutron

An electrically neutral particle with a mass of 1 located within the atomic nucleus.

Electron

A negatively charged particle with negligible mass that moves around the atomic nucleus within defined regions called orbitals.

Atomic Number

The specific number of protons contained in an atom's nucleus, which defines the chemical identity of an element.

Atomic Mass

The mass of an atom, determined by the combined total number of its protons and neutrons.

Isotopes

Atoms of the same element that share the same number of protons but differ in their number of neutrons.

Ion

An electrically charged atom created when an atom gains or loses one or more electrons.

Orbital

A specific region of space around an atomic nucleus where an electron is present most of the time.

Shell

An energy level surrounding an atomic nucleus composed of one or more orbitals occupied by electrons.

Molecule

A group of two or more atoms attached together by chemical bonds that acts as a single unit.

Chemical Bond

A form of attraction between atoms that holds them together to form molecules.

Valence Electrons

The electrons located in the outermost orbital shell of an atom at its highest energy level.

Covalent Bond

A chemical bond formed when two atoms share a pair of valence electrons in a merged molecular orbital.

Double Bond

A covalent bond formed when two adjacent atoms share two pairs of electrons across two molecular orbitals.

Octet Rule

The tendency of many elements to combine in ways that complete eight electrons in their outermost shell for optimal stability.

Polar Covalent Bond

A covalent bond in which electrons are shared unequally between atoms due to a difference in electronegativity.

Electronegativity

The intrinsic ability of an atom to attract shared bonding electrons toward its nucleus.

Nonpolar Covalent Bond

A covalent bond between atoms that have identical or nearly identical electronegativities, sharing electrons almost equally.

Ionic Bond

A chemical attraction between oppositely charged ions formed when one atom completely transfers an electron to another.

Chemical Reaction

A process that breaks and forms chemical bonds to transform starting substances (reactants) into ending substances (products).

Polar Molecule

A molecule featuring polar covalent bonds that result in distinct regions of slight positive and slight negative charge.

Hydrophilic

A property of polar compounds ("water loving") that allows them to readily dissolve in aqueous solutions.

Hydrophobic

A property of nonpolar compounds ("water fearing") that causes them to minimize contact with water.

Hydrogen Bond

An interaction between a hydrogen atom carrying a slight positive charge and an electronegative atom of another molecule.

Cohesion

The property of like molecules, such as water, tending to stick to one another via intermolecular interactions.

pH

A logarithmic measurement of proton concentration in a solution, calculated using the formula $pH = -\log([H^+])$.

Acid

A molecule that releases a proton ($H^+$) in an aqueous solution, causing the pH to drop below 7.

Base

A molecule that accepts a proton ($H^+$) in an aqueous solution, causing the pH to rise above 7.

Organic Molecule

A carbon-containing molecule that forms the chemical framework for living organisms.

Isomers

Molecules that share the exact same chemical formula (such as isoleucine and leucine, $C_6H_{13}O_2N$) but have different structural arrangements.

Polymer

A complex macromolecule constructed from repeated simpler units (monomers or subunits) connected by covalent bonds.

Functional Group

A specific group of one or more atoms attached to a carbon backbone that exhibits particular chemical properties independently.

Enzyme

A specialized protein that functions as a catalyst to accelerate the rate of cellular chemical reactions.

Amino Acid

The monomer building block of proteins, consisting of a central alpha carbon bound to an amino group, carboxyl group, hydrogen atom, and variable R group.

Peptide Bond

The covalent bond linking the carboxyl carbon of one amino acid to the amino nitrogen of another via a dehydration reaction.

Nucleic Acid

An informational macromolecule, such as DNA or RNA, composed of nucleotide chains that store and transmit genetic information.

Nucleotide

The basic structural unit of nucleic acids, consisting of a 5-carbon sugar, a nitrogen-containing base, and one or more phosphate groups.

Pyrimidine

A category of nitrogenous bases characterized by a single-ring structure, including cytosine (C), thymine (T), and uracil (U).

Purine

A category of nitrogenous bases characterized by a double-ring structure, including guanine (G) and adenine (A).

Phosphodiester Bond

The covalent linkage that connects the phosphate group of one nucleotide to the sugar unit of an adjacent nucleotide.

Carbohydrate

A class of biological molecules made of C, H, and O atoms (typically in a 1:2:1 ratio) that serves as an energy source and structural support.

Monosaccharide

The simplest carbohydrate unit, existing as an unbranched linear or cyclic carbon chain with an aldehyde or ketone group.

Glycosidic Bond

The covalent bond that links monosaccharide units together to build disaccharides and polysaccharides.

Triacylglycerol

An energy-storage lipid composed of three fatty acid chains covalently linked to a 3-carbon glycerol backbone.

Saturated Fatty Acid

A fatty acid chain that contains no carbon-carbon double bonds, maximizing the number of hydrogen atoms bound to each carbon.

Unsaturated Fatty Acid

A fatty acid chain that contains one or more carbon-carbon double bonds, introducing physical kinks into the hydrocarbon chain.

Van der Waals Forces

Weak intermolecular attractions created by transient asymmetries in electron distributions between neighboring nonpolar molecules.

Steroid

A hydrophobic lipid molecule characterized by a core structure of four fused carbon rings, such as cholesterol.