EXAM 1 STUDY GUIDE: Campbell Biology Chapters 1-5: The Chemical Context of Life Flashcards

Vocabulary flashcards covering core chemical terms, concepts, subatomic particles, atomic structures, chemical bonding, and reactions from Chapter 2 of Campbell Biology.

Matter

Anything that takes up space and has mass.

Element

A substance that cannot be broken down to other substances by chemical reactions.

Compound

A substance consisting of two or more elements in a fixed ratio, possessing characteristics different from those of its constituent elements.

Emergent Properties

Properties of a compound that are distinct from those of its individual elements due to specific organization and bonding.

Essential Elements

Elements required for an organism to live and reproduce, comprising about $20\text{–}25$% of the $92$ natural elements.

Trace Elements

Elements required by an organism in only minute quantities, comprising less than $0.01$% of mass.

Atom

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

Neutron

A subatomic particle having no electrical charge, located in the atomic nucleus with a mass close to $1\text{ dalton}$.

Proton

A subatomic particle with a positive electrical charge ($+$), located in the atomic nucleus with a mass close to $1\text{ dalton}$.

Electron

A subatomic particle with a negative electrical charge ($-$), moving in a cloud around the nucleus of an atom.

Dalton

The unit of measurement used to express the mass of subatomic particles such as protons and neutrons.

Atomic Number

The number of protons in the nucleus of an atom, unique to a particular element.

Mass Number

The total sum of protons plus neutrons in the nucleus of an atom.

Atomic Mass

The total mass of an atom, which can be closely approximated by its mass number.

Isotopes

Two or more atoms of the same element that have the same number of protons but differ in the number of neutrons.

Radioactive Isotope

An isotope in which the nucleus decays spontaneously, giving off particles and energy.

Half-Life

The fixed amount of time required for a parent isotope to decay into its daughter isotope.

Radiometric Dating

A method for determining the age of fossils or rocks by measuring the ratio of different isotopes and calculating how many half-lives have elapsed.

Energy

The capacity to cause change.

Potential Energy

The energy that matter possesses because of its location or structure.

Electron Shells

States or energy levels of varying distances from the nucleus where electrons are distributed.

Valence Electrons

Electrons located in the outermost electron shell of an atom, determining its chemical behavior.

Valence Shell

The outermost electron shell of an atom containing valence electrons.

Chemically Inert

The state of an element having a full valence shell, rendering it unreactive with other elements.

Orbital

The three-dimensional space where an electron is found $90$% of the time.

Chemical Bond

An attraction that holds atoms close together through the sharing or transferring of valence electrons.

Covalent Bond

A strong chemical bond formed when two atoms share a pair of valence electrons.

Molecule

Two or more atoms held together by covalent bonds.

Single Bond

A covalent bond representing the sharing of one pair of valence electrons ($H-H$).

Double Bond

A covalent bond representing the sharing of two pairs of valence electrons ($O=O$).

Structural Formula

A chemical notation representing atoms and covalent bonds within a molecule.

Molecular Formula

An abbreviated formula indicating the type and quantity of atoms in a molecule (such as $H_2$ or $H_2O$).

Valence

An atom's bonding capacity, usually equal to the number of unpaired electrons required to complete its outer shell.

Electronegativity

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

Nonpolar Covalent Bond

A covalent bond in which electrons are shared equally between two atoms of similar electronegativity.

Polar Covalent Bond

A covalent bond between atoms that differ in electronegativity, leading to unequal sharing of electrons and partial electric charges.

Ion

An atom or molecule that has gained or lost valence electrons, thereby acquiring a net electrical charge.

Cation

A positively charged ion.

Anion

A negatively charged ion.

Ionic Bond

A chemical bond resulting from the electrostatic attraction between oppositely charged cations and anions.

Ionic Compounds

Compounds formed by ionic bonds, also known as salts, which typically form crystals in nature.

Hydrogen Bond

A weak bond formed when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom.

Van der Waals Interactions

Weak, transient attractions between adjacent molecules resulting from temporary non-uniform electron distribution.

Chemical Reactions

Processes that make and break chemical bonds, leading to changes in the composition of matter.

Reactants

The starting molecules of a chemical reaction.

Products

The resulting molecules formed by a chemical reaction.

Photosynthesis

A chemical process powered by sunlight that converts carbon dioxide and water into glucose and oxygen ($6\,CO_2 + 6\,H_2O \rightarrow C_6H_{12}O_6 + 6\,O_2$).

Chemical Equilibrium

The point at which forward and reverse chemical reactions occur at identical rates, leaving reactant and product concentrations unchanged.