Chemical Basis of Life

Vocabulary flashcards covering key atomic, chemical bonding, water property, and pH concepts from the Chemical Basis of Life lecture notes.

Atom

The basic unit of matter, consisting of two main regions: the nucleus and the electron cloud.

Nucleus (Atomic)

The center of an atom that is formed from protons and neutrons.

Electron Cloud

The region outside of the nucleus containing energy levels or orbits where electrons are located.

Protons ($p^+$)

Positively charged subatomic particles located in the nucleus with a mass of $1\,\text{amu}$ (atomic mass unit).

Neutrons ($n^0$)

Subatomic particles with a neutral charge located in the nucleus with a mass of $1\,\text{amu}$.

Electrons ($e^-$)

Negatively charged subatomic particles that are the only particles found in the electron cloud.

Energy Level Capacity Formula

The formula $2n^2$, where $n$ is the variable for the energy level number, used to determine electron capacity.

Outermost Energy Level

The outermost electron shell of an atom, which can hold a maximum of $8$ electrons and determines the chemical properties of the atom.

Element

A pure substance made up of one kind of atom that cannot be broken down into other substances by physical or chemical means.

Periodic Table

A tabular arrangement of chemical elements organized by increasing atomic number.

Isotopes

Atoms of the same element that have a different number of neutrons, giving them different atomic masses.

Radioactive Isotope

An isotope whose nucleus is unstable and breaks down over time.

Mass Number

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

Compound

A substance formed when atoms of two or more elements combine in specific fixed ratios, represented by a chemical formula such as $\text{H}_2\text{O}$.

Valence Electrons

The outer electrons available for atoms to share or transfer in order to form chemical bonds.

Chemical Bond

An attraction between atoms created when outer electrons are attracted, shared, or transferred so atoms become chemically stable.

Ionic Bond

A chemical bond formed when one or more electrons are transferred from one atom to another, forming oppositely charged ions whose attraction holds the compound together.

Covalent Bond

A chemical bond formed when two nonmetal atoms share electrons (sharing $2$, $4$, or $6$ electrons).

Polarity

A condition that occurs when there is an unequal sharing of electrons across a bonded molecule.

Hydrogen Bond

A bond formed between the hydrogen atom of one water molecule and the oxygen atom of a different water molecule.

Cohesion

The force of attraction between molecules of the same substance.

Adhesion

The force of attraction between molecules of different substances.

Surface Tension

A property of water caused by cohesion that allows water molecules to attract one another strongly at the surface.

Capillary Action

The ability of water to move upward through small tubes due to the combined effects of cohesion and adhesion.

High Heat of Vaporization

A property of water requiring a high amount of thermal energy for liquid water to evaporate into a gas.

pH Scale

A measurement system ranging from $0$ to $14$ used to measure the concentration of $\text{H}^+$ ions in a solution, with $7$ being neutral.

Acid

A compound that releases $\text{H}^+$ ions in solution, resulting in a pH below $7$.

Base

A compound that releases $\text{OH}^-$ ions in solution, resulting in fewer $\text{H}^+$ ions and a pH above $7$.

Buffer

A weak acid or base that reacts with strong acids or bases to prevent sudden, drastic changes in pH.