Wk 1 – Atoms, Molecules, and Life

Matter

Anything that has mass and takes up a volume of space.

Element

A pure substance of matter with distinct physical and chemical properties.

Atom

The smallest unit of an element that retains the element's properties.

Nucleus

The dense core of an atom containing protons and neutrons.

Proton

A positively charged subatomic particle with a mass of 1 AMU.

Neutron

A neutrally charged subatomic particle with a mass of 1 AMU.

Electron

A negatively charged subatomic particle orbiting the nucleus with negligible mass.

Ion

An atom that has an electrical charge, either positive or negative.

Atomic Number

The number of protons in an atom's nucleus.

Atomic Mass Number

The total number of protons and neutrons contained in the nucleus.

Isotope

Atoms of an element with the same number of protons but different neutrons.

Molecule

Atoms linked together.

Chemical Reaction

The process of linking atoms or molecules together or tearing them apart.

Chemical Bond

Attractive forces that hold atoms together.

Ionic Bond

A bond where atoms are held together by opposite electrical charges.

Covalent Bond

A strong bond where two atoms share electrons.

Nonpolar

Having no charge on any part of the molecule.

Polar Bond

A bond with partial positive and negative charges due to unequal electron attraction.

Hydrogen Bond

An electrical attraction that occurs between two polar molecules.

Cohesion

The tendency of water molecules to stick together.

Surface Tension

The tendency of a water surface not to break.

Adhesion

The tendency of water molecules to cling to other substances.

Capillary Action

Water movement in porous materials due to adhesion, cohesion, and surface tension.

Solvent

A substance that surrounds and dissolves another substance.

Solute

Any substance that can be dissolved by a solvent.

Solution

A fluid where a solute is dissolved in a solvent.

Hydrophilic

Molecules attracted to and dissolved in water.

Hydrophobic

Larger nonpolar molecules that do not dissolve in water.

Specific Heat

Energy needed to raise one gram of water 1 degree Celsius.

Heat of Vaporization

Amount of energy needed to cause a substance to evaporate.

Neutral pH

Equal concentrations of H+ and OH- ions, resulting in a pH of 7.

Acid

A solution where the concentration of H+ ions exceeds OH- ions (pH < 7).

Base

A solution where the concentration of OH- ions exceeds H+ ions (pH > 7).

Buffer

A molecule that tends to maintain a solution at nearly constant pH.