the chemical foundation of life

Atom

Smallest unit of matter that retains all of the element's chemical properties.

Nucleus

Center of the atom that contains protons and neutrons.

Proton

Positively charged particle in the nucleus of an atom.

Neutron

Uncharged particle in the nucleus of an atom.

Electron

Negatively charged particle that orbits the nucleus.

Atomic Number

Number of protons in an atom.

Mass Number

Total number of protons and neutrons in an atom.

Atomic Mass

Calculated mean of the mass number for naturally occurring isotopes.

Isotopes

Different forms of an element with the same number of protons but different numbers of neutrons.

Radioisotopes

Isotopes that emit particles and attain a more stable atomic configuration.

Periodic Table

Organizes and displays different elements.

Chemical Reactivity

Ability of elements to combine and chemically bond with each other.

Molecules

Two or more atoms chemically bonded together.

Orbitals

Regions where electrons are located in the atom.

Octet Rule

Principle stating that 8 electrons are needed in the valence shell for stability.

Valence Shell

Outermost electron shell of an atom.

Inert/Noble Gases

Atoms with fully filled outer electron shells.

Cations

Positive ions formed by the loss of electrons.

Anion

Negatively charged ions formed by the gain of electrons.

Electron Transfer

Movement of electrons from one element to another.

Ionic Bonds

Bonds formed between ions with opposite charges.

Covalent Bonds

Bonds formed by sharing electrons between atoms.

Polar Covalent Bonds

Bonds where electrons are unequally shared, favoring the positively charged nucleus.

Electronegativity

Measure of the attraction of an atom for electrons.

Non-Polar Covalent Bonds

Bonds formed between atoms that share electrons equally.

Hydrogen Bonds

Weak bonds that form between water molecules.

Van der Waals Interactions

Weak attractions or interactions between molecules.

Water Polarity

Water is composed of polar molecules with hydrogen bonds between hydrogen and oxygen.

Hydrophilic

Substances that are water-loving.

Hydrophobic

Substances that are water-hating.

Water States

Water can exist in liquid, gas, and solid states.

Low Density

Ice is less dense than liquid water.

Water High Heat Capacity

Water has the highest specific heat capacity of any liquid.

Specific Heat Capacity

Amount of heat required to change the temperature of one gram of a substance by 1 degree Celsius.

Heat of Vaporization

Amount of energy required to change one gram of a liquid to a gas.

Evaporation

Process of changing from liquid to gas.

Solvent

Substance capable of dissolving other polar molecules and ionic compounds.

Sphere of Hydration

Formation of a shell of water molecules around ions.

Dissociation

Process where atoms or groups of atoms break off from molecules and form ions.

Cohesion

Attraction between water molecules that allows for surface tension.

Surface Tension

Capacity of a substance to withstand rupture when placed under tension or stress.

Adhesion

Attraction between water molecules and other molecules.

Capillary Action

Movement of water through a narrow space due to cohesive and adhesive forces.