The Nature of Molecules and the Properties of Water

These flashcards cover key terms and definitions related to molecular structure, chemical bonds, and properties of water.

Chemical Bond

A force of attraction that holds atoms together in a molecule or compound.

Ion

An atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

Covalent Bond

A bond formed when two atoms share electrons.

Acid

A substance that increases the hydrogen ion concentration in a solution, resulting in a lower pH.

Base

A substance that decreases the hydrogen ion concentration in a solution, resulting in a higher pH.

pH Scale

A scale used to specify the acidity or basicity of an aqueous solution, ranging from 0 to 14.

Hydrogen Bond

A weak bond that forms between partially positive hydrogen atoms and partially negative atoms, such as oxygen.

Polar Covalent Bond

A type of covalent bond where electrons are unequally shared between atoms with different electronegativities.

Isotope

Atoms of a single element that have different numbers of neutrons.

Valence Electron

An electron that is found in the outermost shell of an atom and is involved in forming bonds.

Matter

Any substance in the universe that has mass and occupies space.

Atom

Fundamental unit of matter, composed of protons, neutrons, and electrons.

Protons

Positively charged particles located in the nucleus of an atom.

Neutrons

Neutral particles located in the nucleus of an atom.

Electrons

Negatively charged particles that orbit the nucleus in areas called orbitals or valence shells.

Element

Any substance that cannot be broken down into simpler substances by ordinary chemical means.

Isotopes

Atoms of a single element with different numbers of neutrons.

Molecules

Groups of atoms held together in a stable association.

Ionic Bonds

Bonds that form from the loss or gain of electrons, with an electrostatic attraction between oppositely charged ions.

Covalent Bonds

Bonds formed when two elements with similar electronegativity share electrons to complete their valence shells.

Polar Covalent Bonds

Covalent bonds where one atom has higher electronegativity than another, resulting in unequal sharing of electrons (e.g., in water).

pH scale

A scale that measures hydrogen ion concentration in solutions.

Acid

Any substance that increases $[H^+]$ in solution and decreases pH.

Base

Any substance that lowers $[H^+]$ by binding with hydrogen ions, increasing pH.

Buffers

Systems that resist changes in pH by absorbing excess $H^+$ or releasing $H^+$ when base is added.

Cohesion (Water)

The property of water molecules attracting each other, leading to high surface tension.

Adhesion (Water)

The property of water being able to stick to other polar molecules.

High Specific Heat (Water)

The property of water requiring significant energy input to change its temperature.