Chapter 3: Water and Its Properties

This set of vocabulary flashcards covers the chemical structure, types of bonds, and unique physical properties of water as presented in Chapter 3.

Water Content in Cells

Most cells are surrounded by water, and the cells themselves are composed of approximately $70 \text{--} 95\%$ water.

Water Molecule Composition

A molecule made up of two hydrogen atoms and one oxygen atom with the molecular formula $H_2O$.

Oxygen Valence Shell

A single oxygen atom contains six electrons in its outermost shell, which can hold a total of eight electrons.

Electronegativity

An atom's attraction for the electrons in a covalent bond; the more electronegative an atom, the more strongly it pulls shared electrons toward itself.

Polar Molecule

A molecule, such as water, where one end is partially positive ($H$) and the other is partially negative ($O$) due to unequal sharing of electrons.

Covalent Bond

An intramolecular force that holds atoms together within a molecule by the sharing of electrons; it is stronger than a hydrogen bond.

Non-polar Covalent Bond

A type of covalent bond where atoms have similar electronegativity and share the electrons equally, resulting in no charges on the atoms.

Polar Covalent Bond

A type of covalent bond where one atom is more electronegative than the other, resulting in unequal sharing of electrons and partial charges.

Hydrogen Bond

An intermolecular force where a hydrogen atom bonds to a highly electronegative atom (such as fluorine, oxygen, or nitrogen) of another molecule.

Hydrophilic

Substances that are "water-loving" and dissolve readily in water; they are typically composed of ions or polar molecules like sodium chloride ($NaCl$).

Hydrophobic

Substances that are "water-fearing" and are insoluble in water; they are usually non-polar molecules like hydrocarbons or vitamins $A$, $D$, $E$, and $K$.

Cohesion

A property in which the same molecules stick together, such as water molecules sticking to each other due to hydrogen bonding.

Adhesion

A property in which different molecules stick together, such as water molecules sticking to plant cell walls.

Capillary Action

The process plants use to pull water from the ground up through the roots to their leaves.

Transpiration

The loss of water from plants through the process of evaporation.

Surface Tension

An effect within the surface layer of a liquid that causes it to behave as an elastic sheet, allowing insects like water striders to walk on water.

Specific Heat

The amount of heat that must be absorbed or lost by $1\,g$ of a substance to change its temperature by $1\,^{\circ}C$.

High Specific Heat Capacity

A property of water that allows it to heat up slowly and hold its temperature longer, helping organisms maintain constant internal temperatures and stabilizing ocean environments.