Unit 1: Chemistry of Life - Properties of Water, Elements, and Macromolecules Vocabulary

Vocabulary flashcards covering the properties of water, elements of life, functional groups, and basic biological macromolecules.

Polarity

Unequal sharing of electrons between the oxygen and hydrogen atoms in water, giving the molecule a partially negative end (O) and partially positive end (H).

Hydrogen bond

A weak attraction between the partially positive H of one water molecule and the partially negative O of a nearby water molecule (or other polar molecule).

Cohesion

Water molecules sticking to each other via hydrogen bonds.

Adhesion

Water molecules sticking to other (non-water) polar surfaces or molecules.

Surface tension

The result of cohesion at the water's surface; lets small, dense objects rest or move on top of water.

Capillary action

Movement of water through narrow spaces (like plant xylem) due to a combination of cohesion and adhesion.

Specific heat

The amount of heat needed to change water's temperature; water's specific heat is high, so it resists rapid temperature change.

Heat of vaporization

The amount of heat energy required to evaporate water; water's is high, which is why evaporative cooling (e.g., sweating) is effective.

Density of ice vs. liquid water

Ice is less dense than liquid water because hydrogen bonds hold water molecules in a more open crystalline lattice when frozen, so ice floats.

Solvent properties / "universal solvent"

Water's polarity allows it to dissolve other polar or ionic (charged) substances by surrounding and separating their particles.

Acid, base, pH

Acids increase $H^+$ ion concentration (lower pH); bases decrease it (raise pH); pH scale runs $0-14$.

Buffer / buffering capacity

A system (like blood) that resists large swings in pH when acid or base is added.

Element

A pure substance made of only one type of atom (e.g., carbon, hydrogen, oxygen, nitrogen).

Macromolecule / organic molecule

A large molecule built mainly from carbon, often containing functional groups that determine its chemical behavior.

Functional group

A specific group of atoms within a molecule that gives that molecule characteristic chemical properties.

Hydroxyl group ($-OH$)

Polar group; found in alcohols and sugars; involved in dehydration/hydrolysis reactions.

Carboxyl group ($-COOH$)

Acidic group; found in amino acids and fatty acids; can donate an $H^+$ ion.

Amino group ($-NH_2$)

Basic group; found in amino acids; can accept an $H^+$ ion.

Carbonyl group ($-C=O$)

Found in sugars and other molecules; can be positioned as an aldehyde or ketone.

Methyl group ($-CH_3$)

Nonpolar group; affects the shape and behavior of a molecule (e.g., in DNA methylation).

Phosphate group ($-PO_4$)

Found in nucleic acids and ATP; involved in energy transfer.

Monomer

A single small subunit that can bond with other monomers to build a larger molecule.

Polymer

A large molecule made of many repeating monomers joined together by covalent bonds.

Monosaccharide

A single sugar unit (monomer of carbohydrates), e.g., glucose.

Dehydration synthesis (condensation reaction)

A reaction that builds a polymer by joining two monomers together and releasing a water molecule.

Hydrolysis

A reaction that breaks a polymer apart into monomers by adding a water molecule.

Glycosidic bond

The covalent bond that links two monosaccharides together (formed during dehydration synthesis, broken during hydrolysis).

Covalent bond

A bond formed when atoms share electrons; the type of bond that links monomers within a polymer.