Unit 1: Composition of Ocean Water, Solubility, Salinity, pH, and Ocean Layers (VOCABULARY flashcards)

Vocabulary flashcards covering composition of seawater, solubility, salinity, pH, and ocean layering concepts from the notes.

Chloride (Cl-)

Major anion in seawater; makes up about 55% of dissolved ions.

Sodium (Na+)

Major cation in seawater; makes up about 30% of dissolved ions.

Magnesium (Mg2+)

Dissolved cation in seawater; contributes ~3.7% of dissolved ions.

Sulfate (SO4^2-)

Major anion in seawater; accounts for about 7–8% of dissolved ions.

Calcium (Ca2+)

Dissolved cation in seawater; around ~1% of dissolved ions.

Potassium (K+)

Dissolved cation in seawater; about ~1% of dissolved ions.

Sea water composition

A solution containing a mixture of dissolved salts and compounds.

Water molecule

H2O; covalent bonds between H and O; bent shape.

Atom

Smallest unit of an element with a nucleus (protons + neutrons) and electrons.

Nucleus

Center of an atom that contains protons and neutrons.

Electron shells

Energy-level regions around the nucleus where electrons reside.

Covalent bond

Bond formed by sharing electron pairs between atoms (as in H–O in water).

Ionic bond

Bond formed by transfer of electrons creating charged ions (e.g., Na+ and Cl-).

Hydrogen bond

Weak attraction between a hydrogen atom and a electronegative atom; important in water properties.

Solvent

Substance dissolving solutes (water in seawater).

Solute

Substance dissolved in a solvent (e.g., salt).

Solubility

Ability of a solute to dissolve in a solvent under given conditions.

Dissolution

Process of a solute dissolving in a solvent.

Salinity

Concentration of dissolved salts in seawater; measured in ppt.

Solubility of salts in water

Ionic bonds in salt break and ions become solvated by water molecules; salts dissolve.

Density

Mass per unit volume; affected by temperature, pressure and salinity; drives ocean layering.

Photic zone

Sunlit surface layer from 0 to ~200 m; also called epipelagic.

Epipelagic

Surface ocean layer (0–200 m) with abundant light.

Mesopelagic

Twilight zone (~200–1000 m); limited light.

Bathypelagic

Dark deep-ocean zone (~1000–4000 m).

Abyssal

Very deep ocean zone (approximately 4000–6000 m).

Hadalpelagic

Deepest ocean zone (>6000 m, in trenches).

Benthic

Bottom zone; the seafloor.

Pelagic

Open-water column away from the bottom.

Neritic

Nearshore waters over the continental shelf.

Continental shelf

Shallow region extending from coast to shelf break.

Oceanic

Open ocean beyond the continental shelf.

Thermocline

Depth layer where temperature changes rapidly with depth.

Halocline

Layer with a rapid change in salinity with depth.

Density gradient

Vertical change in density due to temperature and salinity differences.

Hypersaline

Salinity greater than about 40 ppt; very salty (brine).

Brine

Very salty water; often used to describe hypersaline conditions.

CO2 in seawater forms carbonic acid

Dissolved CO2 reacts with water to form H2CO3, contributing to ocean acidification.

Gases exchange with atmosphere

Gases like CO2 and O2 are exchanged between air and surface water due to turbulence and waves.

CO2 solubility vs temperature

Gases, including CO2, dissolve better in cold water than in warm water.

Oxygen solubility in water

O2 is less soluble than CO2 and can decrease with warming.

pH

Measure of hydrogen ion concentration; 0–14 scale; below 7 acidic, 7 neutral, above 7 alkaline.

Litmus indicator

Qualitative pH test that changes color to indicate acidic vs alkaline.

Universal indicator

pH indicator showing a range of pH values by color.

pH probe

Electronic device that measures pH by detecting H+ concentration; highly precise and requires calibration.

Historical ocean pH

Historically around 8.2; recent CO2 increases have edged it toward ~8.1, indicating higher acidity.