Properties of Water

• Earth is called the blue planet due to its water coverage, making water vital for the planet.
• Water molecules consist of two hydrogen atoms and one oxygen atom.
• Water is essential for human endeavors and biological processes.
• Water facilitates transport, excretion, and chemical reactions in humans and animals.
• Water creates tension in small plants, enabling them to stand upright and reach sunlight.
• Water is used for cooking, cleaning, crop growing, manufacturing, and electricity generation.
• Fresh water shortages occur despite the abundance of salt water due to high human consumption.
• The water cycle evaporates seawater and precipitates fresh water.

Molecular Structure and Properties of water

• Molecules are made of atoms bonded together through ionic or covalent bonds.
• Water is a molecule comprised of an oxygen atom bonded to two hydrogen atoms through polar covalent bonds.
• Water molecules have a bent shape due to the angles at which hydrogen atoms bond with oxygen atoms, which is due to the space needed for unbonded electrons.
• Polar molecules have partial or full charges, known as dipoles, due to uneven electron distribution in polar covalent bonds.
• Oxygen is more electronegative than hydrogen in water, resulting in a negative dipole on oxygen and positive dipoles on hydrogen atoms.
• Dipoles on water molecules allow for hydrogen bonding, which gives water many unique properties including cohesion and adhesion.
• Hydrogen bonding results from the interaction between the strong dipoles on hydrogen and oxygen atoms of different water molecules.
• Only other polar molecules can dissolve in water due to water's polarity.
• Water's bent molecular structure, with slightly negative charge on one side and positive charge near the hydrogen atoms, enables hydrogen bonds.
• Hydrogen bonds are weak electrostatic attractions between the negatively-charged oxygen atom of one water molecule to the electron-deficient hydrogen atom of another.

Water's Properties

• The crystalline structure of ice makes it less dense than water, this is because Hydrogen bonds expand slightly as water freezes.
• Water has a high specific heat capacity (1 cal/g°C), making it harder to change its temperature.
• Water exhibits cohesive and adhesive properties, contributing to capillary action, which is the ability of water to move against gravity in a narrow space.
• Water has a high heat of vaporization, requiring significant energy for liquid water to turn into gas.
• Water has high surface tension, resisting stretching or breaking due to hydrogen bonds.
• These properties make water essential for Earth's habitability, regulating temperature and supporting plant and animal life.

The Water Cycle

• The water cycle recycles freshwater and moves it on, above, and below the Earth's surface.
• The main parts of the water cycle are evaporation, condensation, and precipitation.
• Water changes phases from liquid to solid to gas, and back again in the water cycle.
• Evaporation, sublimation, and transpiration are the processes where water changes from liquid to gas, re-entering the atmosphere.
• Condensation is the process where water changes from gas to liquid, leading to precipitation.
• Precipitation returns water to the surface as rain, snow, sleet, or hail.
• Runoff, driven by gravity, carries water across the ground.
• Water returns to the groundwater supply through infiltration.
• Water travels from the surface to the atmosphere and back through the water cycle.
• Evaporation from surface water and transpiration through plants is known as evapotranspiration.
• Evaporation rates increase in sunny, dry, windy, or warm conditions.
• Water condenses into clouds in the atmosphere.

Phase Changes

• Phase change occurs when energy and pressure are added or removed from a system.
• The phases most often found in nature are solid, liquid, and gas/vapor.
• Evaporation is the process of changing from a liquid to a vapor, also called boiling, and happens at the boiling point of a liquid.
• Condensation occurs when a gas/vapor loses energy or gains pressure to move to a liquid state.
• Sublimation happens when a gas is formed from a solid, skipping the liquid state.
• Deposition is the opposite process of sublimation and is when gas goes to a solid, skipping the liquid phase.
• Freezing is a process where a liquid loses energy or gains enough pressure that it turns into a solid.
• Melting occurs when a solid gains energy or loses pressure to become fluid or liquid.
• A supercritical fluid is formed when the pressure and energy of a system are so high.
• The critical point is when the boundary between a liquid and a vapor is gone, and the vapor and liquid are indistinguishable.
• The triple point is when a system reaches a certain temperature and pressure, and all three phases can coexist together.

Runoff and Infiltration

• Runoff and infiltration are two routes water can take in the water cycle after precipitation.
• Runoff is water that moves across the surface of the land, while infiltration is water that seeps into the soil.
• Runoff moves large amounts of water around the surface of the Earth and eventually ends in lakes and oceans.
• Runoff occurs when water encounters non-porous surfaces or ground which is already saturated with water.
• Runoff can cause land erosion by stripping away the soil, rocks and nutrients then depositing them in a different place downstream.
• Runoff occurs after a rain or melting event such as a monsoon or melting of ice and snow.
• Infiltration is the moving of surface water into the soil, filling the air space between particles of soil.
• The rate of infiltration is how fast the water can seep into the ground.
• The rate of infiltration will increase in more permeable soil with little or no slope and with vegetation.
• Granite is impermeable so it has no infiltration.
• Limestone holds and allows water to flow through.
• Sand is very porous and permeable with lots of air space around the grains of sand.
• Clay holds water but does not let it flow.
• The water cycle involves water moving between streams, rivers, lakes, underground seepage, seas, water vapor, and clouds.
• Water evaporates, forms clouds, and returns to Earth as rain or snow.
• Transpiration is the evaporation of water from plant leaves.
• The matter is transferred around the water cycle, since water is itself matter.
• Energy from the sun drives the water cycle, causing evaporation.
• Energy transfers between kinetic and potential energy of the molecules throughout the cycle.

Shaping Landforms

• The constant cycling and movement of water on Earth plays a major role in how Earth's surface is shaped.
• Many of Earth's landforms are created by moving water, both above and below the land's surface.
• The speed and composition of the water determines which types of landforms will be created.
• Landforms created by water may occur naturally or may be influenced by human actions.
• Water for rivers and streams starts at the source.
• Along the way, rivers and streams can erode the Earth's surface, carry sediment, and create new features and landforms.

Watersheds

• A watershed is a land area that funnels water to the same place, such as a wetland, river, lake, or ocean.
• Watersheds are defined by drainage divides, which are drawn along the highest ridgeline.
• Watersheds that feed larger water bodies are known as drainage basins.
• Larger basins may have many smaller sub-basins and micro-watersheds nested within them.
• What happens in watersheds affects downstream water quality and streamflow.
• Diffuse contaminants become concentrated as water is funneled to the same place.
• Integrated watershed management can improve water quality, control flooding and erosion, and enhance other free services.

Groundwater

• Groundwater is water that seeps into the Earth's crust through natural crevices and fissures in rock and sediment.
• Groundwater is always moving and never static.
• Three main factors are needed in order for water to flow underground: porosity, permeability, and gravity.
• Porosity is the amount of water the soil can take in and hold.
• Permeability describes how quickly water may pass through the earth.
• Clay has high porosity and less permeability.
• Gravity determines the direction and the rate of flow of water as gravity pulls the water downwards from a high to a low hydraulic gradient.
• Porosity determines how much water the soil can take in, while permeability and gravity determine how fast it can move underground.

Water Conservation

• Water conservation involves strategies to save water and avoid the depletion of water sources.
• Sustainability is a way to manage water usage so current needs are met while maintaining levels for future use.
• Society depends on a clean, abundant water supply for public health, transportation, goods, and food.
• Consumptive water use means water does not go back to the water source.
• Non-consumptive water use means water is returned to its source or not removed from its source.
• Sustainable water use involves reusing or recycling water to avoid waste and prevent depletion.
• Drip irrigation is an example of sustainable water use.
• Consumers can conserve water at home by checking for leaks and using a container when brushing teeth.
• Communities are also taking action to conserve water.
• Portland, Oregon offers rebates for toilet repairs and replacements.
• This saves water, energy, and money that can be allocated for development.

Oceans and Seas

• Bodies of water account for 71% of Earth's surface.
• Oceans and seas hold approximately 96% of all water on Earth.
• Oceans and seas are responsible for climate control and marine biodiversity.
• Approximately 80% of the oceans are unexplored.
• The five oceans are the Arctic, Atlantic, Pacific, Indian, and Southern Oceans.
• The seven seas are the Arctic, North Atlantic, South Atlantic, North Pacific, South Pacific, Indian, and Southern Seas.
• Oceans are large expanses of saltwater between continents.
• Seas are smaller portions of an ocean.
• Gulfs connect landmasses to seas, and seas connect gulfs to oceans.

Ocean Water Properties

• Ocean water has high salinity, which is the amount of salt dissolved in water.
• Ocean water contains sodium chloride, magnesium, sulfate, calcium, and potassium, as well as nitrogen, oxygen, and carbon dioxide.
• Ocean waters range in temperature and have a very high heat capacity.
• The freezing point of ocean water is about 28 degrees Fahrenheit, which is lower than that of freshwater.
• Ocean water density depends mainly on its temperature and salinity.
• Cold, salty water is denser and sinks to the bottom of the ocean below less dense water layers that float on top.

Tectonic Plates and Coastlines

• The Earth's surface is made up of many tectonic plates that are generally defined as continental or oceanic.
• The movement of the plates results in tectonic activity, which shapes the land and sea floor.
• Active continental margins have mountain ranges, oceanic trenches, and volcanic activity.
• Passive margins have low amounts of tectonic activity, flat inland areas, and long rivers and estuaries.
• Emergent coastlines, with steep, rocky cliffs, are the result of tectonic activity around active margins.
• Submergent coastlines, where wide river valleys may be drowned, are commonly found along passive continental margins.

Ocean Basins

• Ocean basins are bowl-shaped depressions filled with salty water and marine life.
• The five ocean basins are the Pacific, Atlantic, Indian, Southern, and Arctic.
• Ocean basins have a continental shelf, slope, and rise.
• The abyssal plain plateau is relatively flat land with sedimentary deposits.
• Plate tectonic activity led to the shape and topography of each ocean basin.
• Seafloor spreading expands the ocean basin while oceanic ridges form, creating a chain of mountains underwater.
• Abyssal hills are less than 3,200 feet tall and form between abyssal plains and mid-ocean ridges.
• Seamounts are inactive volcanoes that reach over 3,200 feet tall and have jagged peaks.
• Guyots are seamounts that once reached above the ocean's surface.
• Subduction creates trenches when two tectonic plates collide.
• Oceanic trenches are deep, V-shaped ditches that extend 18,400 feet or more into the earth's mantle.
• Ocean basins are deemed active if plate tectonic activity still occurs and inactive if it does not.

Oceanic Ridge Systems

• The oceanic ridge system is a continuous mountain chain under the surface of the sea.
• This mountain range is found in all of the major oceans.
• The earth contains an outer crust that covers a deeper layer called the mantle.
• The lithosphere is the outermost shell of the earth and is composed of the crust and the upper part of the mantle.
• Tectonic plates are plate-like sections of the lithosphere.
• Below the lithosphere is the asthenosphere, a zone of semisolid rock that is very hot and deformable.
• Tectonic plates can slide on top of the asthenosphere.
• Tectonic activity, the deformation of the earth's crust, occurs at the boundaries between these plates.
• Magma from the asthenosphere can push up through the gap, causing an underwater volcano.
• The magma cools and solidifies, creating new layers of ocean crust that continues to build, forming the oceanic ridges.

Explore water's unique properties, including its polarity and ability to dissolve substances. Understand the impact of hydrogen bonds on phenomena like surface tension and capillary action. Investigate water's role in temperature regulation and the water cycle.