1. Earth’s Waters
Chapter 15 p. 524

2. 15.1 The Water Planet
Water is necessary for life so scientist are always looking for water on other planets
Climate and weather is influenced by ocean currents
Many animals have water habitats
People use water to transport goods, for recreation and for agriculture

3. Biological Functions-Reason 1
All organisms require/depend on water to live. About 60% of the human body is made up of water. Seeds and plants require water to grow.
Water carries nutrients and carries waste from cells. It is essential for chemical reactions like photosynthesis to produce sugar and oxygen (beginning of food chain).
Water helps regulate body temp through sweating.
We also use water for bathing, cooking, and drinking.

4. Warming Earth-Reason 2
Earth’s atmosphere traps thermal energy from the sun, Greenhouse Effect.
Some is absorbed and some is reflected. Water vapor is concentrated in the Greenhouse Effect.
Without the Greenhouse Effect, Earth’s waters would be ice and no organisms could survive.

5. Keeping Earth’s Temp Stable-Reason 3
Water has to absorb 6 times as much thermal energy (heat) to have the same temp as the ground. So oceans heat and cool slower than solid ground. (Activity)
Water vapor and the water cycle help control the rate of which air temp changes.
There are gradual temp changes per season which benefit life
See Table p. 529

6. Water on Earth
About 70% of Earth’s surface is covered by water. Most of it is in oceans. Only 3% of it is fresh water (not salty)-found in the ground (groundwater), icebergs/caps, and glaciers. As glaciers break off & mix with salty sea water, the amount of freshwater is expected to decrease. 1% of Earth’s water is in lakes, swamps, and in the atmosphere (water vapor-gas).
Hydrosphere is all the water on and below Earth’s surface and in the atmosphere.

7. Solid, Liquid, and Gas
ONLY substance that exists in nature as a solid, liquid, and gas is water.
Physical reaction converts it from solid, liquid, and gas. Thermal energy is either absorbed or released during the change.
This process is referred to as the water cycle - evaporation, precipitation, and condensation.

8. Water Cycle
Natural process of water continually moving throughout the hydrosphere
Two main factors: sun and gravity - cause the water cycle
All water flows toward the ocean
Water even evaporates from leaves of plants- transpiration
Reservoirs collect runoff water due to gravity pulling it down See p

9. Evaporation & Transpiration
Water evaporates from land and bodies of water because energy from the sun breaks the bonds between water molecules
Evaporation and transpiration put water molecules back into the atmosphere
Reservoirs like lakes, oceans, and glaciers are large storage areas of water
Evaporation-liquid to gas in atmosphere; Condensation-gas cooled to liquid droplets in clouds; Precipitation-forms of liquid returning to Earth thanks to gravity

10. 15.2 Properties of Water Mini Lab p. 537 Penny Water
Water has unusual properties (characteristics) thanks to polarity
They all develop from molecules interacting with one another - polarity

11. Polar molecules H2O
Show periodic chart. Atoms are smallest pieces of matter. More than one atom forms a molecule.
Oxygen atom has negative charge while hydrogen has a positive charge so water molecules are neutral (not positive or negative). Note: opposite charges
Polarity is when opposite ends of a molecule have opposite charges creating a neutral charge. Polar molecules have opposite charges and can attract one another. Neg oxygen atom attracts Pos hydrogen atom of another molecule causing molecules to stick together. Allows drops to form larger drops.

12. Solvents
Polarity makes water the universal solvent meaning many substances can dissolve in water.
All atoms are positive, negative, or neutral. Atoms with positive charges are attracted to oxygen negative charge in water. Atoms with negative charges are attracted to hydrogen positive charge in water. This causes other atoms to break apart/dissolve.

13. Cohesion & Adhesion
Cohesion is an attraction among molecules that are alike. Ex: water sticking to water
Adhesion is an attraction among molecules that are not alike. Ex: water sticking to other surfaces
They both have to do with the stickiness of water molecules.
See pics p. 539

14. Density
Density increases when particles get close together (compacted/frozen).
A cube of ice has fewer molecules than the same amount of liquid water. See graphs on p. 541
Density of ice is lower than water because water molecules at 4 degrees Celsius spread apart to form a 6 sided pattern with space between the molecules. Molecules are closer in water than ice. Picture p. 540
Large bodies of water freeze from the top to bottom.

15. 15.3 Water Quality
The chemical, biological, and physical status of a body of water, characteristics, type and number of organisms in water, and the amount of sediment in water.
These things change water quality: nature, temperature, weathering, humans, pollution, deforestation, and runoff.

16. Types of Pollution
Point source: can be traced to one location Ex: factory or sewage treatment
Nonpoint source: cannot be traced to one location Ex: runoff
All pollution leads to changes in water and aquatic animals that can increase toxins and affect drinking water and the food chain.

17. Testing Water Quality
Scientists measure gases, temp, acidity, and cloudiness of water. They also study the health of animals in the water.
Amount of oxygen is required for healthy aquatic animals. As temp increases, oxygen decreases. Ultraviolet rays damage coral reefs/animal habitats.
Nitrates (chemical in fertilizer) & acids runs into water increasing algae growth and decreasing sunlight. If algae dies, decaying uses oxygen which decreases levels in the water.

18. Turbidity Turbidity refers to the cloudiness of water
Cloudiness could come from sediments, organisms, or pollution
Light is blocked which effects the plant and animal life in the water
A Secchi disk is used to measure turbidity by dropping it lower until it is invisible Picture p. 549

19. Bioindicators Bio = Life
Bioindicators- First indicator of changes in water-Organisms that alert scientists to changes in the level of oxygen, nutrients, or pollutants in the water.
Remote Sensing is collecting data from far away. Satellites and aerial photography help monitor and compare changes.
EPA: Environmental Protection Agency-U.S. govt agency monitors our environment-including waters

20. TEST TIME Review notes Study review on p. 554
Chapter review on p
Review Workbook pages in Ch 19
Know vocabulary
Good luck! Make an A!