Lesson 2

4 primary oceans Pacific, Atlantic, Indian, Arctic Water that fills large areas between continents = Basins 97% of water is in the ocean Only 3% is fresh Only 1% of that is liquid Much of that is in the ground Marine organisms need water 80% water by mass

Dynamic Constantly changing Water is distributed across the hydrosphere and provides life In living organisms: Maintains body structure 80% water by mass Carries dissolved materials through the organism Carries out chemical rxs  Life processes

Important resource for us Source of food, transportation, energy, etc Replenishes itself naturally over short periods It is a RENEWABLE resource Influx from river and precipitation Weathering, transport of sediments, weather, climate, storing and distributing heat in the ocean Gas and oil are nonrenewable resource Don’t replenish quickly

Although renewable, we have to keep in mind how much of the resource we use Overfishing is one of the largest problems facing ocean ecosystems Fish are killed quicker than they can reproduce and grow Have to be kind to our water, but first we need to understand water!

Watch Mission Blue Present a product of the major points of the movie

Matter is anything that takes up space and has mass. All matter, living or nonliving, is made up of elements. Elements contain atoms. An atom is the smallest unit of matter that can enter chemical reactions. 9

Atoms have a central nucleus made up of protons and neutrons, and shells around the nucleus in which electrons orbit. inner energy shell holds two electrons outer energy shell holds eight electrons Electrons in outer shell are VALENCE electrons The number of electrons in the outer energy shell determines the chemical properties of the atom. 10

Neutron (o) Neutral subatomic particle found in the nucleus Proton (+) Positively Charged subatomic particle in the nucleus Electron (-) Negatively charged subatomic particle outside the nucleus These can be distinguished by their mass, charge and location in an atom

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Atoms have an atomic symbol, atomic number, and atomic mass. Some atoms differ in their number of neutrons and are called isotopes. Carbon has 3 isotopes: Carbon 12 (most abundant) Carbon 13 Carbon 14 (radioactive - unstable) 13

Atoms form bonds to fill the outer shell with electrons. When atoms bond with other atoms, molecules are formed. When atoms of different elements bond, a compound is formed. Two types of bonds are ionic bonds and covalent bonds. 14

In ionic bonding, atoms give up or accept electrons, resulting in ions. Ions with opposite charges (- or +) are attracted to each other and form an ionic bond. 15

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17 Ions can have important biological functions.

In covalent reactions, atoms share electrons, resulting in covalent bonds. 18

Because of the angles of its chemical bonds, the oxygen atom is on one end of the molecule and the hydrogen atoms are on the other. With 8 protons in its nucleus, an oxygen atom has a much stronger attraction for electrons than does a hydrogen atom with its single proton.

There is a greater probability of finding the shared electrons in water close to its oxygen atom than near its hydrogen atoms. As a result, the oxygen end of the molecule has a slight negative charge and the hydrogen end of the molecule has a slight positive charge.

Because of their partial positive and negative charges, polar molecules such as water can attract each other. The attraction between a hydrogen atom on one water molecule and the oxygen atom on another is known as a hydrogen bond.

Water is able to form multiple hydrogen bonds, which account for many of its special properties. Hydrogen bonds are not as strong as covalent or ionic bonds, and they can form in other compounds besides water.

Because of the multiple hydrogen bonds between water molecules Large amount of heat energy required to cause those molecules to move faster and raise the temperature of the water. Large bodies of water, such as oceans and lakes, can absorb large amounts of heat with only small changes in temperature. This protects organisms living within from drastic changes in temperature.

High cohesion = high surface tension Provides surfaces of water with think film-like covering, allowing water droplets to forms and organisms to use as habitat

Record your hypothesis for each demonstration Draw and label results How does this relate to what you know about the oceans?

Reversible physical change that occurs when a substance changes from one state of matter to another

Melting – solid to liquid Freezing – liquid to solid Vaporization – liquid to gas Condensation – gas to liquid Sublimation – solid to gas Deposition – gas to solid

The temperature of a substance DOES NOT change during a phase change!! i.e. The temperature changes while either completely solid, liquid or gas Energy is either absorbed or released Endothermic – energy is absorbed Exothermic – energy is released Higher altitude = Lower required temps

The temperature of a substance DOES NOT change during a phase change!! Energy is used to change molecule position

Solid to Liquid Endothermic Molecules move from fixed positions

Water = 0° C (32 ° F) Seawater Higher or lower? Liquid to Solid Exothermic Molecules are “frozen” to a fixed position In the ocean, the water loses heat and thus the top layer freezes Colder on top than below Survival of fish?

Water = 100 ° C (212 ° F) Liquid to Gas Endothermic Boiling & Evaporation Vapor pressure increases as temperature increases In the ocean, heat is absorbed by water and ice melts

Gas to Liquid Exothermic

Higher Boiling Point Lower freezing Point Salt interacts with water to make it less “organized”

Freshwater density = 1.00g/cm 3 Saltwater density = 1.03 g/cm 3 Why higher? Volume is the amount of space taken up by an object. Density is the ratio of an object’s mass to its volume:

The forces from pressure acting on the bottom of this golf ball are greater than those on the top. This produces a net force— called the buoyant force—that acts upward on the ball.

Buoyancy is the ability of a fluid to exert an upward force on an object placed in it. Buoyancy results in the apparent loss of weight of an object in a fluid. A submerged object pushes aside, or displaces, a volume of fluid equal to its own volume. A floating object displaces a volume equal to the volume of the part of the object that is submerged.

How can you determine if an object will float or sink in a fluid? If an object is less dense than the fluid it is in, it will float. If the object is more dense than the fluid it is in, it will sink. Buoyant force Weight Buoyant force Weight Buoyant force Weight

Two forces act on every object in a fluid—weight and the buoyant force. The force of gravity, equal to the object’s weight, acts downward on the object. The buoyant force, equal to the weight of the volume of displaced fluid, acts upward on the object.

Suspended An object that has the same density as the fluid it is submerged in will be suspended (it will float at any level) in the fluid. The buoyant force acting on the suspended object exactly equals the object’s weight. Submarines and some fish are able to suspend themselves in water partly by adjusting their density. Neutral Buoyancy = Preventing movement up or down

Floating A solid piece of steel sinks in water. A heavy steel ship floats because of the shape of its hull. The hull is shaped so that it displaces a large volume of water, creating a large buoyant force.

The weight and buoyant force determine if an object sinks or floats. Buoyant force Weight Buoyant force Weight Buoyant force Weight

Objects also float more easily in dense fluids. The denser the fluid is, the greater is the weight displaced. The greater displaced weight results in a greater buoyant force. This is why it is easier for a person to float in very salty water. The dense salty water produces a larger buoyant force when displaced by the person's body. Displace less water

Explain the relationship that salinity, temperature, density, and pressure have to the ocean and its currents.