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General Chemistry. Element composed of atoms Nucleus protons and neutrons electrons. General Chemistry. Molecule a group of atoms held together by chemical bonds. General Chemistry. Bonds covalent bonds form when electrons are shared. General Chemistry. Bonds

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general chemistry
General Chemistry
  • Element
    • composed of atoms
      • Nucleus
        • protons and neutrons
      • electrons
general chemistry1
General Chemistry
  • Molecule
    • a group of atoms held together by chemical bonds
general chemistry2
General Chemistry
  • Bonds
    • covalent bonds form when electrons are shared
general chemistry3
General Chemistry
  • Bonds
    • ionic bonds form by attraction between particles with opposite charges
  • H2O
  • covalent bonds hold the 2 hydrogen & 1 oxygen together
  • Water molecules have an uneven distribution of charge = polar
    • H positive
    • O negative
  • Polar nature of water leads to:
    • attraction of other water molecules
    • attraction of other charged or polar molecules
  • Hydrogen Bonds
    • form between hydrogen of one water molecule and the oxygen of another
    • cohesion

Water spider


3 states of water
3 “states” of Water
  • Solid
  • Liquid
  • Gas
  • (and it can go back and forth between these “states” many times!)
  • Universal solvent
  • Solution
    • solvent
    • solute
  • 96.5% water & 3.5% solutes
  • solutes change properties of water
  • 96.5% water and 3.5% solutes
  • The SOLUTES are: 85% Salt (Sodium Chloride) and 15% “other.”
  • Salinity
    • total concentration of all dissolved inorganic solids
    • average = 3.5% or 35 ppt (35o/oo)
  • Source of ocean’s salts
    • weathering of surface rocks
      • sodium, magnesium, calcium
    • outgassing
      • chlorine, carbon dioxide, sulfur, hydrogen
water is recycled continually between the ocean and the land
Water is recycled continually between the ocean and the land
  • The reservoirs of water include:
    • Oceans:
      • cover 60% of the northern hemisphere
      • cover 80% of the southern hemisphere
      • contain 97% of Earth’s water
    • Rivers, lakes and glaciers
    • Groundwater
      • contains a larger volume of water than all of the combined water in lakes and rivers
The hydrologic cycledescribes the exchange of water between ocean, land and atmosphere.
    • On land precipitation exceeds evaporation.
    • In the ocean evaporation exceeds precipitation.
heat vs temperature
Heat vs Temperature
  • Heat
    • energy produced by the random vibration of atoms or molecules
  • Temperature
    • an objects response to the input or removal of heat energy
heat capacity
Heat Capacity
  • the heat required to raise the temperature of 1 gram of a substance by 1oC
  • Heat capacity of water = 1 calorie
    • the highest of all known substances
  • water resists changing temperature when heat is added or removed
density and temperature
Density and Temperature
  • density of water increases as water is cooled until a maximum of 1 g/cm3 is reached at 4oC
  • the density decreases as freezing takes place
  • ice is less dense than water
seawater vs pure water
Seawater vs. Pure Water
  • Seawater has a
    • lower heat capacity
    • lower freezing point
  • density increases until freezing point is reached
    • ice is pure water & cold, salty water left behind sinks
density of water
Density of Water
  • Depends on temperature and salinity
  • density increases as temperature decreases
  • density increases as salinity increases

Temp., Salinity and Density have a complex relationship – you can

have the SAME density at different concentrations of Temp. and salinity.

density zones in the ocean
Density Zones in the Ocean
  • 1. surface zone or mixed layer
    • temperature and salinity are constant with depth
  • 2. a middle layer where density changes rapidly with depth (because of extreme env. changes) = pycnocline
    • Thermocline: temp. changes rapidly w/ depth
    • Halocline: salinity changes rapidly w/ depth
    • NOTE: These 3 zones can ALL coincide together!

3. The DEEP ZONE (80% of all ocean water) is the layer below the pycnocline (but little change occurs here).

the surface layer
TheSurface Layer
  • About 100m thick
  • Comprises about 2% of the ocean volume
  • Is the most variable part of the ocean because it is in contact with the atmosphere.
  • Is less dense than the layers below because of its lower salinity or higher temperature.
sea surface temperatures
Sea Surface Temperatures
  • Insolation and ocean-surface water temperature vary with the season.
  • Ocean temperature is highest in the tropics (25oC) and decreases poleward.
the pycnocline
The Pycnocline
  • Is transitional between the surface and deep layers.
  • Comprises 18% of the ocean basin.
  • In the low latitudes, the pycnocline coincides with the thermocline.
  • In the mid-latitudes it coincides with the halocline.
Tropical and subtropical oceans are permanently layered with warm, less dense surface water separated from cold, dense deep water by a thermocline.
    • The thermocline is a layer in which water temperature and density change rapidly.
  • Temperate regions have a seasonal thermocline and polar regions have none.
the deep layer
The Deep Layer
  • Represents 80% of the ocean volume.
  • Water in the deep layer originates at the surface in high latitudes, where it:
    • cools
    • becomes dense
    • sinks to the sea floor
    • flows equatorward across the ocean basin
density zones in the ocean1
Density Zones in the Ocean
  • 3. the deep zone
    • a cold (1 to 3oC), dense layer on the bottom
    • most of the ocean (80%)
refraction light and sound
Refraction, Light and Sound
  • Refraction: The “bending” of waves. Light and Sound are a direct result/reaction of these waves.
  • Light and Sound waves travel at DIFFERENT speeds depending upon the medium that they are in.
light in the ocean
Light in the Ocean
  • Sunlight does NOT penetrate (always) to the “bottom.” This is because of many factors such as turbidity (sediments in the water), depth and the scattering/absorption of light through a water medium.
  • Scattering determines how light is absorbed.
  • Water thus absorbs (and scatters) the light
  • PHOTIC vs. APHOTIC zones

Different wavelengths of light produce different colors. As they are

“absorbed/scattered” in the water the colors reach different depths.

Why buy a RED wetsuit?

  • Similar to light – sound “waves” travel differently through water.
  • Speed of sound in average seawater (w/ average salinity) is 1500 m/sec.

A side-scan sonar

image of the SS

Nailsea Meadow

resting on the

seabed at a depth

of 113 meters

(367 feet).

what does this mean to marine life
What does this mean to MARINE LIFE?
  • Light effects WHERE plants and animals can live.
  • Temperature effects WHERE plants and animals can live.
  • Salinity effects WHERE plants and animals can live.
  • Dissolved gases are an important factor too.
In turbid coastal waters light rarely penetrates deeper than 20m.
    • The water appears yellow to green because particles reflect these wavelengths.

Fnft: Yangtze River