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Chapter 6 Water. © 2006 Brooks/Cole, a division of Thomson Learning, Inc. The Water Molecule Is Held Together by Chemical Bonds A water molecule is composed.

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Presentation on theme: "Chapter 6 Water. © 2006 Brooks/Cole, a division of Thomson Learning, Inc. The Water Molecule Is Held Together by Chemical Bonds A water molecule is composed."— Presentation transcript:

1 Chapter 6 Water

2 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. The Water Molecule Is Held Together by Chemical Bonds A water molecule is composed of two hydrogen atoms and one oxygen atom. Water is a polar molecule, having a positive and a negative side. A molecule is a group of atoms held together by chemical bonds.

3 Fig. 6-1, p. 155 Two hydrogen atoms... share their electrons with one oxygen atom... to form a water molecule held together by covalent bonds... which acts as if it has negative and positive ends. Nucleus (+1 unit of charge) Electron (–1 unit of charge) Stepped Art 2 – 105°

4 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Water’s Chemical Bonds Cohesion – the ability of water molecules to stick to each other, creating surface tension. Adhesion – the tendency of water molecules to stick to other substances

5 © 2006 Brooks/Cole, a division of Thomson Learning, Inc.

6 Heat Capacity Water has a very high heat capacity, which means it resists changing temperature when heat is added or removed.

7 © 2006 Brooks/Cole, a division of Thomson Learning, Inc.

8 Water Becomes Less Dense When It Freezes Because molecules of liquid water are packed less efficiently, ice is less dense than liquid water and floats.

9 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Water Removes Heat from Surfaces As It Evaporates This cools the air and affects global temperatures.

10 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Coastal Communities have milder temperatures than inland communities.

11 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Ocean-Surface Conditions Depend on Latitude, Temperature, and Salinity Average surface temperature and salinity for the world ocean. As you would expect, temperatures are lowest in the polar regions and highest near the equator. Heavy rainfall in the equatorial regions “freshens” the ocean near the equator, whereas hot and dry conditions near the tropic lines (Tropic of Capricorn and Tropic of Cancer) result in higher surface salinity in those areas.

12 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Sea-surface average salinities in parts per thousand (‰).

13 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. The Ocean Is Stratified into Three Density Zones by Temperature and Salinity Surface zone – the upper layer of the ocean, containing the least dense water. The surface zone is only about 2% of total ocean volume.

14 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Pycnocline – a zone in which density increases with depth, containing about 18% of all ocean water Deep zone – contains about 80% of all ocean water. There is little change in density throughout this layer.

15 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Fig. 6-18b, p. 169 Pycnoclineis also aThermocline 0Surface zone Pycnocline 3, ,562 9,843 Depth (ft) 2 Depth (km) 3 Deep zone 13,124 4 DensityTemperature (°C) Vertical density and temperature profiles compared

16 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Fig. 6-18a, p. 169 Surface zone 2% of ocean water 80% of ocean water Pycnocline 18% of ocean water Deep zone Depth (km) The density zones Increasing latitude (north or south)

17 © 2006 Brooks/Cole, a division of Thomson Learning, Inc.

18 Sound and light both travel in waves: Refraction is the bending of waves

19 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Sunlight does not travel well in the ocean. Scattering occurs when light is bounced between air and water molecules, dust and other objects. Absorption occurs when light’s electromagnetic energy is converted to heat in the molecules of seawater.

20 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Water Transmits Blue Light More Efficiently Than Red Only a thin film of seawater is illuminated by the sun. Except for light generated by living organisms, most of the ocean lies in complete blackness. (a) The table shows the percentage of light absorbed in the uppermost meter of the ocean and the depths at which only 1% of the light of each wavelength remains. (b) The bars show the depths of penetration of 1% of the light of each wavelength (as in the last column of the table)

21 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Fig. 6-22c, p. 173

22 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Fig. 6-22d, p. 173

23 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Sound in the Ocean Sound Travels Much Farther Than Light in the Ocean

24 © 2006 Brooks/Cole, a division of Thomson Learning, Inc. Fig. 6-23, p. 174


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