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Unformatted text preview: 1 Chapter 6 Chapter 6 Water and Ocean Structure Water and Ocean Structure Some basic concepts: Compounds substances that contain two or more different elements in fixed proportions Element a substance composed of identical particles that cannot be chemically broken down into simpler substances Atoms the particles that make up elements 2 A water molecule is composed of two hydrogen (H) atoms and one oxygen atom (O 2 ). A molecule is a group of atoms held together by chemical bonds. Water is a polar molecule, having a positive and a negative side. Chemical bonds, the energy relationships between atoms that hold them together, are formed when electrons- tiny negatively charged particles found toward the outside of an atom - are shared between atoms or moved from one atom to another. 3 H 2 O Covalent bonds : shared pairs of electrons Hydrogen bonds : bonds between water molecules due to polar structure 4 Hydrogen bonds form when the positive end of one water molecule bonds to the negative end of another water molecule. Two important properties of water molecules: 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 Hydrogen Bonds 5 Temperature, Heat, Heat Capacity, Calories, etc. Temperature Measure of av. kinetic energy (motion) of molecules (KE=1/2mv 2 ) unit is degrees C, F or K (Kelvin) Heat Measure of the total kinetic energy of the molecules in a substance Unit is the calorie * Heat Capacity = is a measure of the heat required to raise the temperature of 1g of a substance by 1 C. * Calorie = amount of heat to raise temperature of 1 gram of pure water by 1C (from 14.5 C to 15.5 C) * Latent Heat 6 Not All Substances Have the Same Heat Capacity Water has a very high heat capacity, which means it resists changing temperature when heat is added or removed large thermal inertia 2 7 Remember from Chapter 3? Density is a key concept for understanding the structure of Earth differences in density lead to stratification (layers). Density measures the mass per unit volume of a substance. Density = _Mass_ Volume Density is expressed as grams per cubic centimeter. (pure) Water has a density of 1 g/cm 3 Granite Rock is about 2.7 times more dense just about everything in this course! Temperature affects waters density 8 The relationship of density and temperature for pure water. Note that points C and D both represent 0C (32F) but different densities and thus different states of water. Ice floats because the density of ice is lower than the density of liquid water....
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This note was uploaded on 07/18/2011 for the course EARTH SCIE 180 taught by Professor Frankbuonaiuto during the Spring '11 term at CUNY Hunter.
- Spring '11