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Bellringer

Learn about the composition of water molecules and the properties of water, including its polarity, capillary action, surface tension, solvent abilities, specific heat, and changing states.

michaelcalhoun
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Bellringer

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Presentation Transcript

  1. Bellringer • What two elements make up one water molecule, and how many atoms of each are there?

  2. The Properties of Water • Notes

  3. The Structure of Water • Atoms join together to form molecules. A water molecule is made up of two hydrogen atoms attached to one oxygen atom. • H2O • H2 = Two hydrogen atoms • O = One oxygen atom

  4. The Structure of Water • Water is made up of polar water molecules. A polar molecule has electrically charged areas. The oxygen end of a water molecule has a negative charge. The hydrogen ends each have a positive charge. • Polar molecules are like magnets. In magnets, opposite poles attract each other. In polar molecules, atoms with opposite charges attract each other. • As a result, water molecules tend to “stick” together.

  5. Key Properties of Water • Capillary action is the combined attraction among water molecules and between water molecules and other molecules. One result of capillary action is that water rises in a tube. • Clothing the “wicks” away moisture from your body uses capillary action to pull the sweat away from your skin.

  6. Key Properties of Water • Surface tension is the tightness across the surface of water. Some insects can even walk across water because surface tension keeps them from sinking. • Droplets are a phenomenon of surface tension.

  7. Key Properties of Water • Many substances dissolve in water. A solution is a mixture that forms when one substance dissolves in another. The substance that does the dissolvingis called a solvent. Because so many substances dissolve into water, water is called the “universal solvent.” • Solvent = substance does the dissolving • Solute = substance that is dissolved

  8. Solute = Solution Solvent

  9. Key Properties of Water • Specific heat is the amount of heat needed to increase the temperature of a substance by 1°C. Different substances have different specific heats. Water needs a lot of heat to increase its temperature - therefore water has a very high specific heat.

  10. Key Properties of Water • In summer, the sun’s heat warms the land more quickly than the water (ocean). As a result, the air is warmer inland than on the coast. • The opposite effect occurs in winter - land loses heat more quickly then water, so the air above the land is cooler. • Remember these; we’ll need them again for the weather unit.

  11. Changing State • Water is the only substance on Earth that is commonly found in three different states of matter - as a gas (water vapor), a liquid (water droplets), and as a solid (water ice). • Liquid water can become a gas when it is boiled. I can also become a gas by evaporation. Evaporation is when molecules at the surface of a liquid spontaneously change into a gas. • For evaporation to occur, heat is taken away from the environment. This is a cooling process. (i.e. - sweating)

  12. Water Vapor Liquid Water

  13. Changing State • The way a gas changes into a liquid is called condensation. When you fog up a window by breathing on it, you see the effects of condensation. • For condensation of water to occur, it must have a solid surface to condense onto, such as leaves, windows, or dirt particles in the air. This is known as nucleation. • For condensation to occur, heat is released into the environment. This is a warming process.

  14. Changing State • When water freezes, water changes from a liquid to a solid. When ice melts, water changes from a solid to a liquid. • Melting takes heat away from the environment. • Freezing releases heat into the environment.

  15. Changing States • Water freezes AND melts at 0°C. • Water boils AND condenses at 100°C. • The only difference is where the heat is going.

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