The Hydrosphere. Chapters 2 4 Holt Science

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1 The Hydrosphere Chapters 2 4 Holt Science

2 AHA Question Pages If water is one of the most common substances on Earth, what makes it so unique?

3 Page 145 CO: SWBAT identify and describe the properties of water. LO: SWBAT compare cohesion and adhesion.

4 Imagine Picture yourself canoeing down a gentle stream on a beautiful sunny afternoon. You can see the gravelly stream bottom through the crystal blue water.

5 All of a sudden, the silence is broken by the sound of rushing water. You notice that the current has picked up and the water is moving much faster. What is happening?

6 In the distance you see some large boulders and a waterfall. Unexpectedly, the canoe hits a rock and nearly topples over. What forces of nature could cause the stream to change so drastically?

7 Essential Questions What are the properties of water? How does moving water shape the Earth? How does erosion and deposition shape the land? From where does our drinking water come? How do humans impact the water supply?

8 Brainstorming What do you know about water? From where does your drinking water come? How do you impact the water supply?

9 Video Clip

10 What did you learn?

11 Water Covers nearly 70% of Earth s surface Most abundant substance on Earth Most important substance to organisms Unique properties that help to support life on Earth

12 Water Molecules and Polarity Made up of two hydrogen and one oxygen Hydrogen shares an electron with oxygen Oxygen attracts electrons more strongly than hydrogen Oxygen pulls the shared electrons closer to its nucleus Makes charges unequal, called polarity

13 Polarity Causes water molecules to attract each other Like weak magnets Positive pole on hydrogen attracts negative pole on oxygen Forms temporary bonds that form and break easily called a hydrogen bond Helps water stick together

14 Cohesion and Adhesion Cohesion is the tendency for water molecules to form weak bonds and stick together Surface tension a force that acts on the particles at the surface of the liquid Forms a kind of skin on the water

15 Water Strider

16 Jesus Lizard

17 The tendency of water to stick to other substances Adhesion

18 Universal Solvent A solvent is a substance in which another substance dissolves Water is called the universal solvent because it can dissolve more substances than any other known substance Due to its polarity

19 Density Measure of the mass of a substance per unit volume Changes with temperature Pour cold water into hot water Cold water sinks to bottom Changes with change in state Ice floats in water

20 Buoyancy Ability of a fluid to exert an upward force, called the buoyant force, on an object that is immersed in the fluid Property that allows organisms to float

21 Boats If metals sink in water, why is a metal boat able to float?

22 Boats It is able to float because its shape provides areas that can fill with air, which is less dense than water. The air helps to lower the density of the entire boat, which, in turn, allow the buoyant force of the water to keep the boat afloat.

23 Specific Heat The amount of energy needed to raise the temperature of 1 kg of a substance by 1 C Specific heat of water J/kg C Allows lakes, streams, and ocean ecosystems to maintain stable temperatures Helps your body to maintain a constant internal environment

24 Capillary Action The tendency of water to rise Paper towel absorbency Straw

25 Review Which form of water has the highest density? A. Ice B. Warm water C. Cold water D. Water vapor

26 Question 2 How are nutrients transported in water? A. As compounds B. As ions C. As molecules D. As solids

27 Question 3 Which of the following describes the tendency of a water molecule to stick to other water molecules? A. Cohesion B. Density C. Adhesion D. Buoyancy

28 Question 4 The diagram below shows a water molecule.

29 Question 4, cont. What do the charges on either end of the molecule indicate about the molecule? A. Water is a polar molecule. B. Water is a nonpolar molecule. C. Water is an ionic compound. D. Water is an ion.

The Properties of Water

The Properties of Water Water has many unique properties that allow it to support life on earth. Water is so important to life that scientists look for water on other planets to determine if that planet