CATALYST 1.Write down all the uses for water you can think of.

Objectives: SWBAT □Identify the three properties of water and explain water’s importance in life.

RECALL… What is the chemical symbol for water? H2O What is water made of? Hydrogen and Oxygen

Shared electrons Hydrogen Oxygen

Water & Its Importance Water is perhaps the most important compound in living organisms. Water makes up 70% – 95% of most organisms.

Take Notes! Why is water so important? Water makes up 70% – 95% of most organisms Topic: Properties of Water

Water Is Polar Sometimes, when atoms form bonds, they do not share the electrons equally. This is called a polar bond. A polar molecule is a molecule with an unequal distribution of charge; that is, each molecule has a positive end and a negative end. –Ex: water

Sugar Molecules Dissolving Water can dissolve many compounds, such as salt, and many other polar molecules, such as sugar.

Water has surface tension Water molecules also attract each other (hydrogen bonding) Floating on water Capillary action

Fresh morning dew on a Water Horsetail Surface tension prevents a coin from sinking: the coin is denser than water, so it cannot be floating due to buoyancy alone.

Water Resists Temperature Changes Water resists changes in temperature. Therefore, water requires more heat to increase its temperature than do most other common liquids.

Why does ice float?

Why do roads crack in places with cold winters?

Why do bottles/cans filled with water sometimes explode after sitting in the freezer?

Water Expands When It Freezes Ice is less dense than liquid water so it floats as it forms in a body of water.

Take Notes! Why is water so important? Water makes up 70% – 95% of most organisms 1.Water is polar (has a + and - end) 2.Water resists temperature changes 3.Water expands when it freezes Topic: Properties of Water Unique properties of water How do living things use water? - Maintaining temperature - Transportation in the body - Dissolving things (ex: sugars) - Digesting food, breathing, and lubricating joints

HYDROPHOBIC- water hating, when water (polar) is combined with a non polar substance Example- drops of water on a leaf OR oil in water HYDROPHILIC – water loving, when water (polar) is combined with a polar substance Example- Food, Sugars

1. Water is made from 2 different elements: positively charged _____________ and negatively charged _____________. 2. Water’s ___________ is what makes the molecules clump together into round drops and also causes the skin, or _________________ that forms on the surface of water. 3. Water is known as the ______________ solvent, which means it is good at dissolving just about anything. 4. The salt dissolved in sea water _________ the oceans freezing point. 5. Water is the main ingredient of our ________, fills our cells, and makes up about ____% of our body weight. 6. Water covers over ____% of our Earth’s surface Surface tension Oxygen stickiness universal lowers blood Hydrogen 65 70