catalyst 1.write down all the uses for water you can think of
TRANSCRIPT
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 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 FreezesIce 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 leafOR 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