Properties of Water 18.12- Discuss the special properties of water that contribute to Earth's suitability as an environment for life: cohesive behavior, ability to moderate temperature, expansion upon freezing, and versatility as a solvent.

Properties of Water Objective: Explain how the polarity of a water molecule contributes to its unique properties. Essential question: How are the unique properties of water contributed to polarity and hydrogen bonding?

Investigate Fill a clean, soap-free bowl with water. See if you can get 3 paper clips to float on top of the water. Keep the fourth paperclip out of the cup. What happens if you just drop it? How did you get them to float?

https://www.youtube.com/watch?v=z5Vm56Pu4hU

Four Properties of Water Cohesive Behavior (cohesion & Adhesion) Ability to moderate temperature Expanding upon freezing (density) Universal solvent

1. Cohesive Behavior: Cohesion Water is highly cohesive Co= together ex: cooperate, covalent etc. “hesion”= to stick Cohesion is the attraction of water molecules to stick together Cohesion allows for water to have surface tension Ex. Water striders don’t break the high surface tension of water, allowing them to stay on the surface

1. Cohesive Behavior: Adhesion Adhesion is the attraction of water molecules to another substance. Ad=another Adhesion allows for capillary action, which allows water to move against the force of gravity How does water get to the top of the tree if I only watered the soil?

Practice with Adhesion & Cohesion (whiteboard) What property of water does this each picture represent? 1. 2. 3.

2. Ability to Moderate Temperature It takes a lot of energy to change the temperature of water. High heat capacity In the picture, what is going to heat up and cool down faster? Land or water?

3. Expanding Upon freezing Density is how tightly packed the atoms in a substance are 1. Objects with greater/more density will sink. 2. Objects with smaller/less density will float. As a solid (ice), water molecules spread out, leaving more space between them and decreasing the density. This is why ice floats!

4. Universal Solvent Water is called the universal solvent because it can dissolve almost anything Solvent: usually a liquid; dissolves the other substance Solute: usually a solid; what is being dissolved Solution: a homogeneous mixture (looks the same throughout); formed when one substance dissolves in another

Universal solvent Water is a great solvent because the positive and negative ends act like magnets that pull apart other substances like dissolves like, water dissolves other polar molecules We know that water dissolves sugar, but that it doesn’t dissolve oil. What can we conclude about the sugar and oil molecules?? Since water is polar and it dissolves sugar, the sugar molecule must be polar. Since water doesn’t dissolve oil, the oil molecule must be nonpolar

Why does water have these unique properties? Water molecules’ Structure!!!

What is the Structure of a Water Molecule? 1. Water is composed of 1 oxygen atom and 2 hydrogen atoms. 2. The oxygen has a negative charge and the hydrogen has a positive charge. 3. The hydrogen atoms are always in the “ear” position. Draw this in your notes with the charges

Why is water polar? Polarity- The state of having 2 opposite ends water is polar Since opposites attract each other, the negative end of one oxygen atom will be near the positive ends of 2 hydrogen atoms O and H are bonded to form one water molecule with slightly (+) and (-) ends (polar covalent bonds) What else has a positive and negative end? When do we use the word polar?

How does this contribute to waters properties? Water's polarity allows it to dissolve other polar substances very easily. When a polar substance is put in water, the positive ends of its molecules are attracted to the negative ends of the water molecules, and vice versa. The polarity of water allows water to form Hydrogen Bonds

What is Hydrogen Bonding? The bond between the oxygen (O) and Hydrogen (H) atoms of different water molecules and other polar molecules The positive H is attracted to the negative O of other water molecules. Hydrogen bonds are weak allowing water to move and reform bonds often If H2O is the formula for water, what is the formula for ice? H2O cubed. 

Revisit the floating paperclip What property is causing them to float? What is allowing for that property to exist? Predict what will happen if you add soap to your cup Try floating a paper clip now that the water has soap in it. What happens?

Key Points The unique structure of the water molecule determines it’s unique properties. Polarity and Hydrogen Bonding allow for properties of water

A B D C Practice Which diagram of a water molecule is correct? Choose the answer AND explain why. A B C. Ears and correctly labeled charges D C

Digging Deeper (right side- do not need to answer) Three questions- 1 for each level Level one- list the four properties of water Level two- compare and contrast Cohesion and adhesion Level three- Identify how the shape of a water molecule contributes to its unique properties

Building Water Molecules Working with your table partner, read through the article and follow instructions to build water molecules. C- level 2 H- ask three before me A- build water molecules and then answer the discussion questions on the LEFT side of your notebook (do not write on sheet, it’s a class set!) M- remain seated in your assigned seat P- work with your partner to complete activity (17 min) Success!

Summary (write on the right side of your journal) The four properties of water are _______________, ______________, ______________ and _______________. Cohesive behavior includes both _______________ and ______________. They are similar because _______________________. However, cohesion and adhesion differ because ____________________. All four of these unique properties of water can be contributed to the shape of the water molecule. The shape is caused by ______________ which is _______________. That allows for _________________________ to form between water molecules. These bonds allow for water molecules to move and reform new bonds easily.

Exit Ticket Clear your desk of everything but a writing utensil

What type of bond takes place between adjacent water molecules? Covalent bond Ionic bond Hydrogen bond Water bond

The ability for life to survive underneath a frozen lake is made possible by Ice being more dense than water Ice being less dense than water Ice being colder than water Ice being harder than water

Why is water such a great universal solvent? Because the positive and negative charges pull apart other molecules Because water in its solid state in denser than in the liquid state Because the hydrogen atoms on a water molecule have a positive charge Because water is considered non-polar.

Shout-outs!

Properties of Water: day 2 18.12- Discuss the special properties of water that contribute to Earth's suitability as an environment for life: cohesive behavior, ability to moderate temperature, expansion upon freezing, and versatility as a solvent.

Properties of water day 2 Objective: List and describe how each of the four properties of water make it essential for life on Earth. Essential Question: How do the unique properties of water allow life to exist on Earth?

https://www.youtube.com/watch?v=z5Vm56Pu4hU

Remember…. All properties of water are caused by Polarity and Hydrogen Bonding Hydrogen Bonding- the positive hydrogen of one molecules attracts to the negative oxygen of another water molecule Polarity- having two opposite ends; positive (+) hydrogen and negative (-) oxygen

Why is water’s cohesive behavior important to life? COHESION: water molecules stick together Surface tension causes water to clump in drops rather than spreading out in a thin layer Allows very light insects to walk on water ADHESION: water molecules stick to another substance Capillary action–allows water to move through plant roots and stems and the smallest blood vessels in your body as one molecule moves up the tree root or through the capillary, it 'pulls' the others with it

Why does water density impact life? Density is how tightly packed together molecules are in a substance solid ice is LESS dense than liquid water due to expanding when freezing Floating ice will keep the water underneath warm This allows fish and other organisms to survive in the winter. What would happen to the pond life if solid ice was more dense?

Why is water’s ability to moderate temp important to life? Water’s ability to moderate temperature can protect an ecosystem from extreme temperature differences Remember it takes a lot of energy to heat water!

Why is water’s solubility important to life?  The dissolving power of water is very important for life on Earth Works like a magnet to pull apart other polar substances Wherever water goes, it carries dissolved chemicals, minerals, and nutrients that are used to support living things

KEY POINT ALL living things need water to survive!

Lab and Task cards The class will be split in half, while half the class is working in groups on the lab at the lab stations in the back, the others will be working on the property of water task cards. After 28 min we will switch. C- level 2 (group should hear you) H- raise a silent hand A- rotating through the lab or working on the P.o.W. task cards M- lab: remain at lab table and rotate on Ms Beck’s call task cards: remain seated at assigned table P: work with your group/partner to complete the lab and task cards. Success

Clear desk of everything except something to write with Exit ticket Clear desk of everything except something to write with

Shout-outs!

Properties of Water

Water Task Cards review Take out your answer key for the water task cards, lets review!

Water Brochure You are visiting another planet as an alien. This planet has no water. You’re job is to sell water to the other planet by describing at least (minimum) 6 characteristics of water that make it able to support life. For each characteristic, you should have a picture or diagram and a caption that describes the characteristic and how it helps sustain life on Earth. (At least (minimum) of 3 sentences per characteristic). C- level 1, this should be done independently H- ask three before me! Use your resources! Check your notes and the textbook as well as your classmates before me! A- Create a brochure for water, get creative with it! M- remain in assigned seat facing forward P- work on your own brochure SUCCESS

Quiz time Clear your desk if everything except something to write with! Once you are done raise your hand