Ms Imai

Lee High School

Unit 2: Let’s Get Tiny

In your notes write a paragraph responding to the prompt below.

Warm-Up

Do you think these pictures are real or tricks? Why do you think the first one is real or not?Why do you think the second one is real or not?

•Take a cup and an index card from your bin.•Fill the cup about 1/4 of the way full of water.•Put the index card on top of the cup.•Hold the card tightly and turn the cup over, keep the cup over your water bin!•Carefully let go of the index card.

Clean up: throw the index card away. Pour the water back in the bottle. Put everything back into the bin

Water is Wonder-full!1. Structure

A. Each water molecule has three atoms

1. One atom of Oxygen

2. Two atoms of Hydrogen

8p 8n

1p 0 n 1p 0 n

B. Polar Covalent Bonds1. Water shares covalently2. BUT water doesn’t share equally!3. Oxygen pulls the electrons closer

than hydrogen cana. This gives oxygen a slightly Negative chargeb. and it gives hydrogen a slightly positive charge

8p 8n

1p 0 n1p 0 n

My e-!

δ-

δ+δ+

This is called a POLAR COVALENT BOND

B. Polar Covalent Bonds4. the slightly charged H20 molecules

act like magnets. They are attracted to each other.

8p 8n

1p 0 n1p 0 n δ+δ+

δ-

8p 8n

1p 0 n

1p 0 n

δ +

δ +

δ -

8p 8n

1p 0 n1p 0 n

δ+δ+

δ-

8p 8n

1p 0 n1p 0 n δ+δ+

δ-5. When the charged atoms pull together it forms a bond called a Hydrogen bond.

B. Polar Covalent Bonds6.When the water molecules form hydrogen bonds, they stick together.

This is known as COHESION

This is why bubbles are round! The water molecules pull together, which makes a circle!

B. Polar Covalent Bonds7.lots and lots of cohesion causes cool stuff to happen!»a. The top layer of the water is so strong it can go above the level of the cup! Small things can even stand on water!

This force is called SURFACE TENSION

B. Polar Covalent Bonds8. the slight charges also allow water to stick to other things

like your hair, your clothes, string, glass, plastic

This force is called ADHESION

What property is keeping the water up on the side of the straw?

What property is keeping the water down in the middle of the tube?

What property is keeping the paper clip from sinking?