DO NOW

•HOW DO WE USE WATER IN OUR EVERY DAY LIVES?

•WHY IS WATER ESSENTIAL TO LIFE?

• PLEASE TURN IN YOUR OUTLINE IN THE BIN ON MY DESK.

OBJECTIVES

• TO OBSERVE THE DIFFERENT PROPERTIES OF WATER AND ATTEMPT TO EXPLAIN WHY AND HOW THESE PROPERTIES OCCUR.

WATER PROPERTIES LAB

• GET WITH YOUR ASSIGNED LAB PARTNER.

• FOLLOW THE DIRECTIONS CAREFULLY FOR EACH PART OF THE LAB. BE SURE TO ANSWER ALL QUESTIONS.

• THE COMPLETED LAB WILL BE DUE NEXT LAB DAY AND YOU WILL ALSO HAVE A SHORT QUIZ ON THE LAB.

• *YOU WILL HAVE A SHORT SAFETY QUIZ TOMORROW AT THE START OF CLASS.

DO NOW

• WHAT IS THE CHEMICAL FORMULA FOR WATER?

• WHAT DOES A MOLECULE OF WATER LOOK LIKE?

• WHAT ARE SOME OF THE PROPERTIES OF WATER?

OBJECTIVES

• TO IDENTIFY WAYS IN WHICH THE STRUCTURE OF WATER CONTRIBUTES TO ITS FUNCTION.

• TO EXPLAIN THE VARIOUS PROPERTIES OF WATER AND GIVE EXAMPLES OF HOW THEY ARE SHOWN IN LIVING THINGS.

WATER AND IT’S PROPERTIES

2.1- 2.18

LET’S REFRESH…

• EVERYTHING AROUND US IS MADE UP OF ATOMS OF DIFFERENT ELEMENTS.

• ATOMS CONSIST OF 3 SUBATOMIC PARTICLES

• PROTONS +

• NEUTRONS

• ELECTRONS -

• THE ELECTRON ARRANGEMENT OF AN ATOM DETERMINES IT’S CHEMICAL PROPERTIES

• ATOMS OF DIFFERENT ELEMENTS BONDED TOGETHER CAN FORM COMPOUNDS

• EX: H20, NACL

THE WATER MOLECULE

• CHEMICAL FORMULA= H2O

• WHAT DOES IT LOOK LIKE?

O

H H

THE WATER MOLECULE

• HYDROGEN AND OXYGEN ARE COVALENTLY BONDED AND SHARE THEIR OUTER ELECTRONS.

• 2 ATOMS THAT SHARE ELECTRONS EQUALLY ARE SAID TO BE NONPOLAR.

• CERTAIN ELEMENTS HAVE A BIGGER “PULL” (HIGHER ELECTRONEGATIVITY) ON ELECTRONS AND CAUSE AN UNEQUAL SHARING OF THE ELECTRONS MAKING THEM POLAR.

HYDROGEN BONDS

• DUE TO THE PARTIAL +CHARGE OF THE HYDROGEN ATOMS, WATER IS ABLE TO HYDROGEN BOND TO OTHER ATOMS THAT ARE SLIGHTLY NEGATIVE, LIKE ITSELF.

• HYDROGEN BONDS ARE WEAK BUT VERY IMPORTANT!

SO HOW IS THIS POSSIBLE?

THE DROP…

• COHESION: CAUSES WATER TO FORM DROPS

• SURFACE TENSION: CAUSES THE DROP TO BE SPHERICAL

• ADHESION: KEEPS THE DROP ON THE LEAF

COHESION

• WATER MOLECULES ARE ABLE TO “STICK” TO EACH OTHER

• THIS PROPERTY HELPS PLANTS TRANSPORT WATER.

ADHESION• A SUBSTANCE’S ABILITY TO ADHERE

OR “CLING” TO ANOTHER SUBSTANCE.

• ADHESION OF WATER TO THE WALLS OF THE PLANT’S VEINS HELP COUNTER GRAVITY!

ADHESION

• WHY DID THE WATER DRIP RIGHT OFF THE WAX PAPER?

ADHESION

• WATER IS POLAR AND WILL ONLY ADHERE TO OTHER POLAR MOLECULES.

• WAX PAPER IS NONPOLAR SO IT DOESN’T “STICK” TO IT. IF YOU PUT A NONPOLAR SUBSTANCE ON IT LIKE VEGETABLE OIL, IT WILL STICK!

ADHESION +COHESION

• THE PROPERTIES OF BOTH ADHESION AND COHESION GIVE US CAPILLARY ACTION.

• WATER “CLIMBS UP” THE SIDES OF TUBES BY ADHESION AND COHESION PULLS ALONG THE REST OF THE MOLECULES.

CAPILLARY ACTION

• TEARS ARE PRODUCED CONSTANTLY TO PROTECT YOUR EYE BUT YOU ARE NOT ALWAYS CRYING AND EXPELLING THESE TEARS (YOUR EYES WATER ALL OF THE TIME WITHOUT DROPPING TEARS DOWN YOUR CHEEK!). BASED ON THE PICTURE TO THE LEFT, EXPLAIN HOW THIS IS POSSIBLE?

SURFACE TENSION

• HYDROGEN BONDS GIVE WATER A HIGH SURFACE TENSION. (MEASURE OF HOW DIFFICULT IT IS TO STRETCH OR BREAK THE SURFACE OF A LIQUID).

SURFACE TENSION

• WHAT DID THE SOAP DO TO THE WATER ON THE PENNY?

• WHAT CAN YOU CONCLUDE ABOUT THE MOLECULAR STRUCTURE OF THE SOAP?

• WHY DO WE USE SOAP AND WATER TO CLEAN THINGS?

EXIT SLIP

• WHY DOES THE WATER DROPLET TO THE RIGHT GROW BEFORE DROPPING INTO THE GRASS? WHY DOESN’T IT JUST ROLL OFF OF THE LEAF? EXPLAIN USING ALL OF THE TERMS WE HAVE JUST GONE OVER.

DO NOW