04/18/23 Mr. Ward

Chapter 4Chapter 4

THE CHEMISTRY OF LIFE!THE CHEMISTRY OF LIFE!

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WATERWATER

WATER IS AN ESSENTIAL WATER IS AN ESSENTIAL INGREDIENT OF LIFE.INGREDIENT OF LIFE.

IT IS KNOWN AS THE UNIVERSAL IT IS KNOWN AS THE UNIVERSAL SOLVENT. ITS SOLVENT SOLVENT. ITS SOLVENT ABILITIES COME FROM ITS POLAR ABILITIES COME FROM ITS POLAR NATURE.NATURE.

MOST ALL CHEMICAL REACTIONS MOST ALL CHEMICAL REACTIONS IN ORGANISMS OCCUR IN WATER.IN ORGANISMS OCCUR IN WATER.

GroupsGroups

1. What is the chemical make-up 1. What is the chemical make-up of water?of water?

2. What type of bonds are present 2. What type of bonds are present in water?in water?

04/18/23 Mr. Ward

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Covalent BondsCovalent Bonds

Covalent bondsCovalent bonds form when two form when two atoms share one or more pairs of atoms share one or more pairs of valence electrons.valence electrons.– Give rise to discrete molecules.Give rise to discrete molecules.

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Chemistry of WaterChemistry of Water

Water molecule consists of an Water molecule consists of an oxygen atom bound to two oxygen atom bound to two hydrogen atoms by two single hydrogen atoms by two single covalent bonds.covalent bonds.

Copyright © McGraw-Hill Companies Permission required for reproduction or display

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Hydrogen BondsHydrogen Bonds

In a water molecule, both oxygen In a water molecule, both oxygen and hydrogen atoms attract and hydrogen atoms attract shared electrons in the covalent shared electrons in the covalent bonds (electronegativity).bonds (electronegativity).– Shared electrons are thus more likely Shared electrons are thus more likely

to be found near the oxygen nucleus to be found near the oxygen nucleus than near the hydrogen nuclei.than near the hydrogen nuclei.

Polar MoleculePolar Molecule - Has distinct ends, each - Has distinct ends, each with a partial charge.with a partial charge.

GroupGroup

Why is there unequal sharing of Why is there unequal sharing of electrons in a water molecule?electrons in a water molecule?

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Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Water has cohesive and Water has cohesive and adhesive propertiesadhesive properties

1. More than a cup?1. More than a cup? 2. Pennies on a slide2. Pennies on a slide 3. Plant transport3. Plant transport 4. Meniscus4. Meniscus

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GroupGroup

Explain the reason for the results Explain the reason for the results in each of the demonstrations.in each of the demonstrations.

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Copyright © McGraw-Hill Companies Permission required for reproduction or display

04/18/23 Mr. Ward

IT HELPS TO MAINTAIN IT HELPS TO MAINTAIN TEMPERATURE HOMEOSTASIS TEMPERATURE HOMEOSTASIS BY BEING ABLE TO ABSORB BY BEING ABLE TO ABSORB MUCH HEAT.MUCH HEAT.

IN HUMANS WATER ACCOUNTS IN HUMANS WATER ACCOUNTS FOR ROUGHLY TWO-THIRDS OF FOR ROUGHLY TWO-THIRDS OF OUR BODY WEIGHT.OUR BODY WEIGHT.

Mind checkMind check

1. Why does an ice cube float in 1. Why does an ice cube float in water?water?

A. because the air bubbles in the ice A. because the air bubbles in the ice make it lightermake it lighter

B. because ice is a solid and water is B. because ice is a solid and water is a liquida liquid

C. because ice has a lower densityC. because ice has a lower density D. because ice is packed tighter D. because ice is packed tighter

than waterthan water04/18/23 Mr. Ward

2. At what temperature does water 2. At what temperature does water freeze?freeze?

A. 0 degrees centigradeA. 0 degrees centigrade B. 100 degrees centigradeB. 100 degrees centigrade C. 4 degrees centigradeC. 4 degrees centigrade D. 32 degrees centigradeD. 32 degrees centigrade

04/18/23 Mr. Ward

3. Water is different than ice in that3. Water is different than ice in that A. they are made of different A. they are made of different

elementselements B. ice has a rigid lattice structureB. ice has a rigid lattice structure C. ice contains hydrogen bonds C. ice contains hydrogen bonds

while water does notwhile water does not D. water molecules in ice are more D. water molecules in ice are more

polarpolar04/18/23 Mr. Ward

4. The density of liquid water is 1.0 4. The density of liquid water is 1.0 gm/cu.cm. The density of ice is gm/cu.cm. The density of ice is closest toclosest to

A. 1.0 gm/cu.cm.A. 1.0 gm/cu.cm. B. 0.93 gm/cu.cm.B. 0.93 gm/cu.cm. C. 0.70 gm/cu.cm.C. 0.70 gm/cu.cm. D. 1.1 gm/cu.cm.D. 1.1 gm/cu.cm.

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5. Which of the following 5. Which of the following statement is not correct?statement is not correct?

A. liquid water has a partially A. liquid water has a partially ordered structureordered structure

B. water molecule are in constant B. water molecule are in constant motion forming and breaking motion forming and breaking hydrogen bondshydrogen bonds

C. ice has a rigid lattice structureC. ice has a rigid lattice structure

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04/18/23 Mr. Ward

MIXTURESMIXTURES

MIXTURES OCCUR WHEN MIXTURES OCCUR WHEN SUBSTANCES ARE PHYSICALLY SUBSTANCES ARE PHYSICALLY MIXED WITHOUT FORMING MIXED WITHOUT FORMING NEW CHEMICAL BONDS.NEW CHEMICAL BONDS.

PROPORTIONS OF PROPORTIONS OF SUBSTANCES VARYSUBSTANCES VARY

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MIXTURE DISTRIBUTION MIXTURE DISTRIBUTION PATTERNSPATTERNS

HOMOGENEOUS - SAME HOMOGENEOUS - SAME THROUGHOUTTHROUGHOUT

HETEROGENEOUS - DIFFERENT HETEROGENEOUS - DIFFERENT AMOUNTS THROUGHOUTAMOUNTS THROUGHOUT

GroupGroup

1. What are some types of 1. What are some types of mixtures?mixtures?

2 Give an least one example of 2 Give an least one example of each mixture.each mixture.

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04/18/23 Mr. Ward

SOLUTIONSSOLUTIONS

STABLE, HOMOGENEOUS STABLE, HOMOGENEOUS MIXTURES, USUALLY LIQUIDSMIXTURES, USUALLY LIQUIDS

SOLVENTSOLVENT SOLUTESOLUTE

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SUSPENSIONSSUSPENSIONS

A MIXTURE THAT SEPARATES A MIXTURE THAT SEPARATES ON STANDINGON STANDING

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COLLOIDAL DISPERSIONCOLLOIDAL DISPERSION

MIXTURE IN WHICH THE MIXTURE IN WHICH THE DISPERSED PARTICLES ARE DISPERSED PARTICLES ARE LARGE BUT DO NOT SETTLE LARGE BUT DO NOT SETTLE OUT.OUT.

MAY OCCUR IN SOLIDS, MAY OCCUR IN SOLIDS, LIQUIDS, OR GASES.LIQUIDS, OR GASES.

GroupGroup

What are some examples of What are some examples of colloids? Why are they colloids?colloids? Why are they colloids?

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ACIDS, BASES AND ACIDS, BASES AND SALTSSALTS

ACIDS ARE HYDROGEN DONORSACIDS ARE HYDROGEN DONORS BASES ARE HYDROGEN BASES ARE HYDROGEN

ACCEPTORSACCEPTORS SALTS FORM WHEN A SALTS FORM WHEN A

NEUTRALIZATION REACTION NEUTRALIZATION REACTION OCCURS BETWEEN AN ACID AND OCCURS BETWEEN AN ACID AND A BASE, NaCl IS AN EXAMPLE.A BASE, NaCl IS AN EXAMPLE.

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pH SCALEpH SCALE

SCALE GOES FROM 0 TO 14SCALE GOES FROM 0 TO 14 O-7 IS ACIDIC, 7 IS NEUTRAL, O-7 IS ACIDIC, 7 IS NEUTRAL,

AND 7-14 IS BASICAND 7-14 IS BASIC INDICATORS CHANGE COLORS INDICATORS CHANGE COLORS

WHEN DIFFERENT pH’S OCCURWHEN DIFFERENT pH’S OCCUR

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GroupsGroups

What is the reason for the change What is the reason for the change in color of the solution in the in color of the solution in the Erlenmeyer flask?Erlenmeyer flask?

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04/18/23 Mr. Ward

ORGANIC VS ORGANIC VS INORGANIC INORGANIC

COMPOUNDSCOMPOUNDS

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1. C, H, O, AND N MAKE UP 1. C, H, O, AND N MAKE UP 96.3% OF THE WEIGHT OF THE 96.3% OF THE WEIGHT OF THE HUMAN BODY.HUMAN BODY.

2. INORGANIC COMPOUNDS ARE 2. INORGANIC COMPOUNDS ARE PRIMARILY THOSE COMPOUNDS PRIMARILY THOSE COMPOUNDS THAT DO NOT CONTAIN THAT DO NOT CONTAIN CARBON, CARBON DIOXIDE AND CARBON, CARBON DIOXIDE AND WATER ARE INORGANIC.WATER ARE INORGANIC.

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3. ORGANIC COMPOUNDS 3. ORGANIC COMPOUNDS CONTAIN CARBON, HYDROGEN, CONTAIN CARBON, HYDROGEN, AND USUALLY OXYGEN.AND USUALLY OXYGEN.

4. ORGANIC COMPOUNDS ARE 4. ORGANIC COMPOUNDS ARE SOMEHOW DIRECTLY SOMEHOW DIRECTLY ASSOCIATED WITH ASSOCIATED WITH ORGANISMS.ORGANISMS.

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CHARACTERISTICS OF CHARACTERISTICS OF CARBONCARBON

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1. ATOMIC STRUCTURE OF 1. ATOMIC STRUCTURE OF CARBONCARBON– ATOMIC SYMBOL= CATOMIC SYMBOL= C– ATOMIC NUMBER=6ATOMIC NUMBER=6– ATOMIC MASS =12ATOMIC MASS =12– ELECTRON DOT CONFIGURATIONELECTRON DOT CONFIGURATION

GroupGroup

Draw the electron dot Draw the electron dot configuration for carbon on paper.configuration for carbon on paper.

04/18/23 Mr. Ward

04/18/23 Mr. Ward

2. CARBON HAS THE ABILITY 2. CARBON HAS THE ABILITY TO FORM 4 STRONG AND TO FORM 4 STRONG AND STABLE COVALENT BONDS.STABLE COVALENT BONDS.

3. CARBON CAN FORM CHAINS 3. CARBON CAN FORM CHAINS OF ALMOST UNLIMITED OF ALMOST UNLIMITED LENGTH BY BONDING TO LENGTH BY BONDING TO OTHER CARBON ATOMS.OTHER CARBON ATOMS.

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4. CARBON MAY FORM SINGLE, 4. CARBON MAY FORM SINGLE, DOUBLE, OR TRIPLE COVALENT DOUBLE, OR TRIPLE COVALENT BONDS.BONDS.

5. THE CARBON CHAINS MAY 5. THE CARBON CHAINS MAY CLOSE ON THEMSELVES TO CLOSE ON THEMSELVES TO FORM RINGS.FORM RINGS.

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POLYMERIZATION OF POLYMERIZATION OF ORGANIC COMPOUNDSORGANIC COMPOUNDS

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1. THIS PROCESS OCCURS WHEN 1. THIS PROCESS OCCURS WHEN LARGE COMPOUNDS ARE LARGE COMPOUNDS ARE CONSTRUCTED BY JOINING CONSTRUCTED BY JOINING TOGETHER SMALLER TOGETHER SMALLER COMPOUNDS.COMPOUNDS.

2. THE SMALLER COMPOUNDS 2. THE SMALLER COMPOUNDS ARE CALLED MONOMERS.ARE CALLED MONOMERS.

3. THE LARGER COMPOUNDS ARE 3. THE LARGER COMPOUNDS ARE CALLED POLYMERS.CALLED POLYMERS.

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4. VERY LARGE POLYMERS ARE 4. VERY LARGE POLYMERS ARE CALLED MACROMOLECULES.CALLED MACROMOLECULES.