Chemistry of LifeChemistry of LifeChapter 3Chapter 3

BiologyBiology

Mr. GilbertsonMr. Gilbertson

AtomsAtoms Smallest particle of matter which still Smallest particle of matter which still

retains the property of that material.retains the property of that material. Made up of smaller particlesMade up of smaller particles Mostly made up of empty spaceMostly made up of empty space So small that they cannot be seen even So small that they cannot be seen even

with the most powerful microscopeswith the most powerful microscopes Atoms an element are unique to that Atoms an element are unique to that

element but similar to all other atoms of element but similar to all other atoms of that elementthat element

ElementsElements Any material that is made up of only one kind Any material that is made up of only one kind

of atomof atom Examples: iron, carbon, gold, oxygen, lead, Examples: iron, carbon, gold, oxygen, lead,

silver, etc.silver, etc. There are 90 naturally occurring elementsThere are 90 naturally occurring elements 13 are man made13 are man made Total 103 elements listedTotal 103 elements listed Each is represented by an atomic symbolEach is represented by an atomic symbol

CHEMICAL BONDINGCHEMICAL BONDING

All atoms need to have a full outer All atoms need to have a full outer energy level, filled with electrons to be energy level, filled with electrons to be stable. (for most 8 electrons)stable. (for most 8 electrons)

Atoms with less than a full outer energy Atoms with less than a full outer energy level will react (lose, gain, or share level will react (lose, gain, or share electrons) with other atoms, to fill the electrons) with other atoms, to fill the outer energy level and become stable.outer energy level and become stable.

COVALENT BONDSCOVALENT BONDS When two or more atoms share electrons to When two or more atoms share electrons to

form a moleculeform a molecule A molecule is a group of atoms held together A molecule is a group of atoms held together

by covalent bondsby covalent bonds All organic molecules are covalently bonded All organic molecules are covalently bonded

and made up of molecules (molecular)and made up of molecules (molecular) Normally the number of electrons and protons Normally the number of electrons and protons

is the same in a molecule so they are usually is the same in a molecule so they are usually neutral in terms of charge.neutral in terms of charge.

Sometimes the electrons are more strongly Sometimes the electrons are more strongly attracted to one end of a molecule, it is said attracted to one end of a molecule, it is said to be polarto be polar

HYDROGEN BONDINGHYDROGEN BONDING Electrons are shared between atoms, but Electrons are shared between atoms, but

sometimes they are more attracted to one of sometimes they are more attracted to one of the bonded atoms than the other. the bonded atoms than the other.

This forms a slight difference in charge from This forms a slight difference in charge from one end of a molecule (Hone end of a molecule (H22O) to the other. O) to the other.

It is said to have poles, or to be polarIt is said to have poles, or to be polar Allows molecules to attract one another, Allows molecules to attract one another,

opposite charges attract, like charges repelopposite charges attract, like charges repel Called hydrogen bonding – weak form of Called hydrogen bonding – weak form of

chemical bondingchemical bonding

IONIC BONDINGIONIC BONDING Ions are atoms that are charged due to a loss Ions are atoms that are charged due to a loss

or gain of electronsor gain of electrons Atoms with less than three electrons in the Atoms with less than three electrons in the

outer energy level tend to lose electrons (they outer energy level tend to lose electrons (they form positive ions)form positive ions)

Atoms with five or more electrons tend to gain Atoms with five or more electrons tend to gain electrons (they form negative ions)electrons (they form negative ions)

When two oppositely charged ions are When two oppositely charged ions are attracted to one another (one positive and attracted to one another (one positive and one negative) an ionic bond is formed.one negative) an ionic bond is formed.

The bond between sodium (Na) and chlorine The bond between sodium (Na) and chlorine (Cl) is an ionic bond.(Cl) is an ionic bond.

WATERWATERMOSTMOST IMPORTANTIMPORTANT MOLECULEMOLECULE TOTO LIFELIFE

INORGANIC MOLECULE UNIQUE PROPERTIES

POLAR MOLECULE

EFFECTIVE SOLVENT

STRONG ADHESION

STRONG COHESION

RESULTS IN CAPILLARY

MOVEMENT

HIGH SPECIFIC HEAT

COHESION OF WATERCOHESION OF WATER

O

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O

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-O

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O

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O

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O

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O

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O

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O

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O

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- O

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- O

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O

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O

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O

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WATER FORMS AN ORGANIZED PATTERN OF MOLECULESALL OF WHICH ARE ATTRACTED TO EACH OTHER

COHESION OF WATERCOHESION OF WATER Caused by hydrogen bonding Caused by hydrogen bonding Cohesion refers to the attraction between Cohesion refers to the attraction between

molecules of the same substancemolecules of the same substance Enables water to form a thin film or a dropEnables water to form a thin film or a drop Molecules at the surface are linked tightly so Molecules at the surface are linked tightly so

they form a “skin” known as surface tensionthey form a “skin” known as surface tension Surface tension prevents water surface from Surface tension prevents water surface from

stretching or breaking easily.stretching or breaking easily. Requires more energy to evaporate.Requires more energy to evaporate.

ADHESION OF WATERADHESION OF WATER The attraction of molecules of different The attraction of molecules of different

substancessubstances Water is attracted to solid surfaces.Water is attracted to solid surfaces. Causes some surfaces to get “wet”Causes some surfaces to get “wet” Adhesion powers the process of capillary Adhesion powers the process of capillary

action in which water moves upward in action in which water moves upward in narrow tubes such as plant stemsnarrow tubes such as plant stems

The attraction due to adhesion is stronger The attraction due to adhesion is stronger than the force of gravity so the water “climbs” than the force of gravity so the water “climbs” the tube. (Max height is 32ft or 9.8m)the tube. (Max height is 32ft or 9.8m)

High Specific Heat of WaterHigh Specific Heat of Water

Water absorbs heat more slowly than Water absorbs heat more slowly than other substancesother substances

Organisms are able to get rid of excess Organisms are able to get rid of excess heat by evaporation of water (sweat)heat by evaporation of water (sweat)

Enables organisms to maintain a Enables organisms to maintain a constant temperature even in a constant temperature even in a changing environment.changing environment.

Helps maintain homeostasisHelps maintain homeostasis

AQUEOUS SOLUTIONSAQUEOUS SOLUTIONS Water is called the universal solventWater is called the universal solvent Almost anything will dissolve in water to some Almost anything will dissolve in water to some

extentextent A solution is a mixture in which one or more A solution is a mixture in which one or more

substances are uniformly distributed in substances are uniformly distributed in another (kool-aid)another (kool-aid)

Many important substances in the body are Many important substances in the body are dissolved in blood or other body fluidsdissolved in blood or other body fluids

Any solution in which one of the components Any solution in which one of the components is water is said to be an aqueous solution.is water is said to be an aqueous solution.

Aids in transportation of materials within cells Aids in transportation of materials within cells and within organismsand within organisms

POLARITY OF WATERPOLARITY OF WATER

O

H

H

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+

-

THE POLARITY OF WATER IS CAUSED BY THE UNEQUAL DISTRIBUTION OF ELECTRONS, SINCE THE ELECTRONSSTAY WITH THE OXYGEN IT TENDS TO HAVE A SLIGHTLYNEGATIVE CHARGE

POLARITY OF WATERPOLARITY OF WATER Enables water to dissolve a great number of Enables water to dissolve a great number of

organic compounds (polar molecules)organic compounds (polar molecules) Enables water to dissolve ionic compounds Enables water to dissolve ionic compounds

(mineral ions)(mineral ions) Nonpolar molecules do not dissolve well in Nonpolar molecules do not dissolve well in

water they tend to clump.water they tend to clump. The nonpolar cell membrane tends to form a The nonpolar cell membrane tends to form a

boundary past which polar water molecules boundary past which polar water molecules cannot easily pass.cannot easily pass.

ACIDS AND BASESACIDS AND BASES In water there are some molecules which will In water there are some molecules which will

dissociate into ions dissociate into ions HH++ ( (Hydronium ionHydronium ion) and ) and OHOH-- ((Hydroxide ionHydroxide ion))

Any solution which produces a higher than normal Any solution which produces a higher than normal concentration of concentration of HH++ ions is called an ions is called an AcidAcid

Any solution which produces a higher concentration Any solution which produces a higher concentration of (of (OHOH--) ions is a base or alkaline solution.) ions is a base or alkaline solution.

pHpH is a measure of the inverse H is a measure of the inverse H++ ion concentration ion concentration A A pHpH of 7 is neutral, a of 7 is neutral, a pHpH of less than 7 is acid, and of less than 7 is acid, and

a a pHpH greater than 7 is a greater than 7 is a BaseBase If you add an acid and a base they will neutralizeIf you add an acid and a base they will neutralize