chapter 2 anatomy lect notes

8/2/2019 Chapter 2 Anatomy Lect Notes

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PowerPointLecture Slidesprepared byJanice Meeking,Mount Royal College

C H A P T E R

Copyright 2010 Pearson Education, Inc.

2

ChemistryComes Alive:Part A


Matter

Anything that has mass and occupies space

States of matter:

1. Soliddefinite shape and volume

2. Liquiddefinite volume, changeable shape

3. Gaschangeable shape and volume


Energy

Capacity to do work or put matter into motion

Types of energy:

Kineticenergy in action

Potentialstored (inactive) energy

PLAY Animation: Energy Concepts
http://energy_concepts.mov/http://energy_concepts.mov/


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Forms of Energy

Chemical energystored in bonds ofchemical substances

Electrical energyresults from movement ofcharged particles

Mechanical energydirectly involved inmoving matter

Radiant or electromagnetic energyexhibitswavelike properties (i.e., visible light,ultraviolet light, and X-rays)


Energy Form Conversions

Energy may be converted from one form toanother

Conversion is inefficient because someenergy is lost as heat


Composition of Matter

Elements

Cannot be broken down by ordinary chemical means

Each has unique properties:

Physical properties

Are detectable with our senses, or aremeasurable

Chemical properties

How atoms interact (bond) with one another


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Composition of Matter

Atoms

Unique building blocks for each element

Atomic symbol: one- or two-letter chemical

shorthand for each element


Major Elements of the Human Body

Oxygen (O)

Carbon (C)

Hydrogen (H)

Nitrogen (N)

About 96% of body mass


Lesser Elements of the Human Body

About 3.9% of body mass:

Calcium (Ca), phosphorus (P), potassium (K),sulfur (S), sodium (Na), chlorine (Cl),magnesium (Mg), iodine (I), and iron (Fe)


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Trace Elements of the Human Body

< 0.01% of body mass:

Part of enzymes, e.g., chromium (Cr),

manganese (Mn), and zinc (Zn)


Atomic Structure

Determined by numbers of subatomicparticles

Nucleus consists of neutrons and protons


Atomic Structure

Neutrons

No charge

Mass = 1 atomic mass unit (amu)

Protons

Positive charge

Mass = 1 amu


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Atomic Structure

Electrons

Orbit nucleus

Equal in number to protons in atom

Negative charge

1/2000 the mass of a proton (0 amu)


Models of the Atom

Orbital model: current model used bychemists

Depicts probable regions of greatest electrondensity (an electron cloud)

Useful for predicting chemical behavior ofatoms


Models of the Atom

Planetary modeloversimplified, outdated

model

Incorrectly depicts fixed circular electron paths

Useful for illustrations (as in the text)


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Copyright 2010 Pearson Education, Inc. Figure 2.1

(a) Planetary model (b) Orbital model

Helium atom

2 protons (p+)2 neutrons (n0)2 electrons (e)

Helium atom

2 protons (p+)2 neutrons (n0)2 electrons (e)

Nucleus Nucleus

Proton Neutron Electroncloud

Electron


Identifying Elements

Atoms of different elements contain differentnumbers of subatomic particles

Compare hydrogen, helium and lithium (nextslide)


Proton

Neutron

Electron

Helium (He)(2p+; 2n0; 2e)

Lithium (Li)(3p+; 4n0; 3e)

Hydrogen (H)(1p+; 0n0; 1e)


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Atomic number = number of protons innucleus



Mass number = mass of the protons andneutrons

Mass numbers of atoms of an element are notall identical

Isotopes are structural variations of elementsthat differ in the number of neutrons they

contain



Atomic weight = average of mass numbers of

all isotopes


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Proton

Neutron

Electron

Deuterium (2H)(1p+; 1n0; 1e)

Tritium (3H)(1p+; 2n0; 1e)

Hydrogen (1H)(1p+; 0n0; 1e)


Radioisotopes

Spontaneous decay (radioactivity)

Similar chemistry to stable isotopes

Can be detected with scanners


Radioisotopes

Valuable tools for biological research and

medicine

Cause damage to living tissue:

Useful against localized cancers

Radon from uranium decay causes lungcancer


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Molecules and Compounds

Most atoms combine chemically with otheratoms to form molecules and compounds

Moleculetwo or more atoms bondedtogether (e.g., H2 or C6H12O6)

Compoundtwo or more different kinds ofatoms bonded together (e.g., C6H12O6)


Mixtures

Most matter exists as mixtures

Two or more components physicallyintermixed

Three types of mixtures

Solutions

Colloids

Suspensions


Solutions

Homogeneous mixtures

Usually transparent, e.g., atmospheric air orseawater

Solvent

Present in greatest amount, usually a liquid

Solute(s)

Present in smaller amounts


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Concentration of Solutions

Expressed as

Percent, or parts per 100 parts

Milligrams per deciliter (mg/dl)

Molarity, or moles per liter (M)

1 mole = the atomic weight of an element ormolecular weight (sum of atomic weights) ofa compound in grams

1 mole of any substance contains 6.021023molecules (Avogadros number)


Colloids and Suspensions

Colloids (emulsions)

Heterogeneous translucent mixtures, e.g.,cytosol

Large solute particles that do not settle out

Undergo sol-gel transformations

Suspensions:

Heterogeneous mixtures, e.g., blood

Large visible solutes tend to settle out


Solution

Solute

particles

Solute

particlesSolute

particles

Solute particles are very

tiny, do not settle out or

scatter light.

Colloid

Solute particles are larger

than in a solution and scatter

light; do not settle out.

Suspension

Solute particles are very

large, settle out, and may

scatter light.

ExampleMineral water

ExampleGelatin

ExampleBlood


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Mixtures vs. Compounds

Mixtures

No chemical bonding between components

Can be separated physically, such as bystraining or filtering

Heterogeneous or homogeneous

Compounds

Can be separated only by breaking bonds

All are homogeneous


Chemical Bonds

Electrons occupy up to seven electron shells(energy levels) around nucleus

Octet rule: Except for the first shell which isfull with two electrons, atoms interact in a

manner to have eight electrons in theiroutermost energy level (valence shell)


Chemically Inert Elements

Stable and unreactive

Outermost energy level fully occupied orcontains eight electrons


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Copyright 2010 Pearson Education, Inc. Figure 2.5a

Helium (He)(2p+; 2n0; 2e)

Neon (Ne)(10p+; 10n0; 10e)

2e 2e8e

(a) Chemically inert elements

Outermost energy level (valence shell) complete


Chemically Reactive Elements

Outermost energy level not fully occupied byelectrons

Tend to gain, lose, or share electrons (formbonds) with other atoms to achieve stability

Copyright 2010 Pearson Education, Inc. Figure 2.5b

2e4e

2e8e

1e

(b) Chemically reactive elements

Outermost energy level (valence shell) incomplete

Hydrogen (H)(1p+; 0n0; 1e)

Carbon (C)(6p+; 6n0; 6e)

1e

Oxygen (O)(8p+; 8n0; 8e)

Sodium (Na)(11p+; 12n0; 11e)

2e6e


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Types of Chemical Bonds

Ionic

Covalent

Hydrogen


Ionic Bonds

Ions are formed by transfer of valence shellelectrons between atoms

Anions ( charge) have gained one or moreelectrons

Cations (+ charge) have lost one or moreelectrons

Attraction of opposite charges results in an

ionic bond

Copyright 2010 Pearson Education, Inc. Figure 2.6a-b

Sodium atom (Na)(11p+; 12n0; 11e)

Chlorine atom (Cl)(17p+; 18n0; 17e)

Sodium ion (Na+) Chloride ion (Cl)Sodium chloride (NaCl)

+

(a) Sodium gains stability by losing one electron, and

chlorine becomes stable by gaining one electron.

(b) After electron transfer, the oppositely

charged ions formed attract each other.


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Formation of an Ionic Bond

Ionic compounds form crystals instead ofindividual molecules

NaCl (sodium chloride)

Copyright 2010 Pearson Education, Inc. Figure 2.6c

CI

Na+

(c) Large numbers of Na+ and Cl ions

associate to form salt (NaCl) crystals.


Covalent Bonds

Formed by sharing of two or more valence

shell electrons

Allows each atom to fill its valence shell at

least part of the time


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+

Hydrogenatoms

Carbonatom

Molecule ofmethane gas (CH4)

Structuralformulashowssinglebonds.

(a) Formation of four single covalent bonds:

carbon shares four electron pairs with fourhydrogen atoms.

or

Resulting moleculesReacting atoms


or

Oxygenatom

Oxygenatom

Molecule ofoxygen gas (O2)

Structuralformulashowsdoublebond.(b) Formation of a double covalent bond: Two

oxygen atoms share two electron pairs.


+


+ or

Nitrogenatom

Nitrogenatom

Molecule ofnitrogen gas (N2)

Structuralformulashowstriplebond.(c) Formation of a triple covalent bond: Two

nitrogen atoms share three electron pairs.



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Covalent Bonds

Sharing of electrons may be equal or unequal

Equal sharing produces electrically balanced

nonpolar molecules

CO2



Covalent Bonds

Unequal sharing by atoms with different

electron-attracting abilities produces polarmolecules

H2O

Atoms with six or seven valence shellelectrons are electronegative, e.g., oxygen

Atoms with one or two valence shellelectrons are electropositive, e.g., sodium


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Hydrogen Bonds

Attractive force between electropositive

hydrogen of one molecule and anelectronegative atom of another molecule

Common between dipoles such as water

Also act as intramolecular bonds, holding alarge molecule in a three-dimensional shape

PLAY Animation: Hydrogen Bonds
http://hydrogen_bonds.mov/http://hydrogen_bonds.mov/


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(a) The slightly positive ends ( +) of the watermolecules become aligned with the slightly

negative ends ( ) of other water molecules.

+

+

+

+

+

+

Hydrogen bond(indicated bydotted line)

Figure 2.10a


(b) A water strider can walk on a pond because of the high

surface tension of water, a result of the combined

strength of its hydrogen bonds.


Chemical Reactions

Occur when chemical bonds are formed,

rearranged, or broken

Represented as chemical equations

Chemical equations contain:

Molecular formula for each reactant andproduct

Relative amounts of reactants and products,which should balance


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Examples of Chemical Equations

H + H H2 (hydrogen gas)

4H + C CH4 (methane)

(reactants) (product)


Patterns of Chemical Reactions

Synthesis (combination) reactions

Decomposition reactions

Exchange reactions


Synthesis Reactions

A + B AB

Always involve bond formation

Anabolic


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Example

Amino acids are joined together toform a protein molecule.

(a) Synthesis reactions

Smaller particles are bonded

together to form larger,more complex molecules.

Amino acidmolecules

Proteinmolecule


Decomposition Reactions

AB A + B

Reverse synthesis reactions

Involve breaking of bonds

Catabolic


Example

Glycogen is broken down to releaseglucose units.

Bonds are broken in larger

molecules, resulting in smaller,less complex molecules.

(b) Decomposition reactions

Glucosemolecules

Glycogen


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Exchange Reactions

AB + C AC + B

Also called displacement reactions

Bonds are both made and broken


Example

ATP transfers its terminal phosphategroup to glucose to form glucose-phosphate.

Bonds are both made and broken

(also called displacement reactions).

(c) Exchange reactions

Glucose Adenosine triphosphate (ATP)

Adenosine diphosphate (ADP)Glucosephosphate

+

+


Oxidation-Reduction (Redox) Reactions

Decomposition reactions: Reactions in which

fuel is broken down for energy

Also called exchange reactions because

electrons are exchanged or shared differently

Electron donors lose electrons and areoxidized

Electron acceptors receive electrons andbecome reduced


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Chemical Reactions

All chemical reactions are either exergonic orendergonic

Exergonic reactionsrelease energy

Catabolic reactions

Endergonic reactionsproducts contain more

potential energy than did reactants

Anabolic reactions


Chemical Reactions

All chemical reactions are theoretically reversible

A + B AB

AB A + B

Chemical equilibrium occurs if neither a forward norreverse reaction is dominant

Many biological reactions are essentially irreversibledue to

Energy requirements Removal of products


Rate of Chemical Reactions

Rate of reaction is influenced by:

temperature rate

particle size rate

concentration of reactant rate

Catalysts: rate without being chemicallychanged

Enzymes are biological catalysts

chapter 2 anatomy lect notes

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