chemistry - spring 2013 (student copy)

8/22/2019 Chemistry - Spring 2013 (Student Copy)

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Copyright 2010 Pearson Education, Inc.

Chemistry

Chapter 2


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Q&A

A Salmonella bacteriumreleases a regulatory

molecule containing amino

acids and phosphate that

causes a human cellscytoskeleton to change

shape, thereby allowing

the bacterium to enter the

cell. What type of chemical

is this regulatory molecule?


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Learning Objectives

The Structure of Atoms

2-1 Describe the structure of an atom and its relation

to the physical properties of elements.


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Chemistry is the study of interactions betweenatoms and molecules

The atom is the smallest unit of matter that enters

into chemical reactions

Atoms interact to form molecules


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Atoms are composed of

ProtonsPositive charge

Located in nucleus

1 atomic unit

Neutrons

No charge

Located in nucleus

1 atomic unit Electrons

Negative charge

Orbit nucleus

No significant weight


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Copyright 2010 Pearson Education, Inc. Figure 2.1


Protons and neutrons are in the nucleus

Electrons move around the nucleusElectron shell


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O

8

16 O

8

17 O

8

18

Chemical Elements

Atomic number: # Protons in Atom

Atomic weight: Sum of Protons and Neutrons in Atom

Atomic symbol: Letter(s) representing each element

Isotopes of an element are atoms with different

numbers of neutrons. Isotopes of oxygen:



Chemical Elements

Atom can:

Gain/Lose Electrons

Lose Excess Neutrons

Never Gain/Lose Protons


9/101Copyright 2010 Pearson Education, Inc.Table 2.1

The Elements of Life



Electronic Configurations

Electrons are arranged in electron shellscorresponding to different energy levels



Check Your Understanding How does C differ from C? What is the atomic

number of each carbon atom?

The atomic weight? 2-1

14

6

12

6



Learning Objectives2-2 Define ionic bond, covalent bond, hydrogen bond,

molecular weight, and mole.

How Atoms Form Molecules



How Atoms Form Molecules

Atoms combine to complete the outermost shell

Valence: Number of missing or extra electrons inthe outermost shell

The # electrons in the valence affects the behavior

of the atom The atom is stable when the valence is full

The atom is unstable/reactive when the valence is

incomplete



Chemical Bonds

Join atoms by valence electrons

Atoms tend to Gain, Lose, orShare electrons to fill

their valence

Types of chemical bonds:

Ionic

Covalent

Hydrogen



Ionic Bonds

Transferof electrons from one atom to another

Atoms that gain electrons have net negative charge

Atoms that lose electrons have net positive charge

Ion: Atom with a net charge

Ionic Bond: Attraction between oppositely charged

ions.


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Copyright 2010 Pearson Education, Inc. Figure 2.2a

Ionic Bonds


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Ionic Bonds

Atoms with 1-3 valence electrons tend to lose them

Atoms with 5-7 valence electrons tend to gain

additional electrons

Ionic bonds common in inorganic molecules

Ionically formed compounds dissolve easily in water

electrolytes


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Copyright 2010 Pearson Education, Inc. Figure 2.2b

Ionic Bonds


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Covalent Bonds

Covalent bonds form when two atoms share one ormore pairs of electrons


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Covalent Bonds

Carbon may form up to 4 covalent bonds


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Covalent Bonds

Carbon may share up to 3 pairs of electrons withanother atom


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Hydrogen Bonds

Weak attraction between slightlypositive hydrogen atom and

slightly negative atom (O, N)


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Hydrogen Bonds

May form within same molecule or

between molecules Easily broken by temperature or pH

Common between H2O molecules,

amino acids, nucleic acids

Results in 3-D shape of proteins


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Hydrogen Bonds

Why is ice less dense

than liquid water?


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Hydrogen Bonds

What causes capillary

action to occur in thesetubes?

Why does the water

travel higher in the

thinner tube?


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Chemical Bonds Review


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H2O

2H = 2 1 = 2

O = 16

MW = 18

1 mole weighs 18g

Molecular Weight and Moles

The sum of the atomicweights in a molecule is

the molecular weight

One mole of a substance

is its molecular weight ingrams


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Check Your Understanding Differentiate an ionic bond from a covalent bond. 2-

2


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Learning Objectives

Chemical Reactions

2-3 Diagram three basic types of chemical reactions.


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Chemical Reactions

Chemical reactions involve the making or breakingof bonds between atoms

A change in chemical energy occurs during a

chemical reaction

Endergonic reactions absorb energy

Exergonic reactions release energy


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Anabolism is the synthesis of molecules in a cell

A + B ABAtom, ion,or molecule A

Atom, ion,or molecule B

New molecule

AB

Combines

to form

Synthesis Reactions


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Catabolism is the decomposition reactions in a cell

A + BABAtom, ion,

or molecule A

Atom, ion,

or molecule B

New molecule

AB

Breaks

down into

Decomposition Reactions


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NaCl + H2ONaOH + HCl

Exchange Reactions


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A + BWater

AB

Heat

Reversible Reactions

Can readily go in either direction

Each direction may need special conditions

R d R ti


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Redox Reactions

Coupled Oxidation/Reduction Reactions

Oxidation releases electrons

Reduction causes atom to receive electrons

Essential to biochemical processes


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Check Your Understanding

HClO + Na2SO3Na2SO4 + HCl

This chemical reaction below is used to removechlorine from water.

What type of reaction is it? 2-3

I t t Bi l i l M l l


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Important Biological Molecules

Organic compounds always contain carbon andhydrogen

Inorganic compounds typically lack carbon

I i C d


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Learning Objectives

Inorganic Compounds

2-4 List several properties of water that are important

to living systems.

2-5 Define acid, base, salt, andpH.

W t


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Water

Inorganic

Polar, Solvent

Temperature buffer

2/3 by weight (human)

W t


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Water

W t


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RR + H2O ROH + HR

Maltose + H2O Glucose + Glucose

Water

H+ and OH

participate in chemical reactions

W t


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Maltose + H2O Glucose + Glucose

Glucose C6H12O6

Glucose +C6H12O6

Total C12H24O12

Maltose C12H22O11

The difference is:

Water

W t


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Water

H bonds absorb heat

A id B d S lt


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Acids, Bases, and Salts

Acids


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Acids

Substances that releaseH+ in solution

pH < 7

HCl H+ + Cl

Bases


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Bases

Substances that releaseOH in solution

pH > 7

NaOH Na+ + OH

Salts


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Copyright 2010 Pearson Education, Inc.Figure 2.6c

Salts

Ionic compounds

Dissociate in H2O

Dont release H+ or OH

Act as electrolytes

NaCl Na+ + Cl

pH


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pH

Power of hydrogen

Scale to indicate relative [H+] and [OH]

pH = log[H+]

0 14

7 is neutral (water)

Most organisms grow best between pH 6.5 and 8.5

The pH Scale


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The pH Scale


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Mg(OH)2 + 2HCl MgCl2 +H2O

Why is the polarity of a water molecule important?

2-4

Antacids neutralize acid by the following reaction.

Identify the acid, base, and salt. 2-5

Organic Compounds


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Learning Objectives

Organic Compounds

2-6 Distinguish organic and inorganic compounds.

2-7 Define functional group.

Structure and Chemistry


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The chain of carbon atoms in an organic molecule is

the carbon skeleton



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Functional groups are responsible for most of the

chemical properties of a particular organic

compound.

Functional Groups


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Copyright 2010 Pearson Education, Inc. Table 2.3

Functional Groups

Functional Groups


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Copyright 2010 Pearson Education, Inc. Table 2.3

Functional Groups

Functional Groups


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Functional Groups

Identify the functional groups in an amino acid:


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Define organic. 2-6

Add the appropriate functional group(s) to the ethyl

group below to produce each of the following

compounds: ethanol, acetic acid, acetaldehyde,ethanolamine, diethyl ether. 2-7

Organic Compounds


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Learning Objectives

Organic Compounds

2-8 Identify the building blocks of carbohydrates.

2-9 Differentiate simple lipids, complex lipids, and

steroids.

2-10 Identify the building blocks and structure of

proteins.

2-11 Identify the building blocks of nucleic acids.

2-12 Describe the role of ATP in cellular activities.

Organic Compounds


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Organic Compounds

Small organic molecules can combine into large

macromolecules

Macromolecules are polymers consisting of many

small repeating molecules

The smaller molecules are called monomers

Polymers


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Monomers join by dehydration synthesis or

condensation reactions

Polymers

O

Chemical Reaction Terminology Review


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Chemical Reaction Terminology Review

DecompositionSynthesis

Match the following terms under Synthesis or

Decomposition.- Endergonic - Catabolism

- Hydrolysis - Anabolism

- Exergonic - Dehydration (Condensation)

Carbohydrates


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Carbohydrates

Cell structures and primary energy source

Consist of C, H, and O with the formula (CH2O)n

Monosaccharides are simple sugars with 3 to 7

carbon atoms

Carbohydrates


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Carbohydrates

Disaccharides are formed when 2

monosaccharides are joined in a dehydration

synthesis

Disaccharides can be broken down by hydrolysis

Dehydration Synthesis and Hydrololysis


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Dehydration Synthesis and Hydrololysis

Carbohydrates


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Carbohydrates

Oligosaccharides consist of 2 to 20

monosaccharides

Polysaccharides consist of tens or hundreds of

monosaccharides joined through dehydration

synthesis


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Give an example of a monosaccharide, a

disaccharide, and a polysaccharide. 2-8

Lipids


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Lipids

Essential components of cell membranes

Consist of C, H, and O

Are nonpolar and insoluble in water

Simple Lipids


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Simple Lipids

Fats ortriglycerides

Contain glycerol and 3 fatty acids; formed by

dehydration synthesis

Structural Formulas of Simple Lipids


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Copyright 2010 Pearson Education, Inc. Figure 2.9c

Structural Formulas of Simple Lipids

Simple Lipids


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Simple Lipids

Saturated (with hydrogen) - No double bonds

Unsaturated fat: One or more double bonds in thefatty acids

Cis vs. Trans Fatty Acids


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Cis vs. Trans Fatty Acids

c is: H atomson the same

side of the

double bond

t rans : H atoms

on opposite

sides of the

double bond

Complex Lipids


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Co p e p ds

Contain C, H, and O + P,

N, or S

Membranes are made of

phospholipids

Complex Lipids


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p p

Steroids


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Copyright 2010 Pearson Education, Inc.Figure 2.11

4 carbon rings with anOH group attached to one

ring


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How do simple lipids differ from complex lipids? 2-9

Proteins


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Consist of C, H, O, and N

Amino Acids (AAs)

Joined by peptide bond into chain = polypeptide

Structural (peptidoglycan) or regulatory (enzyme)

Complex, 3-D shape

Amino Acids


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Proteins consist of subunits called amino acids

Amino Acids


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Exist in either of two stereoisomers:

D orL.

L-forms are most often found in nature.

Amino Acids


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When growing in an

animal, Bacillusanthracis produces a

capsule that is

resistant to

phagocytosis. The

capsule is composed

of D-glutamic acid.Why is this capsule

resistant to digestion

by the host's

phagocytes?

Peptide Bonds


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p

Peptide bonds between amino acids are formed by

dehydration synthesis

Levels of Protein Structure


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Primary structure:



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Secondary structure:



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Tertiary structure: irregular folding due to bonding

between AAs in the polypeptide chain

disulfide bonds

hydrogen bonds

ionic bonds



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Copyright 2010 Pearson Education, Inc. Figure 2.15c



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Copyright 2010 Pearson Education, Inc. Figure 2.15d

Quaternary structure:

Protein Structure - Review


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Conjugated proteins consist of amino acids and

other organic molecules

Glycoproteins

Nucleoproteins

Lipoproteins

Q&A


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A Salmonella bacterium

releases a regulatory

molecule containing

amino acids and

phosphate that causesa human cells

cytoskeleton to change

shape, thereby allowing

the bacterium to enterthe cell. What type of

chemical is this

regulatory molecule?


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What two functional groups are in all amino acids?

2-10

Nucleic Acids


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Consist ofnucleotides

1) Pentose (5-C sugar: deoxyribose or ribose)

2) Phosphate group

3) Nitrogenous base (purine or pyrimidine)

DNA, RNA, ATP Acidic, found in nucleus

Sugar-phosphate backbone + bases as rungs of

ladder

Nucleic Acids


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Nitrogenous Bases:

DNA


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Deoxyribonucleic acid

Has deoxyribose

Exists as a double helix

A hydrogen bonds with T

G hydrogen bonds with C

DNA


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RNA


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Ribonucleic acid

Has ribose

Is single-stranded

A hydrogen bonds with U

C hydrogen bonds with G

DNA vs. RNA


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RNA DNA

Deoxyribose

A-T, C-G

Double stranded

Codes for proteins

Nucleus

ATP


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Adenosine triphosphate

Ribose Adenine

3 phosphate groups

The Structure of ATP


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ATP


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Is made by dehydration synthesis

Is broken by hydrolysis to liberate useful energy

for the cell


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Which can provide more energy for a cell and why:

ATP or ADP? 2-12

chemistry - spring 2013 (student copy)

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