ii.matter and energy a.principles of chemistryprinciples of chemistry b.waterwater c.organic...

II. Matter and Energy

A. Principles of chemistryB. WaterC. Organic compoundsD. Energy

II. Matter & Energy A. Principles of Chemistry B. Water C. Organic Compounds D. Energy

A. Principles of Chemistry

1. Atomic structure2. The periodic table3. Chemical bonding4. Important elements in environmental processe

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II. Matter & Energy A. Principles of Chemistry 1. Atomic structure 2. The periodic table 3. Chemical bonding 4. Important elements B. Water C. Organic Compounds D. Energy

A.1. Atomic Structure

Matter– Anything that takes up space and has mass

Atom– The smallest stable particle of matter– Composed of protons, neutrons, and electrons– Overall structure: textbook figure 2.3



Protons– Positively charged– Atomic mass 1 atomic mass unit– Located in the nucleus of an atom

Neutrons– Electrically neutral– Atomic mass 1 atomic mass unit– Located in the nucleus of an atom



Electrons– Negatively charged– Atomic mass: very small, almost negligible– Located in electron shells (orbitals) around the

nucleusIn a neutral atom, the number of electrons and protons is the sameAtoms can lose or gain electrons during chemical bonding



Element– A substance composed of only a single type of atom– Atomic number of an element

• The number of protons in its atoms• The atomic number is the same for all atoms of an

element– Mass number of an element

• The number of protons plus the number of neutrons in its atoms

• The atoms of an element may have a variable number of neutrons



Isotopes of an element– Different forms of an element with the same atomic

number but with different mass numbers– The atoms of some isotopes are stable– Other isotopes are radioactive, having unstable

atoms that spontaneously break apart (decay) to form other atoms

– When radioactive atoms decay, energy is released



For example, carbon has three isotopes– Carbon-12, with 6 protons and 6 neutrons, is the

most common form of carbon– Carbon-13, with 6 protons and 7 neutrons,

is stable (non-radioactive) and rare– Carbon-14, with 6 protons and 8 neutrons,

is unstable (radioactive) and rare


A.2. The Periodic Table

Textbook: figure 2.2 In the periodic table– Elements are listed in order of their atomic numbers– Elements are designated by standard one or two-

letter abbreviations– Elements in the same vertical column often have

very similar chemical bonding properties


A.2. The Periodic Table

Notable groups in the periodic table– Metals, nonmetals, and “metalloids”– Halogens– Nobel gases– Heavy metals– Synthetic elements (larger than uranium)


A.3. Chemical Bonding

Chemical bonding occurs when two or more atoms combineAtoms combine by exchanging or sharing electrons in their outermost electron shellChemical compound– Formed when the atoms of two or more different elements

combine by chemical bonding– Properties of a compound are usually very different than

those of its elements



Ionic bonds– Formed when electrons are completely transferred

from one atom to another– The atom that gains electrons becomes a negative ion

(anion)– The atom that loses electrons becomes a positive ion

(cation)– Example: Sodium chloride

Na + Cl Na+ Cl–



Covalent bonds– Form when two atoms share one or more pairs of

electrons– Molecule: consists of two or more atoms that are

joined by covalent bonding– Covalent bonds are generally more stable than ionic

bonds in aqueous (water) solution– Examples: textbook, figures 2.4 & 2.6


A.4. Important Elements

Textbook, table 2.1


B. Water

1. Structure of water2. Ionization of water3. Solvent properties of water4. Thermal properties of water

II. Matter & Energy A. Principles of Chemistry B. Water 1. Structure of Water 2. Ionization of Water 3. Solvent Properties 4. Thermal Properties C. Organic Compounds D. Energy

B.1. Structure of Water

A water molecule is composed of two hydrogen atoms covalently bonded to an oxygen atomThe hydrogen atoms form an angle of about 110°, so the molecule is “bent”



The oxygen nucleus exerts a greater “pull” on the electrons in the covalent bonds– Therefore, the oxygen atom has a partial negative

charge– And the hydrogen atoms have partial positive

charges


Because opposite charges attract each other, water molecules are attracted to each other and to other charged molecules or ions



The bent geometry of water and the attraction between water molecules gives rise to unique properties that are essential for its role in living organisms and the environment



B.2. Ionization of Water

Consider a glass of pure water:– In a tiny fraction of the water molecules

(1 out of 10 million), one of the hydrogen nuclei is completely pulled off the molecule

– This forms two ions:• A hydrogen ion (H+)• And a hydroxyl ion (OH–)

– This is caused by the attraction of the water molecules for each other


Water molecules are continuously splitting into ions and rejoining to form water molecules



In chemically pure water, the number of H+ and OH– ions are the sameCertain chemical substances, when dissolved in water, can change the amounts of H+ or OH–



Acid– A substance that increases the amount of H+

(and decreases the amount of OH–)

Base (Alkaline)– A substance that increases the amount of OH–

(and decreases the amount of H+)

Neutral substance– A substance that does not change the amounts of

H+ and OH– (so H+ remains equal to OH–)



Acidity and alkalinity are represented by a value called “pH”– Acids: pH value is less than 7– Bases: pH value is greater than 7– Neutral substances: pH value is equal to 7– Each pH value represents a 10-fold change in the

amount of H+ in the solution– So a substance with pH = 5 has a 10 times greater

amount of H+ than a substance with pH = 6– Textbook, figure 2.5



B.3. Solvent Properties of Water

Solution– A mixture of two (or more) different substances in

which the particles of one substance are completely interspersed with the particles of the other substance(s)

– Solvent: The substance that is present in the largest amount

– Solute: The substance(s) that are present in smaller amounts


Hydrophilic substances– Substances that can be dissolved in water– Water molecules are attracted to ions or to other

molecules that have partial positive and negative charges

– Examples of hydrophilic substances:• Sodium chloride (table salt): This substance consists of

sodium ions and chloride ions• Sucrose (table sugar): This substance is a compound with

many -OH groups in its structure, with many partial positive and negative charges



Hydrophobic substances– Substances that cannot be dissolved in water– Water molecules have difficulty interacting with

uncharged molecules. These substances tend to separate from water.

– Example of a hydrophobic substance:• Cooking oil: The molecules of cooking oil have long

chains of carbon atoms bonded to hydrogen. The atoms do not have the “bent” geometry of water, so there are no partial charges to attract the water.Therefore, oil and water don’t mix!



Amphipathic substances– Substances in which part of the molecule is

hydrophobic, and part of the molecule is hydrophilic– When amphipathic substances are mixed in water,

its molecules form into clusters called “micelles” • with the hydrophilic part on the outside of the micelle in

contact with water• and the hydrophobic part on the inside of the micelle,

away from the water .



Amphipathic substances (cont.)– Example of an amphipathic substance:

• Soap: Soap molecules have an ionic group attached to one end, and an oily hydrocarbon chain attached to the other end. When soap is mixed with water, it forms micelles that trap oily dirt molecules.



B.4. Thermal Properties of Water

Molecules are in constant motion due to the heat energy (kinetic energy) they containPhases of matter:– Solid

• Limited movement of molecules; non-fluid– Liquid

• Molecules can move freely around each other; fluid– Gas

• Molecules have greatest freedom of movement; substance can expand to fill the available space


Water has unusual thermal properties because of the attraction of water molecules for each other– Water has relatively high melting and boiling points– Water remains in a liquid state over a wide

temperature range– Water has a high heat capacity: it can absorb a large

amount of heat with a small change in temperature– The solid form of water (ice) is less dense than the

liquid, so ice floats on water

B.4. Thermal Properties of Water


C. Organic Compounds

1. Bonding of carbon2. Monomers and polymers3. Bioorganic compounds

II. Matter & Energy A. Principles of Chemistry B. Water C. Organic Compounds 1. Bonding of Carbon 2. Monomers & Polymers 3. Bioorganic compounds D. Energy

C. 1. Bonding of Carbon

Carbon can form four covalent bonds with other atoms, such as nitrogen, oxygen, phosphorus, sulfur, halogens, and other carbonsCompounds formed from the covalent bonding of carbon are called organic compoundsCarbon-carbon bonds are very stable, allowing the formation of very large organic molecules


Hydrocarbons– Consist of carbon and hydrogen– Usually hydrophobic– Aromatic hydrocarbons contain one or more

benzene rings (phenyl groups)

C. 1. Bonding of Carbon


C. 2. Monomers and Polymers

Monomer– An organic molecule that serves as a “building block”

to build larger organic molecules

Polymer– An organic molecule composed of two or more

monomer units linked together by covalent bonds


Condensation reaction– Polymers are often formed by the process of

condensation– In this process, two hydrogen atoms and an oxygen

atom are removed from two monomer units– And a covalent bond forms between the monomers

II. Matter & Energy A. Principles of Chemistry B. Water C. Organic Compounds 1. Bonding of Carbon 2. Monomers & Polymers 3. Bioorganic compounds D. Energy C. 2. Monomers and Polymers

Hydrolysis reaction– Polymers are often broken down by the process of

hydrolysis– In this process, a water molecule is inserted between

the monomer units of a polymer– To split the polymer into its monomer units


C. 3. Bioorganic Compounds

Textbook, figure 2.6 & table 2.2Carbohydrates– Composed mostly of carbon, hydrogen, and oxygen– Large number of –OH groups attached to the

carbons– Functions

• Energy source for living cells• Certain structural components of cells


Carbohydrates (cont.)– Monosaccharides

• “Simple sugars”• Monomer unit of carbohydrate group• Examples: Glucose, fructose

– Disaccharides• Composed of two monosaccharide units joined together• Examples: Sucrose, lactose

– Polysaccharides• Composed of multiple monosaccharide units (100s –

1000s)• Examples: Starch, glycogen, cellulose

II. Matter & Energy A. Principles of Chemistry B. Water C. Organic Compounds 1. Bonding of Carbon 2. Monomers & Polymers 3. Bioorganic compounds D. Energy C. 3. Bioorganic Compounds

Lipids– Biological compounds with hydrophobic components

in their molecular structures– Functions

• Energy storage• Structural components

– Glycerides• A major class of lipid• Composed of a glycerol molecule attached to one, two, or

three fatty acid molecules


Lipids (cont.)– Generalized structure of a triglyceride:


Proteins– Composed of chains of amino acids– There are 20 different amino acids, each with

distinctive chemical properties– A protein molecule may contain several hundred

amino acids– Each different protein has its own order, or

“sequence,” of amino acids– The correct sequence of amino acids is essential for

the protein’s function


Proteins (cont.)– Functions

• Enzymes: Enzymes are biological catalysts that control almost every reaction in living systems

• Cellular recognition and communication• Structural components of living cells


Nucleic acids– Composed of chains of nucleotides– There are 4 different nucleotides– A nucleic acid molecule may contain several

thousands or millions of nucleotides– Each nucleic acid molecule has its own order, or

“sequence,” of nucleotides– The correct sequence of nucleotides is essential for

the nucleic acid’s function


Nucleic acids (cont.)– Overall function

• The sequence of nucleotides in a nucleic acid molecule serves as a blueprint to encode the correct sequence of amino acids for a protein. The code for a specific protein is called a “gene.”

• Deoxyribonucleic acid (DNA): DNA molecules (chromosomes) serve as the “master blueprint” for all of the cell’s proteins. The DNA molecules are transmitted to offspring during reproduction.

• Ribonucleic acid (RNA): RNA molecules serve as “working copies” of the genes for the proteins that the cell is making at any given time.


D. Energy

1. Types of energy2. Oxidation and reduction3. Electrical generation

II. Matter & Energy A. Principles of Chemistry B. Water C. Organic Compounds D. Energy 1. Types of energy 2. Oxidation and reduction 3. Electrical generation

D. 1. Types of Energy

Energy– The ability to do work– The capacity to change matter

Kinetic energy and potential energy– Kinetic energy

• Energy associated with movement• Energy released as a process occurs

– Potential energy• “Stored” energy that is contained in matter• The potential of matter for undergoing change



Heat– Energy associated with the movement of molecules

Electromagnetism– Energy associated with electrical charges and

magnetic fields– Electric current is produced by electrons flowing

through a conductor (such as a copper wire)



Electromagnetic radiation– Energy that travels through space in the form of

“packets” of energy waves called photons– The amount of energy in a photon is related to its

wavelength: the shorter the wavelength, the more energy the photon has

– Photons can interact with matter to cause different affects, depending on the energy of the photons

– Textbook, figure 2.9


Chemical energy– Energy associated with the making or breaking of

chemical bonds– Exothermic reaction

• A chemical reaction in which energy is released– Endothermic reaction

• A chemical reaction in which energy is absorbed

Atomic energy– Energy released when radioactive isotopes split

apart (atomic fission) or fuse together (atomic fusion)– Textbook, figure 12.9



D. 2. Oxidation and Reduction

Energy is associated with the gain or loss of electrons by atoms in chemical reactionsReduction reaction– A reaction in which an atom gains electrons– By becoming bonded to a less electronegative atom

(such as hydrogen)– Compounds with more reduced atoms often have a

larger amount of potential chemical energy (in an oxygen atmosphere)



Oxidation reaction– A reaction in which an atom loses electrons– By becoming bonded to a more electronegative atom

(such as oxygen)– Compounds with more oxidized atoms often have a

smaller amount of potential chemical energy (in an oxygen atmosphere)

Oxidation and reduction reactions always occur together: one substance is oxidized, and another substance is reduced.



Examples:– Oxidation of methane (natural gas)2 CH4 + 4 O2 2 CO2 + 4 H2O + Energy (Heat & Light)

– Reduction of CO2 to form glucose in photosynthesis

6 CO2 + 6 H2O + Energy (Light) C6H12O6 + 6 O2


D. 3. Electrical Generation

Electric current– The movement of electrons through a conductor

(such as a copper wire)

Electrical generator– When a conductor (such as a copper wire) is moved

in a magnetic field, a current is generated in the wire– By moving a coil of wire within a strong magnetic

field, large electrical currents can be generated



Types of generators– Coal, oil, and natural gas generators

• Pressurized steam is generated by boiling water, using fossil fuels as an energy source

• The steam pressure is used to run turbines that are attached to the generator coils

– Hydroelectric generators• The energy from falling water (from waterfalls or dams) is

used to run turbines that are attached to generator coils



Types of generators (cont.)– Nuclear generators

• The tremendous heat from a nuclear chain reaction is used to generate pressurized steam

• The steam pressure is used to run a turbine that is attached to the generator coils

• Textbook, figures 12.9 & 12.11– Other methods

• Windmill generators• Tidal power generators (Figure 12.30)



Other methods of generating electricity– Chemical cells (“batteries”)

• Uses chemical oxidation and reduction• Often, the cells contain substance (such as heavy metals)

that are difficult to dispose • Figure 12.23

– Photovoltaic cells• Crystals of certain substances produce an electrical

current when exposed to light• Figure 12.20


ii.matter and energy a.principles of chemistryprinciples of chemistry b.waterwater c.organic...

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