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The Chemistry of Life

The Nature of Matter, Water,Carbon

Compounds, Chemical Reactions and Enzymes

The Nature of Matter B.1.9 Both living and nonliving things are

composed of compounds, which are themselves made up of elements joined by energy-containing bonds, such as those in ATP.

ATP- universal energy source for all cells found in all living things.

Atom- basic unit of matter.

Subatomic particles- protons, neutrons, and electrons.

Atoms • Protons are positively

charged, and neutrons are neutral in charge, and they both make up the nucleus of an atom.

• Protons and neutrons make up the mass of an atom.

Atoms • Electrons are negatively

charged particles that orbit around the nucleus.

• Electrons are attracted to the nucleus and are in constant motion.

• Atoms are neutral in charge because they have equal number of protons as electrons.

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Elements and Isotopes

• Element- a pure substance that

consists entirely of one type of

atom.

• More than 100 elements are

known, but only about two

dozen are commonly found in

organisms.

Elements and Isotopes

• Elements are represented as either one or two letters and are listed on the periodic table.

• Elements are listed on the periodic table by the number of protons/electrons that they have.

Symbols for Elements

• All elements are classified and arranged according to their chemical properties in

the periodic table of elements.

• The number of protons and neutrons in atoms of different elements varies widely.

• Atomic number is the number of protons in

an atoms nucleus.

• Atomic mass = # Protons + # Neutrons

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Carbon Atom

Electron Energy Levels Valence Electrons

• The electrons in the outermost energy level determine the chemical behavior of the different elements.

• The outermost electrons are called valence electrons

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Bell-Ringer

1. How many protons, neutrons, and

electrons does one atom of oxygen

have?

2. Draw a model of an oxygen atom.

Bell-Ringer

How many valence electrons does carbon have? Identifying Atoms

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Identifying Atoms Identifying Atoms

Identifying Atoms Valence Electrons

The electrons in the outermost energy level determine the chemical behavior of the different elements.

The outermost electrons are called valence electrons

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Isotopes

• Isotopes- atoms of an element that have different number of neutrons.

• Mass number- the sum of protons and neutrons in the nucleus of an atom.

• Isotopes have different mass numbers, but the same atomic number.

Isotopes

• Because they have the same number of electrons, all isotopes of an element have the same chemical properties.

• Radioactive isotopes- have unstable nuclei that break down at a constant rate over time, and are used for dating purposes, and tracers.

Isotopes of Carbon Ions • Recall that atoms are electrically neutral

because they have equal numbers of protons

and electrons.

• An atom that loses electrons becomes

positively charged (+)

• An atom that gains electrons becomes

negatively charged (-)

• Positively and negatively charged atoms are

called IONS

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Chemical Bonds

Atoms in compounds are held together by chemical bonds.

Bond formation involves the electrons that surround a nucleus.

Ions – atoms that lose or gain electrons

Ionic bond- is formed when one or more electrons are transferred from one atom to another (ex. NaCl).

Oppositely charged ions have a strong attraction, which is an ionic bond.

Chemical Bonds continued

Covalent bond- situation where elements share

electrons between them, instead of transferring them.

Electrons travel in orbits of both elements of a covalent bond.

Molecule- the smallest unit of most compounds

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Chemical Compounds

Most elements in nature are found combined with

other elements.

Compound- a substance formed by the chemical

combination of two or more elements in definite proportions.

Chemical formula- the composition of compounds in terms of types of elements, and numbers of

each.

The physical and chemical properties of a

compound are usually very different from those of

the elements from which it is formed.

Chemical Bonds continued

Van der Waals forces- a slight attraction

that develops between oppositely charged regions of nearby molecules.

They are weaker than both ionic and covalent bonds.

This is how geckos can defy gravity and climb walls that are smooth.

Properties of Water Water covers over 75% of the Earth’s

surface.

Water is the single most abundant

compound in most living things.

It is a liquid at most of Earth’s temperatures.

It expands when it freezes and is less dense

than liquid water.

It is neutral in charge, but polar.

Polarity- an uneven distribution of electrons.

Hydrogen Bonds

Not as strong as covalent or ionic bonding.

A hydrogen bond is found between the oxygen of one water molecule with the hydrogen of another.

Cohesion- an attraction between molecules of the same substance. (allows insects to walk on water)

Adhesion- an attraction between molecules of different substances.

Capillary action- one of the forces that draw water out of the roots of a plant and up into its stems and leaves.

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Properties of Water

Life can not exist without water.

Water is the universal solvent because it dissolves more substances than any other liquid.

Pure water is 7.0 on the pH scale (Neutral).

Water moves against the force of gravity due to capillary action.

It is the only natural substance that is found in three states of matter.

Water has a high surface tension and a high specific heat index.

Solutions and Suspensions

Mixtures- a material composed of two or more elements or compounds that are physically mixed together but not chemically combined.

Solution- a mixture in which one or more substances are uniformly distributed in another substance.

Suspension- mixtures of water and non-dissolved material. (ex. blood)

Solutions and Suspensions

Solute- part of solution that gets dissolved.

Solvent- substance that does the dissolving.

Solutions and Suspensions

Aqueous- solutions containing water for a solvent.

Concentration- the

measurement of the amount of solute dissolved in a fixed amount of solution.

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Acids and Bases

OH- hydroxide ion H+ hydrogen ion

acid- number of hydrogen ions is greater than

hydroxide ions. base- number of hydroxide ions is greater than

hydrogen ions

pH scale- measures the amount of hydroxide

and hydrogen ions that are present.

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Acids and Bases

(cont.)

Buffers- chemical substances that

neutralize small amounts of an

acid or a base of a solution.

There are different pH levels

throughout cells and the body.

Some molecules will be

destroyed if the pH is not right

B.1.5.

Acids and Bases

(cont.)

• Why are buffers important?

• Because they help maintain homeostasis

within an organism by keeping pH at a nearly

constant value.

• In humans, for example, a pH shift of only

about .4 units is fatal.

Determining pH of Solutions Determining pH of Solutions

• Procedures 1. Find an open lab station with a labeled solution

2. Take the pH of the solution by dipping a strip of

pH paper into the solution

3. Match the color of the pH paper with the guide

to approximate the pH.

4. Record the pH in your data table

5. Set the pH paper on the paper towel.

6. Repeat steps 1-5 with all solutions

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Determining pH of Solutions

• Cautions • Do not smell, taste, or touch the solutions

• Place the pH paper on the paper towel

when done.

• After you are done with the lab, wash

your hands

Carbon Atom

CARBON BONDING

Carbon has four electrons in the outer orbital.

(Valence Electrons)

Carbon forms four covalent bonds.

Carbon forms bonds with other elements as well

as with carbon (chains unlimited in length).

Carbon forms chains, branches, and rings. B.1.6

The Major Elements of Life

•Carbon, hydrogen,

oxygen, phosphorus,

sulfer, and nitrogen are the

most essential elements

for all living things

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Carbon Compounds

• Organic chemistry- compounds that contain bonds between carbon atoms.

• Macromolecules- giant molecules that are made from thousands or even hundreds of thousands of smaller molecules.

Carbon Compounds

• Polymerization- large compounds are built by joining smaller ones together.

• Monomers are smaller compounds that join together to make polymers.

• Monomers may be the same molecules repeated, or different ones.

Carbohydrates

• Carbohydrates- compounds made up of carbon, hydrogen, and oxygen atoms, usually in a ratio of 1:2:1.

• Used primarily by living things for energy.

• Plants and animals also use them for structural purposes. (ex. Cellulose makes up the cell walls of plants)

• Plants store energy as starch, and animals store it glycogen.

Carbohydrates cont.

• Sugars are the monomers and starches and

cellulose are the polymers.

• Single sugar molecules are called

monosaccharides, two sugars are disaccharides, and starches and cellulose are polysaccharides.

• Fructose, dextrose, glucose, galactose, ribose, sucrose, and maltose are examples of mono and

disaccharides.

• Starches contain hundreds of sugar monomers

and cellulose contain around three thousand.

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Lipids

Lipids are made mostly from carbon and hydrogen

atoms.

Common types are fats, oils, steroids, and waxes.

They are generally not soluble in water.

They are used primarily to store energy, insulation,

making cell membranes, and waterproofing.

The monomers are glycerols and fatty acids.

Saturated fats- have the maximum possible number of hydrogen atoms attached to carbon.

Lipids cont.

Unsaturated fats- have at least one carbon-carbon

double bond.

Polyunsaturated fats- have more than one carbon-

carbon double bond.

Lipids, like other molecules (ATP) have high energy

bonds. B.1.10

Unsaturated fats tend to be liquids at room

temperature.

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Nucleic Acids (DNA)

• Contain hydrogen, oxygen, nitrogen, carbon,

and phosphorus.

• Nucleotides are monomers of which there are

only four types found in DNA and RNA.

• Adenine

• Thymine

• Cytosine

• Guanine

Nucleic Acids (DNA)

• DNA and RNA are polymers of Nucleic

Acids.

• Nucleic acids store and transmit

heredity, or genetic information.

Proteins

• Contain nitrogen, carbon, oxygen, sulfur, and hydrogen.

• Amino acids are the monomers of protein.

• There are roughly 20 amino acids found in nature.

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Proteins • Amino acids have an amino group on one end

that joins with a carboxyl group of another.

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Proteins

• Some proteins control the rate of reactions and regulate cells processes. (ENZYMES)

• Others transport substances into or out of cells, or fight diseases, or build things.

• Examples include enzymes, hormones, hemoglobin and the cell wall.

20 Different Amino Acids

Each has:

-a carbon core atom

-an amine group NH3

-a carboxyl group COOH

-and an R-group, which

makes them all different

-a hydrogen atom

Chemical Reactions and

Enzymes

• Chemical reaction- a process that

changes one set of chemicals into

another set of chemicals.

• Reactants- elements or compounds

that enter a reaction.

• Products- elements or compounds

that are produced by a chemical

reaction.

Chemical Reactions and

Enzymes

• Some chemical reactions occur

slowly, while others are very sudden.

• Chemical reactions always involve

the breaking of bonds in reactants

and the formation of new bonds in

products.

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Energy in Reactions

• Energy is released or absorbed whenever chemical bonds form or are broken.

• Chemical reactions that release energy often occur spontaneously. (exothermic)

• Chemical reactions that absorb energy will not occur without a source of energy. (endothermic)

Energy in Reactions

• Activation energy- energy that is needed to get a reaction started.

• Activation energy is a factor in whether the overall chemical reaction releases energy or absorbs energy.

Enzymes

• Some chemical reactions are too slow, or the activation energy is too high to work in living systems.

• Catalyst- a substance that speeds up the rate of a chemical reaction.

• Enzyme- proteins that act as biological catalysts.

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Enzymes

• Enzymes speed up reactions that take place in cells by lowering activation energies.

• Enzymes are very specific in that they usually only do one job.

• Many different types of enzymes exist in organisms.

Enzyme Action

Enzymes provide a site so that reactants can be brought together to react.

Active site- location where reactants meet in an enzyme.

Substrates- the reactants that meet in the active site.

Emil Fisher proposed the “lock and key” method to describe how substrates fit into enzymes.

Once the reaction is over, the products are released and the enzyme remains unchanged, so that it can work on more substrate.

Enzymes are affected by pH, temperature, and amount of substrate.

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LOCK AND KEY MODEL Chapter 2 Review

• Describe the structure of an atom

• An atom of Calcium contains 20 protons,

how many electrons does it have?

• Why do all isotopes of an element have the same chemical properties?

• Compare the structure of Carbon-12 and Carbon-14

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Chapter 2 Review

• What is a compound?

• What are two types of bonds that

hold the atoms within a compound

together?

• A potassium ion loses one valence

electron, What type of bond will it form with a chlorine atom?

Chapter 2 Review

• What does it mean when a molecule

is said to be “polar”?

• Why is water such a good solvent?

• What is an acid?

• What is a base?

Chapter 2 Review

• What are the major elements of life?

• What are the 4 groups of organic

molecules (macromolecules)?

• What happens to chemical bonds

during a chemical reaction?

Chapter 2 Review

• Why is the melting of ice not a

chemical reaction?

• What is activation energy?

• What is a catalyst?

• What are enzymes?

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The Major Elements of Life

•Carbon, hydrogen,

oxygen, phosphorus,

sulfur, and nitrogen are

the most essential

elements for all living

things (CHOPSN)

The Organic Compounds of Life

(Macromolecules)

•Carbohydrates

•Lipids

•Protein

•Nucleic Acids

CHAPTER 2 REVIEW

• The positively charged particle in an atom is called the:

A. neutron B. ion C. proton

D. electron

CHAPTER 2 REVIEW

• The positively charged particle in an atom is called the:

A. neutron B. ion C. proton

D. electron

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CHAPTER 2 REVIEW

• Two or more different atoms are combined in definite proportions in any:

A. symbol B. isotope

C. element D. compound

CHAPTER 2 REVIEW

• Two or more different atoms are combined in definite proportions in any:

A. symbol B. isotope

C. element D. compound

CHAPTER 2 REVIEW

• A covalent bond is formed by the:

A. transfer of electrons

B. sharing of electrons C. gaining of electrons D. losing of electrons

CHAPTER 2 REVIEW

• A covalent bond is formed by the:

A. transfer of electrons

B. sharing of electrons C. gaining of electrons D. losing of electrons

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CHAPTER 2 REVIEW

• When you shake sugar and sand together in a test tube, you cause them to form a

A. compound B. mixture

C. solution D. suspension

CHAPTER 2 REVIEW

• When you shake sugar and sand together in a test tube, you cause them to form a

A. compound B. mixture

C. solution D. suspension

CHAPTER 2 REVIEW

• A compound that produces hydrogen ions in solution is a(n):

A. salt B. acid C. base

D. polymer

CHAPTER 2 REVIEW

• A compound that produces hydrogen ions in solution is a(n):

A. salt B. acid C. base

D. polymer

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CHAPTER 2 REVIEW

• Compared to most other substances,

a great deal of heat is needed to raise

the temperature of water by a given

amount. This is because water

A. is an acid B. readily forms solutions C. has a high heat capacity

D. acts as a buffer

CHAPTER 2 REVIEW

• Compared to most other substances,

a great deal of heat is needed to raise

the temperature of water by a given

amount. This is because water

A. is an acid B. readily forms solutions C. has a high heat capacity

D. acts as a buffer

CHAPTER 2 REVIEW

• The monomers of carbohydrates are called:

A. sugars B. nucleic acids C. nucleotides

D. amino acids

CHAPTER 2 REVIEW

• The monomers of carbohydrates are called:

A. sugars B. nucleic acids C. nucleotides

D. amino acids

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CHAPTER 2 REVIEW

• Proteins are polymers formed from:

A. lipids B. carbohydrates C. amino acids

D. nucleic acids

CHAPTER 2 REVIEW

• Proteins are polymers formed from:

A. lipids B. carbohydrates C. amino acids

D. nucleic acids

CHAPTER 2 REVIEW

• An enzyme speeds up the rate of reaction by:

A. lowering the activation energy B. raising the activation energy C. releasing energy

D. absorbing energy

CHAPTER 2 REVIEW

• An enzyme speeds up the rate of reaction by:

A. lowering the activation energy B. raising the activation energy C. releasing energy

D. absorbing energy

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CHAPTER 2 REVIEW

• In a chemical reaction, a reactant binds to an enzyme in a region known as the:

A. catalyst B. product

C. substrate D. active site

CHAPTER 2 REVIEW

• In a chemical reaction, a reactant binds to an enzyme in a region known as the:

A. catalyst B. product

C. substrate D. active site