4 Organic Compounds

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CHAPTER 3 Chemical Compounds SECTION 4 Organic Compounds

National Science BEFORE YOU READ Education Standards After you read this section, you should be able to answer PS 1a, 1b, 1c these questions: • Why are there so many organic compounds? • What are the names and the properties of organic compounds? • What organic compounds are found in living things?

How Does Carbon Form Compounds? Most of the chemical compounds that exist contain STUDY TIP carbon. These compounds are called organic compounds. Brainstorm With a partner, Organic compounds are compounds made of molecules write down the names of several of your favorite foods. in which carbon atoms are covalently bonded to other After you have read about atoms. the carbohydrates, lipids, and Every organic compound contains carbon. Carbon proteins, identify which of atoms have four outer electrons. This means that each these groups are in the foods. carbon atom can make four covalent bonds with other atoms. Most organic molecules have two or more carbon atoms linked to one another. READING CHECK The illustrations in the figure below are models of 1. Identify What do most organic molecules. These models are called structural organic molecules have in formulas. They show the order in which atoms in a mol- them? ecule are connected to one another. A line between two element symbols represents a covalent bond, or one pair of shared electrons. Models of Organic Molecules

H H H C H H C H H H H C H H H H C H H C H C H H C C H H C C H H C H H C C H H C H H C H C H H H TAKE A LOOK H C H H H H C H H 2. Identify What are three H ways carbon atoms link Straight chain Branched chain Ring together in organic molecules? Carbon atoms are con- The chain of carbon atoms The chain of carbon nected one after another. branches when a carbon atom atoms forms a ring. bonds to more than two other carbon atoms.

Notice that these molecules have chains of carbon atoms linked to one another. Some organic molecules have hundreds or thousands of carbon atoms linked together to form a backbone of the molecule.

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What Are Some Kinds of Organic Compounds? Many organic compounds contain atoms of several elements. The simplest organic compounds only contain two elements—carbon and hydrogen. Organic compounds that contain only carbon and hydrogen are called hydrocarbons. Hydrocarbons are grouped based on the covalent bonds between the carbon atoms, as shown in READING CHECK the figure below. 3. Describe What are Three Types of Bonds Between Carbon Atoms hydrocarbons? Single Bond Double Bond Triple Bond

H H H H H HCC C H C C HC C H H H HH H

The propane in a Fruits make ethene, Ethyne is better known TAKE A LOOK camping stove contains which is a compound as acetylene. It is burned 4. Identify What are three only single bonds. that helps ripen the fruit. in miners’ lamps and in types of hydrocarbons? welding torches. In some hydrocarbon molecules, each carbon atom shares one pair of electrons with each of four other atoms. This type of chemical bond is called a single bond. A hydrocarbon that has only single bonds is called a saturated hydrocarbon. It is also called an alkane. In an unsaturated hydrocarbon, at least one pair of carbon atoms shares more than one pair of electrons. A double bond is a covalent bond with two pairs of shared electrons. A triple bond has three pairs of shared electrons. When unsaturated organic molecules react, part of the double or triple bond can be broken. Other atoms can READING CHECK then be added to the molecule. 5. Describe How do saturated Hydrocarbons that contain a double bond are called and unsaturated hydrocarbons alkenes. Hydrocarbons that contain triple bonds are differ? called alkynes. Alkenes and alkynes are unsaturated hydrocarbons. Benzene is a compound that has six carbon atoms in a ring shape. It is found in most of the compounds that are called aromatic compounds. In addition to hydrocarbons, there are many other kinds of organic compounds. These compounds are made by adding atoms of other elements to hydrocarbons. The other elements include the halogens, oxygen, sulfur, and nitrogen.

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What Organic Chemicals Are Important to Life? STANDARDS CHECK Organic chemicals that are made by living things PS 1c Chemical elements do not break down during normal are called biochemicals. There are four important groups laboratory reactions involving such of biochemicals: carbohydrates, lipids, proteins, and treatments as heating, exposure to electric current, or reactions with nucleic acids. acids. There are more than 100 known elements that combine in a multitude of ways to produce CARBOHYDRATES compounds, which account for Carbohydrates are biochemicals that are made of the living and nonliving substances that we encounter. one or more simple sugar molecules. Living things use carbohydrates as an energy source. There are two types: Word Help: chemical of or having to do with the simple carbohydrates and complex carbohydrates. The properties or actions of figure below shows how atoms and molecules form car- substances bohydrates. Word Help: involve to have as a part of Glucose Cellulose Glycogen CH2OH 6. Compare What are four Branched C O Straight chain H OH groups of biochemicals chain H C C important for living things? OH H OH H C C H OH

Glucose is a simple carbohydrate. Cellulose and glycogen are complex carbohydrates madePH0 up5SECMPP01057 of chains cof glucose. Each The Format Group, LLC PH05SECMPP01057a PH0hexagon5SECMPP01057 in theb diagram represents one glucose unit. 05/14/03 The Format Group, LLC The Format Group, LLC 05/14/03 05/14/03 The simple carbohydrates, including glucose, are made of carbon, hydrogen, and oxygen. The carbon atoms form READING CHECK a ring. Complex carbohydrates can have hundreds or thou- 7. Describe What are sands of sugar molecules held together by chemical bonds. carbohydrates Cellulose is part of the rigid structure of the cell walls of plants. Animals use glycogen to supply energy to muscles.

LIPIDS Lipids are biochemicals that do not dissolve in water. Fats, oils, and waxes are examples of lipids. One of the functions of lipids in living things is to store energy. It can be unhealthy to eat too many lipids, but some fats and oils are part of a healthy diet. READING CHECK Lipids store extra energy in the body. This energy can be 8. Describe What are lipids? used later when the lipids take part in chemical reactions. As the lipid molecules break down, they release the stored chemical energy. In general, animals use fats for this pur- pose and plants use oils. When the organism has used up its carbohydrates, it can obtain energy from its lipids.

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Vegetable oil, meat, cheese, eggs, and milk are sources of lipids in your diet.

PROTEINS Most of the biochemicals found in living things are proteins. Proteins are biochemicals that are made of chains of building blocks called amino acids. Amino acids are small molecules made of carbon, hydrogen, oxygen and nitrogen. READING CHECK Some amino acid molecules also have sulfur atoms. 9. Describe What are Protein molecules are made of hundreds or thousands proteins? of amino acid molecules. Chemical bonds hold them together in long chains or complex webs. The function of a protein molecule depends on its shape. The shape of the protein molecule is determined by the exact order of amino acids in its structure. Proteins have many functions in living organisms. Enzymes are proteins that increase the rate of chemical reactions in a cell. Hemoglobin is a protein in red blood Say It cells that carries oxygen to the cells of the body. Proteins Research Find out how help carry materials through cell membranes hemoglobin can pick up and carry oxygen to the cells of Some proteins provide structure and strength. Your the body. Report your ﬁ nding hair and fingernails are made of protein molecules. The to the class. muscles that control the movement of your body are made primarily of protein molecules. Spiders use long chains of protein molecules to build light, but strong, silk webs.

Spider webs are made up of proteins that are shaped like long ﬁ bers.

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NUCLEIC ACIDS The largest molecules made by living things are nucleic acids. Nucleic acids are biochemicals made up of nucleotides. Nucleotides are molecules made of carbon, hydrogen, oxygen, nitrogen and phosphorus atoms. READING CHECK There are only five different types of nucleotides. 10. Describe What are They are combined in chains of up to millions of units in nucleic acids? nucleic acids. The order of the nucleotides determines the nucleic acid, just as the order of letters in a word determines the word. One of the functions of nucleic acids is to store genetic information. They are sometimes called the blueprints of life because they contain all of the information a cell needs to work. The patterns of the nucleotides are used by a cell when it builds proteins and other nucleic acids.

DNA AND RNA There are two kinds of nucleic acids: DNA and RNA. DNA molecules contain the genetic material of a cell. The DNA molecules in a single human cell contain millions of nucleotides and are about 2 meters long. This size allows the DNA molecules to store all of the information that a body’s cells need to function. READING CHECK DNA molecules are shaped as a double spiral, as 11. Describe What is stored shown in the figure below. Each nucleotide in one spiral in a DNA molecule? matches a specific nucleotide in the other spiral. When a cell needs to make a particular protein, information is copied from part of the DNA molecule. A second kind of nucleic acid, called RNA, is built using this information. The RNA molecule contains the information that the cell needs to build the protein molecules. RNA is involved in the actual building of proteins. READING CHECK 12. Describe What information does an RNA molecule contain?

Two strands of DNA are twisted in a spiral shape. Four different nucleotides make up the rungs of the DNA ladder.

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Section 4 Review NSES PS 1a, 1b, 1c SECTION VOCABULARY carbohydrate a class of energy-giving nutrients nucleic acid a molecule made up of subunits that includes sugars, starches, and ﬁber; called nucleotides contains carbon, hydrogen, and oxygen organic compound a covalently bonded hydrocarbon an organic compound composed compound that contains carbon only of carbon and hydrogen protein a molecule that is made up of amino lipid a type of biochemical that does not acids and that is needed to build and repair dissolve in water; fats and steroids are lipids body structures and to regulate processes in the body

1. Identify Complete the following table.

Type of carbon backbone Description The chain of carbon atoms forms a ring.

All carbon atoms are connected in a straight line.

The chain of carbon atoms separates into different directions.

2. Explain What group of hydrocarbons contains saturated compounds? What groups of hydrocarbons contain unsaturated compounds?

3. Identify Complete the following table.

Type of biochemical Description made of hundreds or thousands of amino acid molecules

one of the functions is to store genetic information

made of one or more simple sugar molecules

one of the functions in living things is to store energy

4. Identify and Describe What are two kinds of nucleic acids? What does each one do in living things?

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SECTION 2 ACIDS AND BASES 4. pH is the amount of hydronium ions in a 1. A hydrogen ion bonds with a water molecule solution. to form the hydronium ion. 5. Bases have high pH value, and acids have 2. sour taste low pH. 3. The left beaker should be colored blue, and 6. acid rain the right beaker yellow. 7. when a positive ion from a base combines 4. hydrogen gas and zinc chloride with a negative ion from an acid 5. ions 8. table salt and melting snow and ice 6. making fertilizers Review 7. Acids produce hydronium ions, and bases 1. In water, all the molecules of a strong acid produce hydroxide ions. break apart and form hydronium ions. When 8. hydroxide ions a weak base is dissolved in water, only a few 9. It could hurt you because chemicals such molecules break off to form hydroxide ions. as acids and bases can be corrosive or 2. When an acid and base combine, there is a poisonous. neutralization reaction. The hydrogen ions 10. The left beaker should be colored pale blue, from the acid combine with the hydroxide and the right beaker dark blue. ions from the base to form water and a salt. 11. blue 3. Sodium hydroxide  hydrochloric acid water  sodium chloride 12. household cleaners and fertilizers 4. with pH paper or a pH meter Review 5. The pH would be around 9 because bases + have high pH values. The stronger the base, 1. Acids produce hydronium (H3O ) ions, and bases produce hydroxide (OH–) ions. the higher the pH value. 6. A pH value below 7 indicates an acid; 2. Property Acids Bases the lower the number, the more acidic. Taste sour bitter This would be a bad place for fish to live, Color change of to red to blue because the water is too acidic. litmus paper Reaction yes no with metals SECTION 4 ORGANIC COMPOUNDS to produce 1. two or more carbon atoms linked to one hydrogen gas another Electrical yes yes conductivity 2. straight chain, branched chain, ring organic compounds that contain only carbon 3. hydronium 3. and hydrogen 4. No, because acids and bases both conduct electricity. 4. alkanes, alkenes, and alkynes Saturated hydrocarbons have only single 5. It turns blue because ammonia is a base. 5. covalent bonds between carbon atoms. 6. The acid or base is corrosive. Unsaturated hydrocarbons have double or 7. A base; rinse them with lots of water and tell triple covalent bonds between carbon atoms. the teacher. 6. carbohydrates, lipids, proteins, nucleic acids 7. biochemicals that are made of one or more SECTION 3 SOLUTIONS OF ACIDS AND simple sugar molecules BASES 8. biochemicals that do not dissolve in water; 1. the amount of acid or base dissolved in store energy water 9. biochemicals that are made of chains of 2. A strong acid has more molecules that break building blocks called amino acids apart when you dissolve the acid in water 10. biochemicals made up of nucleotides than a weak acid does. 11. all of the information that a body’s cells 3. water and a salt need to function

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12. the information that the cell needs to build 14. Dark area should be circled. protein molecules 15. Check for leaks in pipes and flaws in metal objects. Review 16. carbon-14 1. Type of carbon Description 17. one half-life, two half-lives backbone 18. A little less than half of the carbon-14 had Ring The chain of carbon atoms forms a ring. decayed after his death. Straight chain All carbon atoms are connected in a straight line. Review Branched chain The chain of carbon atoms 1. The atomic number for both isotopes is 92. separates into different The mass number of uranium-235 is 235, and directions. the mass number of uranium-238 is 238. 2. saturated compounds—alkanes, 2. First column, top to bottom: alpha, beta, unsaturated compounds—alkenes and alkynes gamma Second column: particle (electron) 3. Type of biochemical Description Proteins made of hundreds or Third column, top to bottom: 4, 0 thousands of amino acid Fourth column, top to bottom: 1-, 0 molecules Last column, top to bottom: low, high Nucleic acids one of the functions is to store genetic information 3. Gamma rays would work because they have Carbohydrates made of one or more the most penetrating power and enough simple sugar molecules energy to pass through metal. Alpha and Lipids one of the functions is to beta particles would be stopped by the store energy metal parts. 4. DNA—contains the genetic material of a cell; 4. One-fourth remaining indicates 2 half-lives RNA—contains the information that the cell or 2.6 billion years. needs to build protein molecules. SECTION 2 ENERGY FROM THE NUCLEUS 1. A large nucleus splits into two smaller Chapter 4 Atomic Energy nuclei, releasing energy. Their difference is three because three neu- SECTION 1 RADIOACTIVITY 2. trons are also produced. 1. Energy came from the uranium. 3. Some of the masses are changed into energy. 2. radioactive decay 4. a continuous series of nuclear fission 3. An alpha particle has two protons and two reactions neutrons. Mass number is the sum of the 5. by keeping some of the neutrons from hit- protons and neutrons in a nuclear particle or ting a uranium nucleus in a nucleus. 6. kinetic energy changed into mechanical 4. 224 energy, mechanical energy changed into 5. mass and charge electrical energy 6. It stays the same. 7. An explosion can blow a large amount 7. 5+ of radioactive fuel and waste into the 8. atoms that have the same number of protons atmosphere. but different number of neutrons 8. It has dangerous levels of radioactivity. 9. high-energy waves 9. carbon dioxide 10. They have more mass and charge, so they 10. Two or more nuclei that have small masses tend to interact with atoms more easily. combine to form a larger nucleus. 11. They penetrate matter deeply. 11. the core 12. to warn them if they have been exposed to 12. Scientists cannot yet control the high tem- radiation harmful enough to damage cells peratures well enough to use fusion. 13. follow the path of a process

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