Basic Chemistry

Matter and Energy Matter—anything that occupies space and has mass (weight) Energy—the ability to do work Chemical Electrical Mechanical Radiant

Composition of Matter Elements—fundamental units of matter 96% of the body is made from four elements Atoms—building blocks of elements

Atomic Structure Nucleus Protons (p+) Neutrons (n0) Outside of nucleus Electrons (e-) Figure 2.1

Atomic Structure of Smallest Atoms Figure 2.2

Identifying Elements Atomic number Atomic mass

Isotopes and Atomic Weight Have the same number of protons Vary in number of neutrons Figure 2.3

Isotopes and Atomic Weight Close to mass number of most abundant isotope Atomic weight reflects natural isotope variation

Radioactivity Radioisotope Heavy isotope Tends to be unstable Decomposes to more stable isotope Radioactivity—process of spontaneous atomic decay

Molecules and Compounds Molecule—two or more like atoms combined chemically Compound—two or more different atoms combined chemically Figure 2.4

Chemical Reactions Atoms are united by chemical bonds Atoms dissociate from other atoms when chemical bonds are broken

Electrons and Bonding Electrons occupy energy levels called electron shells Electrons closest to the nucleus are most strongly attracted Each shell has distinct properties

Electrons and Bonding Bonding involves interactions between electrons in the outer shell (valence shell) Full valence shells do not form bonds

Inert Elements Atoms are stable (inert) when the outermost shell is complete How to fill the atom’s shells Shell 1 Shell 2 Shell 3

Inert Elements Atoms will gain, lose, or share electrons to complete their outermost orbitals and reach a stable state Rule of eights Atoms are considered stable when their outermost orbital has 8 electrons The exception to this rule of eights is Shell 1, which can only hold 2 electrons

Inert Elements Figure 2.5a

Reactive Elements Valence shells are not full and are unstable Tend to gain, lose, or share electrons Allow for bond formation, which produces stable valence Figure 2.5b

Chemical Bonds Ionic bonds Form when electrons are completely transferred from one atom to another Ions Charged particles Anions Cations Either donate or accept electrons PLAY Ionic Bonds

+ – Ionic Bonds Na Cl Na Cl Sodium atom (Na) (11p+; 12n0; 11e–) Chlorine atom (Cl) (17p+; 18n0; 17e–) Sodium ion (Na+) Chloride ion (Cl–) Sodium chloride (NaCl) Figure 2.6

Chemical Bonds Covalent bonds Atoms become stable through shared electrons Single covalent bonds share one pair of electrons Double covalent bonds share two pairs of electrons PLAY Covalent Bonds

Examples of Covalent Bonds Figure 2.7a

Examples of Covalent Bonds Figure 2.7b

Examples of Covalent Bonds Figure 2.7c

Polarity Covalently bonded molecules Some are non-polar Electrically neutral as a molecule Some are polar Have a positive and negative side Figure 2.8

Chemical Bonds Hydrogen bonds Weak chemical bonds Hydrogen is attracted to the negative portion of polar molecule Provides attraction between molecules

Hydrogen Bonds Figure 2.9

Patterns of Chemical Reactions Synthesis reaction Atoms or molecules combine Energy is absorbed for bond formation Decomposition reaction Molecule is broken down Chemical energy is released PLAY Disaccharides

Synthesis and Decomposition Reactions Figure 2.10a

Synthesis and Decomposition Reactions Figure 2.10b

Patterns of Chemical Reactions Exchange reaction Involves both synthesis and decomposition reactions Switch is made between molecule parts and different molecules are made

Patterns of Chemical Reactions Figure 2.10c

Biochemistry: Essentials for Life Organic compounds Contain carbon Most are covalently bonded Example: Inorganic compounds Lack carbon Tend to be simpler compounds

Important Inorganic Compounds Water Most abundant inorganic compound Vital properties High heat capacity Polarity/solvent properties

Important Inorganic Compounds Salts Easily dissociate into ions in the presence of water Vital to many body functions Include electrolytes which conduct electrical currents

Dissociation of a Salt in Water Figure 2.11

Important Inorganic Compounds Acids Release hydrogen ions (H+) Are proton donors Bases Release hydroxyl ions (OH–) Are proton acceptors Neutralization reaction Acids and bases react to form water and a salt

pH Measures relative concentration of hydrogen ions pH 7 = neutral pH below 7 = acidic pH above 7 = basic Buffers—chemicals that can regulate pH change Figure 2.12

Important Organic Compounds Carbohydrates Contain carbon, hydrogen, and oxygen Include sugars and starches Classified according to size Monosaccharides Disaccharides Polysaccharides

Carbohydrates PLAY Disaccharides Figure 2.13a–b

Carbohydrates PLAY Polysaccharides Figure 2.13c

Carbohydrates Figure 2.14

Important Organic Compounds Lipids Contain carbon, hydrogen, and oxygen Carbon and hydrogen outnumber oxygen Insoluble in water

Lipids Common lipids in the human body Neutral fats (triglycerides) Found in fat deposits Composed of fatty acids and glycerol Source of stored energy PLAY Lipids

Lipids Figure 2.15a

Lipids Common lipids in the human body (continued) Phospholipids Steroids

Lipids Figure 2.15b

Lipids Cholesterol The basis for all steroids made in the body Figure 2.15c

Important Organic Compounds Proteins Made of amino acids Contain carbon, oxygen, hydrogen, nitrogen, and sometimes sulfur Figure 2.16

Proteins Account for over half of the body’s organic matter Provide for construction materials for body tissues Play a vital role in cell function

Proteins Amino acid structure Contain an amine group (NH2) Contain an acid group (COOH) Vary only by R groups

Proteins Fibrous proteins Also known as structural proteins Appear in body structures Examples include collagen and keratin Stable Figure 2.17a

Proteins Globular proteins Also known as functional proteins Function as antibodies or enzymes Can be denatured Figure 2.17b

Enzymes Act as biological catalysts Increase the rate of chemical reactions Figure 2.18a

Enzymes PLAY Chemistry of Life® Enzymes Animation Figure 2.18b

Important Organic Compounds Nucleic Acids Provide blueprint of life Nucleotide bases A = Adenine G = Guanine C = Cytosine T = Thymine U = Uracil Make DNA and RNA Figure 2.19a

Nucleic Acids Deoxyribonucleic acid (DNA) Organized by complimentary bases to form double helix Replicates before cell division Provides instructions for every protein in the body Figure 2.19c

Important Organic Compounds Adenosine triphosphate (ATP) Chemical energy used by all cells Energy is released by breaking high energy phosphate bond ATP is replenished by oxidation of food fuels

Adenosine Triphosphate (ATP) Figure 2.20a