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Principles of Chemistry. Chapter 2 Anatomy & Physiology. The Nature of Matter. Matter is anything that occupies space and has mass. Matter is divided into three classes : elements, compounds and mixtures. Elements are the simplest pure substances.
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Principles of Chemistry Chapter 2 Anatomy & Physiology
The Nature of Matter • Matter is anything that occupies space and has mass. • Matter is divided into three classes: elements, compounds and mixtures. • Elements are the simplest pure substances. • Compounds are made of two or more elements chemically combined. • Mixtures are made of two or more substances that retain their own properties.
Matter • Matter can exist in three states: gas, liquid, or solid. • A gas has no definite shape or volume. • A liquid has a definite volume, but no definite shape. • A solid has a definite shape and volume.
Forms of Energy • There are four forms of energy: • Chemical: stored in bonds of chemicals • Electrical: movement of electrons • Mechanical: moving matter (kinetic & potential) • Radiant: waves of the electromagnetic spectrum • Energy is the ability to do work & can be easily converted from one form to another. • Energy is massless and does not take up space & is measured by its effects on matter. • In the body, chemical energy from food is converted to ATP in the cell and used to produce electric energy (nerve impulse) and mechanical energy (muscle contraction).
Elements • All matter is composed of a limited number of pure substances called elements. • Elements cannot be broken down into simpler substances by chemical means & each is composed of a unique atom. • Elements are arranged according to their atomic numbers and physical characteristics in the periodic table.
Atoms • Atoms are the smallest unit of an element. • They can exist alone or in combination with other elements. • Atoms are made of three basic subatomic particles: electrons, protons, and neutrons. • Subatomic particles can be distinguished by their location in the atom, their charge and their mass.
Subatomic Particles • Protons are located in the nucleus or center of the atom, they have a positive charge and make up half of the atomic mass. • Neutrons are also in the nucleus, have a neutral charge and make up the other half of the atomic mass. • Electrons orbit the nucleus and have a negative charge and no measurable mass.
Identifying Elements • Every element has a specific atomic mass, atomic number and atomic symbol. • The atomic mass is the combined mass of the protons and neutrons. • The atomic number is the number of protons in an element. • The atomic symbol is a one, two or three letter combination used to represent the element.
Isotopes • Although all atoms of an element have the same number of protons, the number of neutrons can vary, this is called an isotope. • Isotopes have the same atomic number, but different atomic masses due to different #s of neutrons. • Some isotopes are radioactive and are used as tools in the treatment and diagnosis of disease.
Chemical Compounds • The molecule is the basic structural unit of a compound. • The molecular formula tells the specific number and arrangement of atoms in a compound. • Ex. Glucose and Fructose (both are C6H12O6)
Atomic Energy Levels • The electrons orbiting the nucleus move at very high speeds in a number of different energy levels. • The number and arrangement of the electrons in an atom’s outermost shell is responsible for how an atom reacts with other atoms.
Atomic Energy Levels • Each energy level has a specific number of electrons it can hold. • 1st Energy Level = 2 electrons • 2nd Energy Level = 8 electrons • 3rd Energy Level = 8 or 18 electrons • Atoms with full outer energy levels do not attract or transfer electrons and are considered stable. • Atoms without full outer energy levels will transfer or attract electrons until a full outer energy level is obtained.
Chemical Bonding • A chemical bond is formed when electrons are transferred or shared between two or more atoms. • The two types of bonds WITHIN molecules are covalent (shared e-) and ionic (transferred e-).
Ionic Bonds • When electrons are transferred an imbalance of charges occurs and an ion is formed. • An ion is a charged atom. • Ionic bonds form between oppositely charged ions. • Positively charged ions are called cations. • Negatively charged ions are called anions.
Covalent Bonds • Compounds formed by the sharing of electrons have covalent bonds. • In a covalent bond, each atom of the pair shares an electron with the other. • The shared pair of electrons orbit the nuclei of both atoms. • Single, double and triple covalent bonds can be formed between atoms.
Hydrogen Bonds • Hydrogen bonds are extremely weak bonds between MOLECULES that form when a hydrogen atom bound to a nitrogen or oxygen atom is attracted to another oxygen or nitrogen atom. • Hydrogen bonding is common in water molecules. • Hydrogen bonding is essential in maintaining the structure of protein molecules.
Types of Reactions • Types of reactions: • Synthesis – two or more substances combine to create something new • Decomposition – complex substances are broken down into two or more substances • Single Replacement – one substance replaces another in a compound • Double Replacement – positive and negative portions of two compounds interchange.
Oxidation-Reduction Reactions • Oxidation-reduction reactions are chemical reactions that supply the energy for the body • Oxidation reactions release electrons while in reduction the same electrons are gained by another atom. • Cellular respiration contains a large number of oxidation-reduction (redox) rxn. ATP is formed from ADP and vice versa. • Remember OIL RIG.
Inorganic Compounds • Inorganic compounds lack carbon and tend to be small, simple molecules. • Important inorganic compounds include: • Water • Salts • Acids • Bases
Water • Water is the most abundant inorganic compound in the body. • It has four important properties: • High heat capacity • Polarity/solvent properties • Chemical reactivity • Cushioning
Salt • The salts of many metal elements are found in the body including calcium and phosphorous in the bones and teeth. • Salts are easily ionized in water and are able to perform vital functions for the body including nerve impulses, muscle contractions, & eliminating wastes through urine. • All salts are electrolytes, substances that can conduct an electric charge.
Acids • Acids are electrolytes that have a sour taste and can dissolve metal. • Acids release large amounts of hydrogen ions. They are very low on the pH scale which goes from 1 to 14 (7 being neutral). • Acids are very important in the process of digestion, and in maintaining the blood’s pH levels.
Bases • Bases are electrolytes that have a bitter taste and produce hydroxide ions (-OH). They have a higher pH. • Bases play an important role in maintaining the body’s pH levels, especially in the red blood cells.
Organic Compounds • Organic compounds are formed by different combinations of the elements hydrogen, oxygen, nitrogen and carbon. • All organic compounds contain carbon. • Organic compounds can be broken down into four groups: Carbohydrates, lipids (fats), proteins, and nucleic acids.
Carbohydrates • Carbohydrates are a source of energy for the cell. • They consist of sugars and starches. • Ex. Glucose which is present in the fluid surrounding the cell • Carbohydrates are made of oxygen, hydrogen and carbon.
Lipids • Lipids are formed from fatty acids and glycerol molecules (also made of C, H & O). • Lipids store and supply energy for the body when needed. • A special characteristic of lipids is that they are insoluble in water. • Lipids are used in cell membranes for their ability to keep regulate water movement in and out of the cell.
Proteins • Protein molecules are made up of large chains of amino acids. • Proteins are the structural molecules of the cells and the chemical compounds that control biological reactions in the body. • Proteins that control metabolic functions are called enzymes.
Nucleic Acids • Ribonucleic acid (RNA) and Deoxyribonucleic acid (DNA) are examples of the last group of organic compounds. • RNA is responsible for protein synthesis. • DNA is responsible for the formation of protein molecules and carries hereditary information.
Adenosine Triphosphate (ATP) • ATP is a type of nucleic acid molecule. ATP is made of an adenine base, a ribose sugar, and three phosphate groups. • The synthesis of ATP provides the storage of chemical energy for all body cells. • The energy is stored when a phosphate group bond is formed and released when the phosphate bond is broken.
