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 Radiant: waves of the electromagnetic spectrum Energy can be easily converted from one form to another. 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).

Energy Energy is massless and does not take up space. Energy is measured by its effects on matter. Energy is defined as the ability to do work or put matter into motion. There are two types of mechanical energy: Kinetic: energy doing work Potential: stored energy

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 and ionic.

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.