Chemistry of Life Vocabulary
Atom - A unit of matter, the smallest unit of an element, having all the characteristics of that element and consisting of a central, positively charged nucleus surrounded by a system of electrons.
Nucleus - The positively charged central region of an atom, composed of protons and neutrons and containing almost all of the mass of the atom.
Electron - A very small subatomic particle having negative electric charge
(mass = 9.1066 × 10-28 grams, width = 2.82 x 10-15 m)
Proton - A positively charged subatomic particle that makes up all or part of the nucleus of an atom (mass 1,836 times that of the electron, width = 2 × 10--14- m)
Neutron -A neutral subatomic particle , having no electric charge. Very close in mass to a proton. It and the proton form nearly the entire mass of atomic nuclei.
Element -A substance composed of atoms having an identical number of protons in each nucleus. Elements cannot be reduced to simpler substances by normal chemical means.
Compound -Substances composed of two or more elements which have fixed and definite physical properties, such as density. The elements in compounds cannot be separated by simple physical or mechanical means, but only by chemical treatment.
Molecule - The smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms; a group of like or different atoms held together by chemical forces.
Chemical bond - Any rearrangement of electrons in two atoms that generates a force, causing the atoms to be bound to each other, forming a molecule. Such as especially the ionic bond, covalent bond, and metallic bond, by which atoms or ions are bound in a molecule or crystal.
Polarity - Tendency of a molecule, or compound, to be attracted or repelled by electrical charges because of an asymmetrical arrangement of atoms around the nucleus.
Surface tension -The force acting in the surface of a liquid, tending to minimize the area of the surface. This force causes the capillary rise of liquids in fine tubes and wicks, and the curvature of free-liquid surfaces.
Cohesion -Intermolecular attraction between like-molecules. Cohesion explains phenomena such as surface tension and capillary action.
Adhesion -the molecular attraction exerted between dissimilar molecules in contact. Example: Water clinging to a spider web.
Mixture -a physical combination of two or more pure substances (i.e., elements or compounds). A mixture is distinguished from a compound, which is formed by the chemical combination of two or more pure substances in a fixed, definite proportion.
Solution - A homogeneous mixture of two or more components whose properties vary continuously with varying proportions of the components. Example: dissolving salt to water changes the boiling and freezing point based on how much salt is dissolved
Solute -A substance dissolved in another substance, usually the component of a solution present in the lesser amount.
Solvent -A substance in which another substance is dissolved, forming a solution. A substance, usually a liquid, capable of dissolving another substance.
Suspension -a mixture in which fine particles are suspended in a fluid where they are supported by buoyancy. Common suspensions include sand in water, fine soot or dust in air, and droplets of oil in air. Particles in a suspension precipitate if the suspension is allowed to stand undisturbed.
pH scale -A logarithmic scale for determining the acidity or alkalinity of a substance, from 0 (virtually pure acid) to 7(neutral) to 14 (virtually pure base).
Acid –substance having a pH of less than 7, and a relatively high concentration of hydrogen ions (H+). Characterized by a sour taste, the ability to turn blue litmus red, and the ability to react with bases and certain metals to form salts.
Base –Substance having a pH of greater than 7, and gives off hydroxyl ions (OH-) when dissolved in water. Characterized by a bitter taste, a slippery feel, the ability to turn litmus blue, and the ability to react with acids to form salts.
Buffer - Solution usually containing a weak acid and its conjugate weak base, or a salt, of such a composition that the pH is held constant within a certain range. An example is a solution containing acetic acid (CH3COOH) and the acetate ion
Carbohydrate - Any of a group of organic compounds that includes sugars, starches, celluloses, and gums and serves as a major energy source in the diet of animals. They contain only carbon, hydrogen, and oxygen, usually in the ratio 1:2:1.
Lipid - A group of organic molecules that includes fats, oils, and waxes. Lipids do not dissolve in water. In animals, including humans, lipids store energy and form parts of cell structures, such as cell membranes. Made up of mostly Carbon and Hydrogen, with some oxygen.
Protein - A macromolecule made up of amino acids that are joined by peptide bonds. They contain carbon, hydrogen, oxygen, nitrogen, and usually sulfur and are composed of one or more chains of amino acids. Proteins are important parts of all living cells and include many substances, such as enzymes, hormones, and antibodies, that are necessary for the proper functioning of an organism. They are essential in the diet of animals for the growth and repair of tissue and can be obtained from foods such as meat, fish, eggs, milk, and legumes.
Nucleic acid - An acidic, chainlike biological macromolecule consisting of multiply repeated units of phosphoric acid, sugar, and nitrogen bases. Nucleic acids as a class are involved in the preservation, replication, and expression of hereditary information in every living cell. There are two types of nucleic acid: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
DNA - Deoxyribonucleic acid; a large molecule made up of two long chains twisted together. Carries the cells genetic information and heredity. Made up of phosphate, ribose (sugar) units with Nitrogen bases.
RNA - Ribonucleic acid; a long single stranded molecule made up of phosphate, ribose (sugar) units with Nitrogen bases. RNA provides a code for protein synthesis and the transmission of genetic information.
Chemical reaction - A process in which atoms of the same or different elements rearrange themselves to form a new substance. While they do so, they either absorb heat or give it off.
Reactant - A substance participating in a chemical reaction, especially a directly reacting substance present at the initiation of the reaction.
Product - A substance resulting from a chemical reaction.
Activation energy –minimum amount of energy required for a chemical reaction to happen.
Substrate - a molecule which is acted upon by an enzyme
Catalyst - A substance, usually used in small amounts relative to the reactants, that modifies and increases the rate of a reaction without being consumed in the process.
Enzyme - Enzymes are proteins that act as biological catalysts, or chemicals that speed up the rate of reaction between substances without themselves being consumed in the reaction. They are vital to bodily functions such as digestion, and they make possible processes that normally would occur at temperatures so high they would threaten the well-being of the body.