Download Chemistry of Life Vocabulary

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)
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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.