Download Ch. 2 Vocabs

Honors Biology I
Chapter 2 Vocab
Section 1: Composition of Matter
 Matter: anything that has mass and takes up space
 Mass: a measure of the amount of matter in an object; a fundamental property of an
object that is not affected by the forces that act on the object, such as gravity
 Element: a substance that cannot be separated or broken down into simpler substances by
chemical means; all atoms of an element have the same atomic number
 Atom: the smallest unit of an element that maintains the chemical properties of that
element
 Nucleus: in a eukaryotic cell, a membrane- bound organelle that contains the cell’s DNA
and that has a role in processes such as growth, metabolism, and reproduction
 Proton: a subatomic particle that has a positive charge and that is located in the nucleus
of an atom; the number of protons of the nucleus is the atomic number, which determines
the identity of an element
 Neutron: a subatomic particle that has no charge and that is located in the nucleus of an
atom
 Atomic number: the number of protons in the nucleus of an atom; the atomic number is
the same for all atoms of an element
 Mass number: the sum of the numbers of protons and neutrons in the nucleus of an atom
 Electron: a subatomic particle that has a negative charge
 Orbital: a region in an atom where there is a high probability of finding electrons
 Isotope: an atom that has the same number of protons, same atomic number, as other
atoms of the same element do but that has a different number of neutrons and a different
atomic mass
 Compound: a substance made up of atoms of two or more different elements joined by
chemical bonds
 Chemical bond: the attractive force that holds atoms or ions together
 Covalent bond: a bond formed when atoms share one or more pairs of electrons
 Molecule: a group of atoms that are held together by chemical forces; a molecule is the
smallest unit of matter that can exist by itself and retain all of a substance’s chemical
properties
 Ion: an atom, radical or molecule that has gained or lost one or more electrons and has a
negative or a positive charge
 Ionic bond: the attractive forces between oppositely charged ions, which form when
electrons are transferred from one atom to another
Section 2: Energy
 Energy: the capacity to do work
 Chemical reaction: the process by which one or more substances change to produce one
or more different substances
 Reactant: a substance or molecule that participates in a chemical reaction
 Product: a substance that forms in a chemical reaction
 Metabolism: the sum of all chemical processes that occur in an organism
 Activation energy: the minimum amount of energy required to start a chemical reaction
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Catalyst: a substance that chang4s the rate of a chemical reaction without being
consumed or changed significantly
Enzyme: a type of protein or RNA molecule that speeds up metabolic reactions in plant
and animals without being permanently changed or destroyed
Redox reaction: a reaction in which electrons are transferred between atoms; also known
as an oxidation- reduction reaction
Oxidation reaction: a chemical reaction in which a reactant loses one or more electrons
such that the reactant becomes more positive in charge
Reduction reaction: a chemical change in which electrons are gained, either by the
removal of oxygen, or the addition of electrons
Section 3: Water and Solutions
 Polar: describes a molecule with opposite charges on opposite ends
 Hydrogen bond: the intermolecular force occurring when a hydrogen atom that is bonded
to a highly electronegative atom of one molecule is attracted to two unshared electrons of
another molecule
 Cohesion: the force that holds molecules of a single material together
 Adhesion: the attractive forces between tow bodies of different substances that are in
contact with each other
 Capillarity: the attraction between molecules that results in the rise of a liquid in small
tubes
 Solution: a homogeneous mixture throughout which tow or more substances are
uniformly dispersed
 Solute: in a solution, the substance that dissolves in the solvent
 Solvent: in a solution, the substance in which the solute is dissolved
 Concentration: the amount of a particular substance in a given quantity of a mixture,
solution, or ore
 Saturated solution: a solution that cannot dissolve any more solute under the given
conditions
 Aqueous solution: a solution in which water is the solvent
 Hydroxide ion: the OH- ion
 Hydronium ion: an ion consisting of a proton combine with a molecule of water; H3O+
 Acid: any compound that increases the number of hydronium ions when dissolved in
water; acids turn blue litmus paper red and react with bases and some metals to form salts
 Base: any compound that increases the number of hydroxide ions when dissolved in
water; bases turn red litmus paper blue and react with acids to form salts
 pH scale: a range of values that are used to express the acidity or alkalinity (basicity) of a
system; each whole number on the scale indicates a tenfold change in acidity; a pH of 7 is
neutral, a pH of less than 7 is acidic, and a pH of greater than 7 is basic
 buffer: a solution made form a weak acid and its conjugate base that neutralizes small
amounts of acids or bases added to it