← Gen. Bio. Chapter 2-Part 1 Export Options Alphabetize Word-Def Delimiter Tab Comma Custom Def-Word Delimiter New Line Semicolon Custom Data Copy and paste the text below. It is read-only. Select All atom The smallest particle of matter that still retains the properties of an element (p. 35). proton Positively charged particle found in the nucleus of the atom that has a mass of ~1 amu (p. 35). neutron Neutral particle found in the nucleus of an atom that has a mass of ~1 amu (p. 35). electron A negatively charged particle in constant motion around the nucleus (p. 35). nucleus The center of the atom (p. 35). element A pure substance that consists entirely of one type of atom (p. 36). isotopes Atoms of the same element that differ in the number of neutrons they contain (p. 36). mass number The sum of the protons and neutrons in the nucleus of an atom (p. 36). compound A substance formed by the chemical combination of two or more elements in definite proportions (p. 37). ionic bond This bond is formed when one or more electrons are transferred from one atom to another (p. 38). covalent bond This bond is formed when electrons are shared by atoms (p. 38). molecule The structure that results when atoms are joined together by covalent bonds (p. 38). van der Waals forces Intermolecular forces of attraction that develop between the oppositely charged regions of molecules that are close together (p. 39). polar molecule A molecule in which the charges are unevenly distributed (p. 40). hydrogen bond An example of this type of bond is the attraction between the hydrogen atom on one water molecule and the oxygen atom on another water molecule (p. 41). cohesion An attraction between molecules of the same substance; water exhibits this property because of hydrogen bonding (p. 41). adhesion An attraction between molecules of different substances (p. 41). mixture A material composed of two or more elements or compounds that are physically mixed together but not chemically combined; salt and pepper stirred together is an example (p. 41). solution Mixture of two or more substances in which the molecules of the substances are evenly distributed (p. 42). solvent Substance in which a solute is dissolved to form a solution (p. 42). solute Substance that is dissolved in a solvent to make a solution (p. 42). suspension Mixture of water and nondissolved materials (p. 42). ion An atom that has a positive or negative charge (p. 38). group A vertical column of the periodic table of the elements; also called a "family." period A horizontal row of the periodic table of the elements. octet rule Atoms tend to gain, lose or share electrons so as to have eight electrons in their outer electron shell. valence electrons The outermost electrons of an atom, which are important in determining how the atom reacts chemically with other atoms. pH Scale A measurement system that indicates the concentration of H+ ions in solution; ranges from 0-14. Acid Any compound that forms H+ ions in solution; a solution that has a pH value below 7. Base Any compound that produces OH- ions in solution; a solution that a pH value above 7. Buffer A weak acid or base that can react with strong acids or bases to prevent sharp, sudden changes in pH.