| A | B |
|---|
| atom | the basic unit of matter |
| nucleus | the center of the atom where strong forces bind protons and neutrons |
| electron | a negatively charged particle |
| element | a pure substant that consists entirely of one type of atom |
| isotope | atoms of the same element that differ in the number of neutrons they contain |
| compound | is a substance formed by the chemical combination of two or more elements in definite proportions |
| ionic bond | is formed when one or more electrons are transferred from one atom to another |
| ion | that has a positive or negative charge |
| covalent bond | forms when electrons are shared between atoms |
| molecule | is the smallest unit of most compounds |
| van der Waals forces | when molecules are close together, a slight attraction can develop between the oppositely charged regions of nearby molecules |
| cohesion | is an attraction between molecules of the same substance |
| adhesion | is an attraction between molecules of different substances |
| mixture | is a material composed of two or more elements or compounds that are physically mixed together but not chemically combined |
| solution | when the ions gradually decome dispersed in the water, forming a type of mixture called a solution |
| solute | the substance that is dissolved |
| solvent | the substance in which the solute dissolves |
| suspension | a mixture of water and nondisolved material |
| pH scale | a measurment system to indicate the concentration of H+ iions |
| acid | any compound that forms H+ ions |
| base | is a compund that produces hydroxide ions in solution |
| buffer | are weak acids or bases that can react with strong acids or pases to prevent sharp, sudden changes |
