Question | Answer |
acid | a compound that yields hydrogen ions in solution |
alkali metals | lithium, sodium, and potassium; common as hydroxides |
alloy | a metal composed of two or more metallic elements |
atom | the smallest particle of matter that cannot be subdivided by chemical reactions |
atomic number | the number of protons in an atomic nucleus; the different chemical elements have different atomic numbers |
base | a compound that yields hydroxyl (OH~)ions in solution |
Boyle's law | the volume of a gas varies inversely with pressure |
carbon dioxide | CO2 is a colorless, noncombustible gas under normal conditions |
catalyst | a substance that accelerates a chemical reaction, without itself being a reactant |
Charles' law | the volume of a gas varies directly with temperature |
combustion | rapic oxidation that releases heat and light |
compound | a substance formed by the chemical union of several chemical elements |
decomposition | a chemical reaction in which a compound is broken down into simpler compounds or elements |
density | mass per unit volume of a substance |
diffusion | the mixing of different substances, commonly in a liquid or gas |
distillation | the process of purification in which an impure substance is heated to vapors, which are collected and condensed |
electrolysis | a chemical change brought about by an electric current; used to separate chemical elements |
electron | a negatively charged, subatomic particle; electrons form a cloud around the atomic nucleus. Electron movement constitutes electrical current. |
element | a substance that cannot be decomposed to simpler substances |
evaporation | a change of state from a solid or liquid to a gas |
freezing point | the temperature at which a liquid changes to a solid |
hydrocarbons | compounds of carbon and hydrogen |
hydrolysis | chemical decomposition of a compound by reaction with water |
ion | a charged atom or group of atoms formed by the gain or loss of electrons |
isotope | ...of an element have the same number of protons and show the same chemical behavior, but they differ in the number of nuclear neutrons and thus in atomic weight; they may be stable or radioactive |
litmus | paper that turns red in acid and blue in alkaline solution |
mixture | substances mixed without a chemical reaction; the substances can be in any proportion |
molecule | the smallest particle of a compound, composed of several bonded atoms |
neutron | a subatomic particl of zero charge that occurs in the atomic nucleus |
organic compound | a compound with interconnected carbon atoms |
oxidation | the addition of oxygen to a substance |
pH | a number indicating the concentration of hydrogen ions in a solution. A pH of 7 is neutral, less than 7 is acidic and greater than 7 is alkaline |
proton | a subatomic particle with a positive charge, occurring in the atomic nucleus |
saturated | describes a solution that contains as much solute as possible |
solute | the substance dissolved in a solution |
solvent | the pure liquid within a solution |
sublimation | the change from a solid to a gas, without an intermediate liquid |
synthesis | the formation of a compound by combining elements or simpler compounds |
asteroid | a minor planet or planetary fragment; most of the thousands of known asteroids are between the orbits of Mars and Jupiter |
cluster | a concentration of stars; some globular clusters contain thousands of stars |
comet | a diffuse body that glows with a prominent tail when its orbit brings it near the sun |
constellation | an apparent group of stars |
eclipse | the obscuring of light from a celestial body by the passage of another body between it and the observer |
galaxy | an astronomical system composed of billions of stars; galaxies are classified as spiral, elliptical, and irregular |
latitude | refers to the degrees north or south of the equator |
light-year | the distance light travels in one year, about 6x10(12) |
longitude | refers to the degrees east or west of the prime meridian at Greenwich, England |
luminosity | the intrinsic brightness of a star relative to the brightness of the sun |
meteor | the streak of light produced by the passage of an interplanetary particle through the earth's atmosphere |
meteorite | a rock from interplanetary space found on the earth's surface |
milky way | the spiral galaxy to which our solar system belongs |
nebula | a cloud of gas or dust in interstellar space |
nova | a star that suddenly becomes many times brighter than usual |
quasar | quasi-stellar radio source; a distant object with extraordinary luminosity |
star | a large, hot, glowing body of gases |
sunspot | a darker patch observed on the surface of the sun |
tide | the rise and fall of the ocean due to gravitational attraction by the moon and sun |