Question | Answer |
actinide | the second series of inner transition elements which goes from thorium to lawrencium |
alkali metals | elements in group 1 of the periodic table |
alkaline earth metals | elements in group 2 of the periodic table |
Archimedes' principle | states that the buoyant force on an object is equal to the weight of the fluid displaced by the object |
atomic mass | average mass of an atom of an element' its unit of measure is the atomic mass unit, which is 1/12 the mass of a carbon-12 atom |
atomic number | number of protons in the nucleus of each atom of a given element; is the top number in the periodic table |
buoyant force | upward force exerted on an object immersed in a fluid |
catalyst | substance that can make something happen faster but is not changed itself |
chemical change | change in which the composition of a substance changes |
chemical property | characteristic that cannot be observed without altering the sample |
compound | a substance produced when elements combine and whose properties are different from each of the elements in it |
condensation | the process of changing from a gas to a liquid |
density | mass of an object divided by its volume |
deposition | the process by which a gas changes into a solid |
electron | negatively-charged particle that exists in an electron cloud formation around an atom's nucleus |
eletron cloud | region surrounding the nucleus of an atom, where electrons are most likely to be found |
element | substance that cannot be broken down into simpler substances |
freezing | change of matter from a liquid state to a solid state |
gas | matter that does not have a definite shape or volume; has particles that move at high speeds in all directions |
group | family of elements in the periodic table that have similar physical or chimical properties |
halogen | elements in group 17 of the periodic table |
heat | movement of thermal energy from a substance at a higher temperature to a substance at a lower temperature |
isotopes | two or more atoms of the same element that have different numbers of neutrons in their nuclei |
lanthanide | the first series of inner tansition elements which goes from cerium to lutetium |
law of conservation of mass | states that mass is neither created nor destroyed--and as result the mass of the substances before a physical or chemical change is equal to the mass of the substancs present after the change |
liquid | matter with a definite volume but no definite shape that can flow from one place to another |
mass number | sum of the number of protons and neutrons in the nucleus of an atom |
matter | anything that takes up space and has mass |
melting | change of matter from a solid state to a liquid state |
metal | element that is malleable, ductile, a good conductor of electricity, and generally has a shiny or metallic luster |
metalloid | element that shares some properites with both metals and nonmetals |
mixture | a combination of compounds and elements that has not formed a new substance and whose proportions can be changed without changing the mixture's identity |
neutron | electrically-neutral particle that has the same mass as a proton and is found in an aotm's nucleus |
noble gases | elements in group 18 of the periodic table |
nonmetal | element that is usually a gas or brittle solid at room temperature and is a poor conductor of heat and electricity |
Pascal's principle | states that when a force is applied to a confined fluid, an increase in pressure is transimitted euqally to all parts of the fluid |
period | horizontal row of elements in the periodic table whose properties change gradually and predictably |
physical change | change in which the form or appearance of matter changes, but not its composition |
physical property | characteristic that can be observed, using the five sense, without changing or trying to change the composition of s substance |
pressure | force exerted on a surface divided by the total area over which the force is exerted |
proton | positively-charged particle in the nucleus of an atom |
representative elements | elements in groups 1 and 2 and 13-18 in the periodic table that include metals, metalloids, and nonmetals |
semiconductor | element that does not conduct electricity as well as a metal but conducts it better than a nonmetal |
solid | matter with a definite shape and volume; has tightly packed particles that move mainly by vibrating |
sublimation | the process by which a solid changes directly into a gas |
substance | matter that has the same composition and properties throughout |
surface tension | the uneven forces acting on the particles on the surface of a liquid |
temperature | measure of the average kinetic energy of the individual particles of a substance |
transition elements | elements in groups 3-12 in the periodic table, all of which are metals |
vaporization | the process by which a liquid changes into a gas |
viscosity | a liquid's resistance to flow |