Question | Answer |
chemistry | the science that describes matter, it's prooperties, it's physical changes and it's energy changes that accompany it. |
matter | anything that has mass and occupies space |
inanimate matter | non-living matter |
animate matter | living matter |
energy | the capacity to do work or transfer heat |
scientific law | a general statement based on the observation of matter to which no know exceptions exist |
law of conservation of mass | mass is always conserved, it is neither lost or gained, chemical reactions do not add or lose mass |
law of conservation of energy | energy can not be created or lost in a reaction or change, it only changes from one form to another |
law of conservation of matter and energy | the combined amount of matter and energy available in the universe is fixed |
element | composed of extremely small indivisible particles called atoms |
atom | the smallest part of an element that maintains the chemical identity of the element through all changes |
fundemental parts of an atom | electrons, protons and neutrons |
molecule | the smallest part of an element or compound that can have a stable existence |
polyatomic | molecules that contain 2 or more atoms |
compounds | made up of atoms of more than one element |
solids | a state of matter that is rigid and has definite structure, molecules are tightly arranged in a matrix, volume does not change much with heat |
liquids | a state of matter where the molecules are randomly oriented, takes the shape of a container, is very hard to compress because the molecules are close together |
gas | a state of matter where molecules are arranged far apart, is capable of infinite expansion, easily compressed and fills a container completely |
extensive properties | properties that depend on the quantity, volume or mass |
intensive properties | properties that do not depend on the quantity, eg. melting point is always the same no matter how much you have |
substances | matter in which all samples have identical composition |
mixtures | two or more substances combined in which each reatins its own composistion and properties |
homogeneous mixture | a mixture that has uniform properties throughout |
heterogeneous mixture | a mixture that is not uniform throughout |
compounds | substances composed of two or more elements in a definite ratio and can be decomposed into it constituant elements |
law of definite proportions (or constant composition) | different samples of any pure compound always contain the same elements in the same proportions by mass |
SI units | system international units |
mass | the measure of the quantity of matter in a body regardless of gravity |
weight | measure of the gravitational attraction of a body |
accuracy | how closely measured values agree with the correct value |
precision | how closely individual measurements agree with each another |
temperature | a measure of intensity of heat |
specific gravity | the ratio of the density of a sunstance compared to the desity of water at the same temperature |
specific heat | the amount of heat required to raise 1g of a substance 1 degree in Celsius |
Calorie (cal) | exactly 4.184 joules (J) Origionally defined at the amount of heat required to raise the temp. of 1g of water from 14.5 deg C to 15.5 deg C |
endothermic | a process that absorbs heat |
exothermic | a process that releases heat |
heat | a form of energy that flows between two samples of matter because of their difference in temperature |
heat capacity | the amount of heat required to raise a body one degree in celsius |
Joule (J) | unit of energy in the SI system. equals 1kg * m^2/s^2 which is 0.2390 cal |
kinetic energy | energy that matter pocesses by virtue of its motion |
potential energy | energy that matter pocesses by virtue of its position, condition or composition |
chemical formula | a combination of element symbols that indicate the chemical composition of a substance |
composition stoichiometry | describes the quantitative (mass) relationships among elements in compounds |
allotropes | different forms of the same element in the same physical state |
anhydrous | without water |
anion | ion with negative charge |
cation | ion with positive charge |
atomic mass unit (amu) | one twelfth of the mass of carbon-12, a umit stating atomic and formula weights |
avagardos number | 6.022 X 10^23 units |
ion | an atom or group of atoms that carries a charge |
mole | 6.022 X 10^23 formula units of a substance. The mass in grams of one mole is equal to the formula weight of a substance |