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Chapter Two Chem
Matter | anything that takes up space and has mass, created by God out of nothing |
Properties | related to the physical relationships among the particles of matter |
Physical Properties | measured without changing the composition of the matter |
Chemical Properties | related to how matter changes in the presence of other matter, measured by a change in composition when a new substance is formed from the old one (how easily does something rust, burn, rot, decompose) |
Physical Changes | changes that occur in matter without changing the identity of the material, can often be reversed |
color | physical property |
shape | physical property |
density | physical property |
ductility | physical property |
flammability | chemical property |
solubility | physical property |
supports combustion | chemical property |
sour taste | physical property |
melting point | physical property |
odor | physical property |
can neutralize a base | chemical property |
how easily does it rot, burn, or decompose? | chemical |
Chemical Changes | change the identity of the matter, start off with one compound and end up with something different with different chemical and physical properties, not easily reversed |
Pure SUbstances | consist of one type of matter, cannot be separated into other kinds of matter by physical means, elements, compounds |
Mistures | can be separated by physical means into 2 or more pure substances, divided into homogeneous and heterogeneous |
Elements | made of atoms and represented by symbols (H, Cu, N), cannot be broken down into simpler substances by ordinary chemical means |
Compounds | two or more elements chemically bound together (water, carbon dioxide, sugar, table salt) |
Homogeneous Mixtures | show only one phase (appearance) throughout, also called SOLUTIONS, sugar water, air, salt water, cola |
Heterogeneous Mixtures | have distinct regions called phases, granite, Italian dressing |
Monatomic Elements | an element whose atoms do not combine with other atoms, one atom in the formula, Ne, He, Ar, Xe |
Diatomic Elements | an element whose atoms bond into two-atom units, H, N,O, F, Cl, Br, I |
Polyatomic Elements | elements whose atoms bond into multi-atom units |
Molecules | smallest individual units in many compounds, made of two or more elements chemically bound together, can be made of the same element or two different elements |
Formulas | represent compounds and tell what type of element and how many atoms of each type of element are in an individual unit of the compound |
Coefficients | the numbers in front of a formula and refer to the entire unit |
Energy | the ability to do work, related to the force that matter generates and the resulting actions of that force |
Mechanical Energy | possessed by objects that are moving (kinetic energy) or have the potential to move (potential energy) |
thermal energy | heat energy |
sound (acoustic) energy | particles move in a periodic way like waves |
electrical energy | movement of charged particles |
radiant energy | radiates out from the sun |
wind energy | from the wind |
electromagnetic energy | from the sun |
nuclear energy | from the nucleus of an atom |
chemical energy | stored in chemical bonds |
exothermic reactions | release energy and feel hot to the touch (hand warmers) |
endothermic reactions | absorb energy and feel cold to the touch (cold packs) |
thermodynamics | the study of the flow of energy, the movement and conversion of energy |
Law of Energy Conservation (First Law of Thermodynamics) | energy can neither be created nor destroyed only changed from one form to another (E=mc2) |
Second Law of Thermodynamics | during energy transformations, some energy changes to an unusable form, go from order to disorder |
entropy | the measure of disorder or randomness in a system, entropy increases over time |
system | a portion of the universe under study |
diffusion | evenly spreading out particles over time through motions (food coloring in water) |
kinetic energy | energy of motion, depends on mass and velocity of an object |
total internal energy of an object | =KE + PE |
temperature | the average KE of a system's particles, IS NOT related to number of particles but how much the average is per particle |
thermal energy | the sum of KE of an object's particles, IS related to number of particles, more particles=more heat energy, flows rom HOT to COLD, to cool something down it has to "send" its heat to a cooler object |
heat transfer | the transfer of thermal energy between two objects, amount of heat transferred is determined by temp difference between the two objects as well as the mass of the hotter object |