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Unit 2: Laws of the Universe (Part 1)

Terms in this set (33)

atom
smallest particle of an element, the basic unit of matter
diatomic element
made of two atoms bonded together
Ex: chlorine (Cl2)
monatomic element
made of separate, individual atoms
Ex: sodium (Na)
element
a pure substance made of only one KIND of atom
The Periodic Table
Ex: sodium (Na), chlorine(Cl2), oxygen(O2)
HOMOGENEOUS
compound
a pure substance made of two or more different KINDS of atoms
Ex: water (H2O), carbon dioxide (CO2), ammonia (NH3), methane (CH4)
HOMOGENEOUS
homogeneous mixture
a mixture in which substances are evenly distributed throughout the mixture
uniform composition
Ex: any "solution", salt water, NaCl (aq)
heterogeneous mixture
a mixture in which the composition is NOT uniform throughout (LAYERS)
Ex: oil and water
solid
definite shape
definite volume
particles arranged in a fixed, rigid geometric pattern
(s)
liquid
takes shape of container
definite volume
(l)
gas
takes shape of container
compressible (NO definite volume)
(g)
endothermic
a process or reaction that absorbs heat energy
Ex: ice melting
H2O(s) + heat --> H2O(l)
exothermic
a process or reaction that releases/gives off heat energy
Ex: water freezing
H2O(l) --> H2O(s) + heat
enthalpy
the heat content of a system
compressible
able to be squashed into a smaller space
physical property of gases
molecule
two or more atoms held together by sharing electrons
energy
the ability to do work or transfer heat
pure substance
a sample of matter, either an element or a compound, that consists of only one component with definite physical and chemical properties and a definite composition
mixture
sample of matter composed of two or more elements or compounds that are physically mixed together but not chemically combined
particle diagram
circles representing elements, compounds, or mixtures in the solid, liquid, or gas state
system
in experiments, the parts that are being studied (defined by the experimenter)
surroundings
in experiments, the environment around the system being studied
Bohr model
a model of an atom that describes the arrangement of subatomic particles; neutrons and protons in the nucleus and electrons in principle energy levels outside the nucleus
principle energy level (pel)
a value indicating the distance from the nucleus AND the energy that an electron has in an atom
chemical equation
a representation of a chemical reaction that uses symbols to show the relationship between the reactants and the products
Law of Conservation of Mass
matter cannot be created nor destroyed in any chemical or physical change
products
ending materials in a chemical reaction
reactants
starting materials in a chemical reaction
physical change
a change in a substance that does not change its identity; a change in phase
ex: melting, freezing, boiling, dissolving, condensing, crystallizing
chemical change
a change that occurs when one or more substances change into entirely new substances with different properties
ex: burning, rusting, decomposing, etc.
Law of Conservation of Energy
energy cannot be created nor destroyed in a chemical or physical change
Coulomb's Law
opposite charges (+ and -) attract
like charges (- and -) repel that are closer together and higher in magnitude will be the most attracted
entropy
a measure of disorder or chaos in a sample of matter
Second Law of Thermodynamics
systems in nature tend to go to a state of lower energy AND higher entropy (disorder)
THIS SET IS OFTEN IN FOLDERS WITH...