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32 terms

chemistry test 1

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scientific method
observation, formation of hypothesis, experimentation, development of theory
hypothesis
scientifically correct name for an educated guess
law
a summary of large amounts of data and results in words or equations
theory
framework of organization of scientific knowledge
models
pictures for invisible process
chemistry
the study of matter and the changes that it undergoes (energy changes)
matter
anything that has mass and occupies space
energy
capacity for doing work
chemical change
how a substance reacts with other substances
physical change
properties that can be specified without reference to other substances
extensive
dependent on the amount of substance
ex: mass, volume
intensive
independent of the amount of substance
ex: density, melting/boiling points
element
matter that is composed of only one type of atom; cannot be converted to simpler substance by ordinary chemical means
atom
smallest particle of an element that retains the chemical characteristics of that element
compound
2 or more elements combined in a fixed and well defined ratio by mass
mixture
2 or more elements and/or compounds combined in a variable ratio by mass; can be homogeneous or heterogeneous
homogeneous
uniform in composition with no visible boundaries separating different regions
heterogeneous
noniniform in composition with at least 2 distinct regions and 1 visible boundary
density
the mass of an object divided by its volume;measure of the amount of matter per unit volume
kinetic energy
energy due to motion
potential energy
stored energy due to position of an object
three laws of chemistry
law of conservation of mass; law of definite proportions; law of multiple proportions
law of conservation of mass
matter is neither created nor destroyed in ordinary chemical reactions
law of definite proportions
compounds contain elements in certain definite proportions and in no other combinations
law of multiple proportions
elements may combine in more than one set of proportions but each set corresponds to a different compound
atomic theory 1
atoms are fundamental particles of varying sizes and shapes
atomic theory 2
atoms of different elements are distinct in size and shape
atomic theory 3
real substances are mixtures of atoms of different elements in different proportions
atomic theory 4
one substance can be changed into another by simply changing the proportions of the element
electrolyte
A compound that conducts electricity when melted or dissolved in water
electrodes
A device inserted into an electrochemical cell at which oxidation or reduction occurs
electrolysis electrolysis
Causing a chemical reaction by means of electricity