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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

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