20 terms

# Modern Chemistry Chapter 2 Measurements and Calculations Vocabulary

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scientific method
a series of steps followed to solve problems, including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions
system
a set of particles or interacting components considered to be a distinct physical entity for the purpose of study
hypothesis
an explanation that is based on prior scientific research or observations and that can be tested
model
a pattern, plan, representation, or description designed to show the structure or workings of an object, system, or concept
theory
an explanation for some phenomenon that is based on observation, experimentation, and reasoning
quantity
something that has magnitude, size, or amount
SI
Le Systéme International d'Unités, or the International System of Units, which is the measurement system that is accepted worldwide
weight
a measure of the gravitational force exerted on an object; its value can change with the location of the object in the universe
derived unit
unit of measure that is a combination of other measurements
volume
a measure of the size of a body or region in three-dimensional space
density
the ratio of the mass of a substance to the volume of a substance; often expressed as grams per cubic centimeter for solids and liquids and as grams per liter for gases
conversion factor
a ratio that is derived from the equality of two different units and that can be used to convert from one unit to the other
dimensional analysis
a mathematical technique for studying dimensions of physical quantities
accuracy
a description of how close a measurement is to the true value of the quantity measured
precision
the exactness of a measurement
percentage error
a figure that is calculated by subtracting the accepted value from the experimental value, dividing the difference by the accepted value, and then multiply it by 100
significant figures
a prescribed decimal place that determines the amount of rounding off to be done based on the precision of the measurement
scientific notation
a method of expressing a quantity as a number multiplied by 10 to the appropriate power
directly proportional
the relationship between two variables whose ration is a constant value
inversely proportional
the relationship between two variables whose product is constant