Groups of atoms held together in a characteristic pattern and proportion
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Chemical bonds
What holds atoms together
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Sublimation
Solid to gas
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Deposition
Gas to solid
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Energy
The ability to do work
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Work (w)
The exertion of a force (F) through a distance (d)
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Equation for work
w = F x d
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Heat
Energy transfer where energy flows from a warm object to a cooler one
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Chemical Reactions
One or more substances converted into one or more different substances
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Potential Energy (PE)
Energy stored in an object because of its position or composition
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Kinetic Energy (KE)
Energy of motion
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Law of Conservation of Energy
Energy cannot be created or destroyed, only converted
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Kinetic Energy equation
KD = 1/2mu^2
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Symbol for speed
u
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Pure Substance
matter that cannot be separated into simpler matter by a physical process
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Physical Process
a transformation of a sample of matter, such as a change in its physical state, that does not alter the chemical identity of any substance in the sample
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Element
A pure substance that cannot be separated into simpler substances by any chemical process
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Compound
A pure substance that is composed of two or more elements linked together in fixed proportions and that can be broken down into those elements by some chemical process
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Chemical Formula
a notation for representing the elemental composition of a pure substance using the symbols of the elements; subscripts indicate the relative number of atoms of each element in the substance
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Law of Constant Composition
the principle that all samples of a particular compound always contain the same elements combined in the same proportions
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Mixture
a combination of pure substance in variable proportions in which the individual substances retain their chemical identities and can be separated from one another by a physical means
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Homogeneous Mixture
a mixture in which the components are distributed uniformly throughout and have no visible boundaries or regions
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Solution
another name for a homogeneous mixture
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Heterogeneous Mixture
a mixture in which the components are not distributed uniformly, so that the mixture contains distinct regions of different compositions
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Immiscible Liquids
combinations of liquids that are incapable of mixing with, or dissolving in, each other
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Distillation
a process using evaporation and condensation to separate a mixture of substances with different volatilities
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Volatility
a measure of how readily a substance vaporizes
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Filtration
a process for separating solid particles from a liquid or gaseous sample by passing the sample through a porous material that retains the solid particles
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Chromatography
a process involving stationary and mobile phases for separating a mixture of substances based on their different affinities for the two types of phases
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Intensive Property
a property that is independent of the amount of substance present (density, hardness)
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Extensive Property
a property that varies with the amount of substance present (mass, volume)
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Physical Property
a property of a substance that can be observed without changing the substance into another substance
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Density (d)
the ratio of the mass (m) of an object to its volume (V) d = m/V
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Chemical Property
a property of a substance that can be observed only by reacting the substance chemically to form another substance
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Scientific Method
an approach to acquiring knowledge based on observation of phenomena, development of a testable hypothesis, and additional experiments that test the validity of the hypothesis
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Scientific Law
a concise and generally applicable statement of a fundamental scientific principle
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Law of Definite Proportions
compounds always contain the same proportions of their component elements equivalent to the Law of Constant Composition
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Scientific Theory
a general explanation of widely observed phenomena that has been extensively tested
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Hypothesis
a tentative and testable explanation for an observation or a series of observations
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Law of Multiple Proportions
when two masses of one element react with a given mass of another element to form two different compounds, the two masses of the first element have a ratio of two small numbers
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Molecular Formula
a chemical formula that shows how many atoms of each element are in one molecule of a pure substance
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Structural Formula
a representation of a molecule that uses short lines between the symbols of elements to show chemical bonds between atoms
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Ball-and-Stick Models
Show bond angles, but make the atoms appear far apart
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Space-filling models
More accurately show how the atoms are arranged in a molecule and its overall 3D shape, but it can be hard to see all the atoms and angles
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Meter (m)
the standard unit of length; equivalent to 39.37 inches
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Joule (J)
the SI unit of energy, equivalent to 1 kg(m/s)^2
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pico
10^-12
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nano
10^-9
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micro
10^-6
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milli
10^-3
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centi
10^-2
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deci
10^-1
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deka
10^1
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hecto
10^2
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kilo
10^3
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Precision
the extent to which repeated measurements of the same variable agree
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Accuracy
agreement between an experimental value and the true value
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Significant Figures
all the certain digits in a measured value plus one estimated digit. The greater the number of sig figs, the greater the certainty with which the value is known
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Absolute Zero
zero point on kelvin temperature scale; theoretically the lowest temperature possible. -273 °C or -459 °F
Studied by 3 people
