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Atoms
Tiny building blocks
Molecules
Groups of atoms held together in a characteristic pattern and proportion
Chemical bonds
What holds atoms together
Sublimation
Solid to gas
Deposition
Gas to solid
Energy
The ability to do work
Matter
Everything in the universe that has mass (m)
Solid
Definite volume and shape
Liquid
Definite volume but not a definite shape
Gas (vapor)
Neither definite volume or shape
Work (w)
The exertion of a force (F) through a distance (d)
Equation for work
w = F x d
Heat
Energy transfer where energy flows from a warm object to a cooler one
Chemical Reactions
One or more substances converted into one or more different substances
Potential Energy (PE)
Energy stored in an object because of its position or composition
Kinetic Energy (KE)
Energy of motion
Law of Conservation of Energy
Energy cannot be created or destroyed, only converted
Kinetic Energy equation
KD = 1/2mu^2
Symbol for speed
u
Pure Substance
matter that cannot be separated into simpler matter by a physical process
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
Element
A pure substance that cannot be separated into simpler substances by any chemical process
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
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
Law of Constant Composition
the principle that all samples of a particular compound always contain the same elements combined in the same proportions
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
Homogeneous Mixture
a mixture in which the components are distributed uniformly throughout and have no visible boundaries or regions
Solution
another name for a homogeneous mixture
Heterogeneous Mixture
a mixture in which the components are not distributed uniformly, so that the mixture contains distinct regions of different compositions
Immiscible Liquids
combinations of liquids that are incapable of mixing with, or dissolving in, each other
Distillation
a process using evaporation and condensation to separate a mixture of substances with different volatilities
Volatility
a measure of how readily a substance vaporizes
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
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
Intensive Property
a property that is independent of the amount of substance present (density, hardness)
Extensive Property
a property that varies with the amount of substance present (mass, volume)
Physical Property
a property of a substance that can be observed without changing the substance into another substance
Density (d)
the ratio of the mass (m) of an object to its volume (V)
d = m/V
Chemical Property
a property of a substance that can be observed only by reacting the substance chemically to form another substance
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
Scientific Law
a concise and generally applicable statement of a fundamental scientific principle
Law of Definite Proportions
compounds always contain the same proportions of their component elements equivalent to the Law of Constant Composition
Scientific Theory
a general explanation of widely observed phenomena that has been extensively tested
Hypothesis
a tentative and testable explanation for an observation or a series of observations
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
Molecular Formula
a chemical formula that shows how many atoms of each element are in one molecule of a pure substance
Structural Formula
a representation of a molecule that uses short lines between the symbols of elements to show chemical bonds between atoms
Ball-and-Stick Models
Show bond angles, but make the atoms appear far apart
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
Meter (m)
the standard unit of length; equivalent to 39.37 inches
Joule (J)
the SI unit of energy, equivalent to 1 kg(m/s)^2
pico
10^-12
nano
10^-9
micro
10^-6
milli
10^-3
centi
10^-2
deci
10^-1
deka
10^1
hecto
10^2
kilo
10^3
Precision
the extent to which repeated measurements of the same variable agree
Accuracy
agreement between an experimental value and the true value
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
Absolute Zero
zero point on kelvin temperature scale; theoretically the lowest temperature possible. -273 °C or -459 °F
0 °C
32 °F or 273 K
Conversion for °F to °C
°C = 5/9(°F-32)
Conversion for °C to K
K = °C + 273.15
