accuracy – the degree of closeness of measurements of a quantity to that quantity’s true value. ...
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Transcript of accuracy – the degree of closeness of measurements of a quantity to that quantity’s true value. ...
accuracy – the degree of closeness of measurements of a quantity to that quantity’s true value.
buoyancy - the tendency or capacity to remain afloat in a liquid or rise in air or gas colloid – heterogeneous mixture with small particles that hang in the mixture compressibility – the ability to move (or squeeze) particles closer together dimensional analysis – a tool to find relationships between quantities using their
dimensions, or units extensive property – properties not inherent to matter itself, and dependent on the
amount of matter present heterogeneous mixture – a mixture of pure substances that is not the same throughout homogeneous mixture – a mixture of pure substances that is the same throughout intensive property – properties inherent to matter itself, and independent of the amount
of matter present precision – the degree which repeated measurements show the same results. scientific notation – a way of writing numbers that are too large or small to use
conventional decimal notation significant figures (sig. figs) – digits in a number that carry meaning contributing to its
precision suspension – heterogeneous mixture with large particles that settle to the bottom. Tyndall effect – light scattering by particles in a colloid viscosity – the measure of a resistance of fluid to flow; “thickness” of a liquid
All matter shares two specific characteristics All matter has mass All matter takes up space
All matter takes one of two basic forms Pure Substance – element or compound Mixture – homogeneous or heterogeneous
• Elements• Matter consisting only of atoms of the same
element
• Compounds• Matter consisting of atoms of different
elements chemically bonded to each other
Homogeneous Mixture
Heterogeneous Mixture
Separation of Mixtures – All mixtures are created by a physical process of mixing and can also be separated by some physical means
A mixture of pure elements that is the same throughout
All samples taken will provide the same proportion of pure substances within that mixture
Also known as a solution
A mixture of pure elements that is not the same throughout
Proportions of pure substances within the mixture are not the same in all samples
Includes colloids and suspensionsColloid – Heterogeneous mixture with small
particles that hang in mixtureSuspension – Heterogeneous mixture with large
particles that settle
Compounds Mixtures
All matter has one chemical structure
Matter has at least two pure substances
Making a compound involves a chemical process of combining elements
Making a mixture involves a physical process of combining elements and compounds
Separating a compound into elements involves a chemical process
Separating a mixture into pure substances involves one or more physical processes
Has a definite proportion by mass
The proportion of pure substances is variable
Pure SubstancesElements cannot be separated.
Compounds can only be separated through some form of chemical reaction.
MixturesAll mixtures are created by a physical process of mixing and can also be separated by physical means
Skimming – Using an instrument to remove floating material from a mixture
Decanting – Pouring off liquid to separate it from solid material at the bottom of the container
Filtering – Using a filter to separate material based on the size of particles
Distillation – Using heat to remove liquid from a mixture leaving behind solid material (evaporation) or a liquid with a very different boiling point (fractional distillation)
Magnetism – Using a magnet to separate magnetic substances from non-magnetic substances
Centrifuging – Using rotational motion to separate substances by mass
All matter can be described through a combination of characteristics called properties
There are two categories of propertiesPhysicalChemical
Descriptions of properties Intensive properties – properties inherent to the
matter itself independent of the amount of the matterExtensive properties – properties not inherent to
matter itself and dependent on the amount of matter present
A combination of intensive and extensive properties that can be observed without changing the substance itself
Describe the size, shape, appearance, amount, and physical attributes of the matter
Examples: Intensive– state of matter, melting point, boiling point,
density, color, crystalline structure, conductivity, malleability, ductility
Extensive– mass, volume, shape, texture, colligative properties
Intensive physical property of matter
States of matter:Solid
Liquid
Gas
Plasma – not discussed in this class
Particles are tightly packed
Particles can only vibrate in place
Rigid form of matter
Definite shape and volume
Generally the most dense state of matter
Least compressible
Particles are close together
Particles flow freely past each other
Definite in volume, but not in shape (takes the shape of its container)
Generally less dense than solids, more dense than gas
Much less compressible than gas, slightly more compressible than solid
Particles fly apart
Particles fully occupy the volume of the container
No definite shape and no definite volume
Generally the least dense state of matter
Most compressible
The ability to move (squeeze) particles closer together
The closer the particles are before attempting to move them, the less the particles can move Examples: particles of solids are very close
together and cannot move nearly as far as particles of gases that start out much further apart
Any change in matter that is accomplished without changing the substance into a new substance
The substances present before and after the change are of the same chemical structure as they were before the change
Includes any change to the size, shape, or state of the matter changed
Do not get confused by the words ice, water, and steam – melting, freezing, condensing, or evaporating water are physical changes – the chemical composition is not changed
Intensive physical property that measures of how tightly packed matter is
Directly related to the mass of matter and inversely related to the volume (both of which are extensive properties)
Formula: Density = Mass / Volume
Mass is measured in grams and volume for solids and liquids are generally measured in cm3 (mL) or L (Liters)
All chemical properties are intensive
Chemical properties can only be observed by changing the matter itself
Examples: reactivity, combustibility, ionization energies, electronegativity, electron affinity, corrosiveness