Unit 1 Flashcards
A heterogeneous mixture
a mixture in which the composition is not uniform throughout the mixture.
homogeneous
A homogeneous mixture is a mixture in which the composition is uniform throughout the mixture
compound
a compound is a substance made up of two or more different chemical elements combined in a fixed ratio
element
a pure substance that cannot be broken down by any physical or chemical means into simpler substances
chemistry
in this science we study matter and the changes it undergoes
scientific method
the scientific method is simply a systematic approach to solving problems
Matter
we define matter as anything that has mass and takes up space
matter(atoms)
-atoms are the building blocks of matter
-each element is made of the same kind of atom
-a compound is made of two or more different kinds of elements
Classification of matter (particle theory of matter)
-all matter is made up of tiny particles
-each pure substance has its own kind of particle which is different from the particles of other pure substances
-particles attract each other
-particles are always moving
-particles at a higher temperature move faster,on average,than particles at a lower temperature
what are the 3 states of matter
gas, liquid, crystalline solid (soild)
gas
Total disorder, much empty space ; particles have complete freedom of motion particles far apart
liquid
disorder, particles or clusters of particles are free to move relative to each other, particles close together
crystalline solid
ordered arrangement; particles are essentailly in fixed positions;particles close together
classification of matter
matter can be classified grouped based on different characteristics
Element
- pure substance
- cannot be broken down into simpler parts by chemical or physical methods
- eg. helium(He), oxygen(O),hydrogen (H)
Compound
- pure substances
- made of two or more different elements that are chemically combined
Mixture
- matter that contains **more than one **kind of particle
- eg. salt water=water particles (H2O) + salt ( NaCI) particles
- eg. air+oxygen(02)+ nitrogen(N₂) + carbon dioxide(CO₂) + other gases
- e.g. vinegar = acetic acid (CH3COOH(aq)) +
water particles (H2O)
info about mixtures
mixtures can be homogeneous or heterogeneous.
* A** homogeneous mixture** is one where the
components that make up the mixture are
uniformly distributed throughout the mixture.
* The mixture looks the same throughout.
* Examples: air, blood, saturated sugar water
info about mixtures part 2
- A heterogeneous mixture is a mixture where the
components of the mixture are not uniform or
have localized regions with different properties. - The mixture does not look the same throughout.
- Examples: sand, oil and water, granola, pizza
- The components of a mixture are physically
combined. As a result, a mixture can be separated
by physical methods.
Filtration
In filtration solid
substances are
separated from liquids
and solutions.
eg. a filter separating coffee grounds from the brewed coffee that passes through
Distillation
Distillation uses
differences in the
boiling points of
substances to
separate a
homogeneous
mixture into its
components.
eg. an apparatus shows how a liquid with a lower boiling point than other components in a mixture it is vaporized ,condensed and collected in a beaker
What are the advantages elements and compounds have on our society
making our lives healthier and safer and enabling us to accomplish
things that were once unimaginable.
What are the disadvantages elements and compounds have on our society
negative consequences, such as the
release of pollutants into the environment.
In many cases, humans need to
determine whether the advantages
outweigh the disadvantages.
physical property
is a characteristic of a substance that can be
observed and measured without changing the identity of the substance.
The physical properties of
materials play a significant role
in determining practical uses for
these substances.
Qualitative physical properties
can be observed and described
without detailed measurement.
Qualitative properties are:
colour, odour,state,texture, lustre and malleability
Quantitative physical properties
are properties that can be measured
and assigned a particular value
Quanititative physical properties are:
viscosity, melting point,boiling point, solubility, hardness, conductivity and density
What are the 2 types of properties
Intensive and Extensive Properties
Intensive properties
Are independent of the amount of the substance that is present.
eg.Density, boiling point, color, etc.
Extensive properties
Depend upon the amount of the substance present.
eg. mass, volume, energy,ect.
states of matter
The specific temperature at which an element or compound changes
state is a characteristic physical property illustrated by the diagram
below.
What are the changes of state
melting,solidification,evaporation,condensation,sublimation and deposition
melting
changing from a solid to a liquid (ice turning to water)
solidification
changing from a liquid to a solid (water freezing)
evaporation
changing from a liquid to a gas (a puddle disappears on
a hot day)
condensation
changing from a gas to a liquid (drops of water
forming on a cold glass in the summer)
sublimation
changing from a solid to a gas (dry ice disappearing)
deposition
changing from a gas to a solid (the formation of frost)
solubility
is the maximum quantity of a substance (solute) that can
dissolve in a given amount of solvent at a particular temperature and
pressure. Solubility is measured in units of mass of solute per mass of
solvent or mass of solute per volume of solvent.
Solutions with water as the solvent are called aqueous solutions.
solubility and the environment
*Solubility in fat is an especially important property for some
chemicals. For this reason, toxic substances such as DDT can build up
in the fat of animals. This bioaccumulation leads to the
biomagnification of the toxin at higher levels of the food chain.
Hardness
The hardness of a substance refers to its ability to be scratched.
Hardness is measured using Moh’s scale (a scale from 1 to 10, with 10
being hardest). Harder substances will scratch softer materials that are
lower on the scale. At 10 on Moh’s scale, diamond is the hardest
natural material on Earth. Drill bits use diamonds to cut through other
slightly less hard substances.
Density
is the ratio of the mass of a substance to the volume it
occupies. The density of a substance can be calculated by using the
following formula: D= m / v
Density of a material
The density of a material determines if it
will float on top of another substance.
Less dense substances, such as the
bunker oil shown in the picture on the
left, float on the more dense salt water.
An understanding of the densities of
substances can be used when attempting
to separate them.
water’s unique physical properties
- is called the “universal
solvent” - is more dense as a liquid
than as a solid (ice floats on
water) - is the only natural substance
that exists as a solid, liquid,
and gas on Earth - can absorb a lot of heat
before it gets hot. It has a high
specific heat capacity.
