Transcript Matter Notes

Matter
 Matter is anything that has volume & mass (including
gasses).
 Things that are not made of matter include fire, light,
gravity, sound, and heat.
All matter is classified as a pure substance
or a mixture based on its composition.
What qualifies something as a pure substance?
 A pure substance has a fixed composition.
 Pure substances are made of a single repeating particleeither an element or a molecule- with nothing else
mixed in.
 Pure substances are either compounds or elements.

They cannot be separated into its components by any physical
processes
What Classifies something as an element?
 An element is a pure substance that cannot be broken
down into simpler, stable substances and is made of
one type of atom.
 There are over 100 elements, all listed on the periodic
table.
 An atom is the smallest unit of an element that
maintains the chemical identity of that element.
What classifies something as a compound?
 A compound is a substance that can be broken down
into simple stable substances through chemical
reactions.
 A molecule is the smallest unit of an compound made
from two or more bonded atoms in a fixed composition.
 The composition of a compound is represented by a
chemical formula.
 Compounds are held together by chemical bonds
How are elements different from compounds?
 Elements are composed of only one type of atom
 Ex. Si, O2
 They usually do not have a chemical bond, unless the element
is diatomic, which means it only exists in nature as a pair
 Compounds are composed of more than one type of
atom
 Ex. SiO2
 They must have at least one chemical bond
How do the properties of elements change when
they become compounds?
 The properties of compounds are quite different from
those of their component elements.

When the elements sodium and chlorine combine chemically
to form sodium chloride, there is a change in composition and
a change in properties.
 Sodium is a soft gray metal that is explosive when placed in
water
 Chlorine is a pale yellow poisonous gas.
 Sodium chloride (commonly known as table salt) is a white
solid.
What qualifies something as a mixture?
 A mixture is a blend of two or more kinds of matter,
each of which retains its own identity and properties.
 mixed together physically
 can usually be separated physically
 composition is not uniform
 has no chemical formula
Types of Mixtures
 Homogeneous mixtures are called solutions
 uniform in composition (salt-water solution)
 does not look like a mixture
 Heterogeneous mixtures
 not uniform throughout (sand-water mixture)
 the mixtures components are visible
Homogeneous vs. Heterogeneous
Solution
 a homogeneous mixture
 can be physically separated
 composed of solutes and solvents
the substance in the smallest
amount and the one that
dissolves in the solvent
Iced Tea Mix
(solute)
the substance in the larger
amount that dissolves the
solute
Iced Tea
(solution)
Water
(solvent)
 Water is considered the universal solvent as it is
the solvent used to sustain all life
Solutes Change Solvents
 The amount of solute in a solution determines how
much the physical properties of the solvent are
changed
 Examples:
Lowering the Freezing Point
The freezing point of a liquid solvent
decreases when a solute is dissolved in it.
Ex. Pure water freezes at 00C, but when salt is
dissolved in it, the freezing point is lowered.
This is why people use salt to melt ice.
Raising the Boiling Point
The boiling point of a solution is higher
than the boiling point of the solvent.
Therefore, a solution can remain a liquid at
a higher temperature than its pure solvent.
Ex. The boiling point of pure water is 1000C,
but when salt is dissolved in it, the boiling
point is higher. This is why it takes salt water
longer to boil than fresh water.
Concentration
 the amount of solute dissolved in a solvent at
a given temperature
•described as dilute if it has
a low concentration of
solute
•described as saturated if it
has a high concentration of
solute
•described as supersaturated if
contains more dissolved solute
than normally possible
Solubility
 The ability of a solute to be able to dissolve
in a solution
 The more soluble a substance is, the greater
the concentration the solution is capable of
having
 Influenced by:
Temperature
Pressure
Solids increased temperature causes
them to be more soluble and vice versa
Solids increased pressure has no
effect on solubility
Gases increased temperature causes
them to be less soluble and vice versa
Gases increased pressure causes them
to be more soluble and vice versa
Ex. Iced Coffee
Ex. Soda, “The Bends”