Download What is a mixture?

What are Elements?
• An element is a pure substance that cannot be
separated or broken down into simpler
substances by physical or chemical means.
• What are examples of elements?
– Anything that is on the Periodic Table of Elements.
– Examples: Gold (Au), Silicon (Si), Neon (Ne), Silver
(Ag), sulfur (S)
S
Au
Ag
Fe
The Periodic Table of Elements
Everything that is on this
table is an element. If it isn’t
on this table, it isn’t an
element!
Pure Substances
• Pure substances are substances in which there
is only one type of particle.
• These particles are called atoms.
• The only two things that are pure substances
are:
1. Elements
2. Compounds
Identifying Elements
• Elements are categorized by unique properties
on the Periodic Table.
• They are arranged in order by their number of
protons. (More on this later!)
• Each element has unique properties like
melting point, boiling point, and whether it is
metal, nonmetal or metalloid.
What are compounds?
• A compound is a pure substance composed of
two or more elements chemically combined.
• This means they were formed by a chemical
reaction.
Elements
Compounds
Familiar Compounds
Compound
Elements Combined
Formula
Table salt
Sodium and Chlorine
NaCl
Water
Hydrogen and Oxygen
H2O
Vinegar
Hydrogen, Carbon, and
Oxygen
Carbon and Oxygen
C2H4O2
Sodium, Hydrogen,
Carbon and Oxygen
NaCHO3
Carbon
dioxide
Baking soda
CO2
Forming a Compound
• Compounds are formed by combining two or
more elements.
– Elements are “stuck together” by chemical bonds
– When this happens, new properties are formed;
the elements lose their original properties.
– You end up with one new thing!
ELEMENTS MAKE
COMPOUNDS!!
Example: Formation of NaCl
+
Sodium is a soft,
silvery white metal
that reacts violently
with water.
Chlorine is a
poisonous,
greenish-yellow gas.
Sodium Chloride,
or table salt, is a
white solid. It
dissolves easily in
water and is safe to
eat.
**Compounds have properties that differ
from those of the elements that form it!**
How are compounds separated?
• Compounds are broken apart by breaking
chemical bonds.
– You separate them by forcing another chemical
reaction to happen
– CHEMICAL CHANGE!!!!
– Add heat, electricity, another compound or
element as a chemical reaction
• Remember compounds are specific recipes!
They have a fixed ratio!
Breaking Chemical Bonds
What is a mixture?
• A mixture is when 2 or more substances are
combined but do not chemically react.
• THE SUBSTANCES KEEP THEIR OWN
PROPERITES!!
• We say that we MIX to form them.
Examples of Mixtures
1.
2.
3.
4.
Iced tea powder and water
Granite
Milk
Oil and vinegar
3 Properties of a Mixture
1. It is NOT a chemical change
2. It can be separated by physical means
3. Ratio of each substance does NOT matter
Separation of a Mixture
1.
2.
3.
4.
5.
Pick apart or straining
Evaporation
Filter
Centrifuge
Distillation (boiling the solvent to separate it
from the solute)
6. Magnetism (like iron)
Separating a mixture is a
PHYSICAL CHANGE because
there are no chemical
reactions or changes - parts
keep their properties!!
Types of Mixtures
Homogeneous
(Homo = same)
The mixture
appears to be the
SAME throughout
Heterogeneous
(Hetero = different)
The mixture appears
to be DIFFERENT
throughout
Examples
HOMOGENEOUS
Milk
Stainless steel
Oil
Brass (Cu + Zn)
HETEROGENEOUS
Oil & vinegar
Concrete
Soil
Pizza, Cereal
All matter
YES
NO
Can it be separated by physical means?
Mixtures
Pure substances
Is the composition
uniform?
YES:
Can it be decomposed by
ordinary chemical
means?
NO:
Homogeneous
Mixtures
Heterogeneous
Mixtures
(air, sugar in
water, stainless
steel)
(granite, wood,
blood)
SAME
THROUGHOUT
DIFFERENT
THROUGHOUT
YES:
NO:
Compounds
Elements
(water, sodium
chloride,
quartz)
(gold, aluminum,
oxygen, chlorine)