Elements Compounds
• have a unique set of
properties
• components are
protons, neutrons, and
electrons
•have only one type of
particle
• are pure substances
• cannot be separated
into simpler substances
• have a unique set of
properties
• have a unique set of
properties
• components are
elements
• components are
elements, compounds,
or both
• have only one type of
particle
•are pure substances
• can be separated into
simpler substances by
chemical means only
• some are chemically
combined
• combine in a definite
ratio to form different
compounds
•combine into definite
ratios to form a
compound
• are chemically
combined
•found everywhere
Mixtures
• found everywhere
•has two or more
different types of
particles
•not chemically
combined
•not pure substances
•can be separated by
physical means into the
different substances
that form it
• combine in any ratio
Pure Substance is a
substance in which
there is only one
type of particle;
includes elements
and compounds.
Definite Ratio Combinations of
Elements forming Compounds
H2O2
2 atoms of hydrogen to one of
oxygen
2 atoms of hydrogen to 2 of
oxygen
CO2
1 atom of carbon to 2 of oxygen
carbon dioxide
CO
1 atom of carbon to 1 of oxygen
carbon monoxide
H2O
C6H12O6
NaCl
CH2O
6 atoms of carbon, to 12 of
hydrogen, to 6 of oxygen
1 atom of sodium to 1 of
chlorine
1 atom of carbon, to 2 of
hydrogen, to 1 of oxygen
water
hydrogen peroxide
sugar
salt
wood
Element
A pure substance that cannot be separated into simpler
substances by physical or chemical means.
hydrogen
carbon
silicon
ELEMENT
PURE SUBSTANCE
Na
Na
Na
Na
Na
Na
Na
Na
Na
Na
Na
Na
Na
Na
Na
Na
Na
Na
Na
Na
Na
Metals
Metalloids
• shiny
• some are shiny
some are dull
• malleable
• ductile
• good
conductors of
thermal and
electric
energy
• have
reactivity
• some are
malleable and
some are not
• some are ductile
and some are not
•semiconductors
of electric energy
• have reactivity
Nonmetals
• dull
• brittle
• not malleable
• not ductile
• poor
conductors of
thermal and
electric energy
• some have
reactivity
Compound
A pure substance composed of two or more
elements that are chemically combined.
+
Molecule of the Compound
Water
+
hydrogen
Chemically
combined
hydrogen
_
oxygen
Mixture
Mixture
A combination of two or more substances
that are not chemically combined.
Sodium
chloride and
water
molecules
chloride
sodium
+
chloride
sodium
+
COMPOUND WATER
PURE SUBSTANCE
MIXTURE of TWO ELEMENTS and the
COMPOUND WATER
NOT A PURE SUBSTANCE
oxygen
Chemically
combined
O2
Properties of Compounds
• color
•shape
•boiling point
• melting point
• density
• freezing point
• reactivity ( combustible, explosive, and
flammable)
burning wood
CH2O + O2 -----> CO2 + H2O
Mixture
Compound
Element
ELEMENT
PURE SUBSTANCE
COMPOUND
WATER
PURE SUBSTANCE
MIXTURE of TWO
ELEMENTS and the
COMPOUND
WATER
NOT A PURE
SUBSTANCE
Solution
The liquid that
results when
water dissolves
a substance.
The Compound Water
Chemically combined
+
+
H2O
-
Electrons being
shared between
atoms of
hydrogen and
oxygen.
sodium chloride
+
-
-
+
+
-
+ -
+
+
+ - +
+
+ -
NaCl
+
Na ion
Cl ion
sodium
metal
salt
chlorine
+
gas
H is the symbol O is the symbol
of Hydrogen
for Oxygen
H2 O
The subscript
means each
molecule of water
has two atoms of
hydrogen
No subscript
after oxygen
means each
molecule of
water has
only one atom
of oxygen.
The coefficient means
that there are three
molecules of water.
molecule
3 H 2O
Parts of a Chemical Equation
C + O2
yields
or
produces
The compounds
or elements on
the left side of
the arrow are the
starting
materials, or
REACTANTS.
CO2
The new
substance
produced is the
PRODUCT. The
product is placed
to the right of the
arrow.
A plus sign separates
reactants when there is
more than one.
NaOH + HCl
NaCl + H2O
A plus sign separates products
when there is more than one
new substance produced.
In a chemical equation the
number of atoms in the
reactants should always equal
to the number of atoms in the
products.
C + O2
1 atom
carbon
2 atoms
oxygen
=
CO2
1 atom 2 atoms
carbon oxygen
Element
A pure substance that
cannot be separated into
simpler substances by
physical or chemical
means.
Chemically
oxygen combined
O2
Compound
A pure substance
composed of two or
more elements that are
chemically combined.
Molecule of the
Compound Water
+
+
Mixture
A combination of two or
more substances that
are not chemically
combined.
Sodium chloride and water
molecules
chloride
hydrogen
Chemically
combined
_
sodium
+
carbon
silicon