Classifying Matter:
Elements, Compounds, and
Mixtures
Pure Substance
 A sample of matter that has definite chemical and
physical properties.
H
Oxygen
•
•
gas
sustains combustion
O
Hydrogen
•
•
gas
explosive
H
Water
•
•
•
liquid
non-explosive
does not sustain
combustion (burning)
H2O
H
O
Element
 A pure substance that cannot be separated into simpler
substances by physical or chemical means. It is made of
just one type of atom.
o An atom is the smallest particle in an element that still has the
physical and chemical properties of the element.
Elements and Atoms
 An atom is the smallest particle in an element that still has the
physical and chemical properties of the element.
Elements and Atoms
 An atom is the smallest particle in an element that still has the
physical and chemical properties of the element.
Hydrogen
Helium
Sodium
Lithium
Elements and Atoms
 An atom is the smallest particle in an element that still has the
physical and chemical properties of the element.
Hydrogen
Helium
Sodium
Lithium
Elements and Atoms
 An atom is the smallest particle in an element that still has the
physical and chemical properties of the element.
Hydrogen
Helium
Sodium
Lithium
Elements and Atoms
 An atom is the smallest particle in an element that still has the
physical and chemical properties of the element.
Hydrogen
Helium
Sodium
Lithium
Elements and Atoms
 An atom is the smallest particle in an element that still has the
physical and chemical properties of the element.
Hydrogen
Helium
Sodium
Lithium
Compound
• A compound is a pure substance composed of two or more
different elements joined by chemical bonds.
o Made of elements in a specific ratio that is always the same
o Has a chemical formula
o Can only be separated by chemical means,
not physically
o A molecule is two or more atoms combined chemically
o A molecule is the smallest particle in a compound that still has
the physical and chemical properties of the compound.
Molecules
• A molecule is two or more atoms combined chemically
• A chemical formula identifies the molecule
Molecules
• A molecule is two or more atoms combined chemically
• A chemical formula identifies the molecule
• A molecule could be made up of…
…two or three identical atoms of the same element
O2 Oxygen
O3 Ozone
H2 Hydrogen
…two or more atoms of different elements
H2O2 Hydrogen peroxide
C6H12O6 Glucose (sugar)
Molecules
• A molecule is two or more atoms combined chemically
• A chemical formula identifies the molecule
• A molecule could be made up of…
…two or three identical atoms of the same element
…two or more atoms of different elements
• A compound forms when atoms of two or more different
elements combine chemically, or through a chemical change
Molecules
• A molecule is two or more atoms combined chemically
• A chemical formula identifies the molecule
• A molecule could be made up of…
…two or three identical atoms of the same element
…two or more atoms of different elements
• A compound forms when atoms of two or more different
elements combine chemically, or through a chemical change
Molecules
• A molecule is two or more atoms combined chemically
• A chemical formula identifies the molecule
• A molecule could be made up of…
…two or three identical atoms of the same element
…two or more atoms of different elements
• A compound forms when atoms of two or more different
elements combine chemically, or through a chemical change
Molecules
• A molecule is two or more atoms combined chemically
• A chemical formula identifies the molecule
• A molecule could be made up of…
…two or three identical atoms of the same element
…two or more atoms of different elements
• A compound forms when atoms of two or more different
elements combine chemically, or through a chemical change
• When a compound forms, a new substance with different
properties than the original substances is formed
=
Soft, shiny metal (solid)
Reacts w/ water (explodes)
Table salt
Greenish gas
Reacts with body tissue (poisons)
Mixture
 A mixture is a combination of two or more pure
substances that are not chemically but rather physically
combined.
o Substances held together by physical forces, not chemical
o No chemical change takes place but rather a physical change
o Each item retains its properties in the mixture
o They can be separated physically
•solid
•white
•salty
•liquid
•“clear”
•“tasteless”
Salty water
liquid & “colorless” like water
salty and “whitish” like salt
How can they be
separated?
Mixtures vs. Compounds
http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/elements_com_mix_6.shtml
Only one type of atom
Only one type of atom
Only one type of atom
Two types of atoms
chemically combined
Only one type of atom
Two types of atoms
chemically combined
Only one type of atom
Two types of atoms
chemically combined
Only one type of atom
Two types of atoms
chemically combined
Only one type of atom
Two types of atoms
chemically combined
Two or more different
types of particles (atoms
and/or molecules)
physically combined and
unevenly distributed
Only one type of atom
Two types of atoms
chemically combined
Two or more different
types of particles (atoms
and/or molecules)
physically combined and
unevenly distributed
Only one type of atom
Two types of atoms
chemically combined
Two or more different
types of particles (atoms
and/or molecules)
physically combined and
unevenly distributed
Two or more different
types of particles (atoms
and/or molecules)
physically combined and
evenly distributed
Can you identify the following?
You will be shown a series of slides. Tell if each photo represents an
item composed of an element, compound, or mixture.
Review:
 An element contains just one type of atom.
 A compound contains two or more different atoms joined
together chemically. Its properties are different from those
of its components.
 A mixture contains two or more different substances that
are only physically together. It can contain both elements
and compounds. Its properties are a combination of the
properties of its components.
Element, Compound, or Mixture?
Rocks
Element, Compound, or Mixture?
Rocks
Element, Compound, or Mixture?
Copper
Element, Compound, or Mixture?
Copper
Element, Compound, or Mixture?
Jelly Beans
Element, Compound, or Mixture?
Jelly Beans
Element, Compound, or Mixture?
Table Sugar
Element, Compound, or Mixture?
Table Sugar
Element, Compound, or Mixture?
Diamond
Element, Compound, or Mixture?
Diamond
Element, Compound, or Mixture?
Tea
Element, Compound, or Mixture?
Tea
Element, Compound, or Mixture?
Salt
Element, Compound, or Mixture?
Salt
Element, Compound, or Mixture?
Neon Gas
Element, Compound, or Mixture?
Neon Gas
Element, Compound, or Mixture?
Salad
Element, Compound, or Mixture?
Salad
Element, Compound, or Mixture?
Pure Water
Element, Compound, or Mixture?
Pure Water
Element, Compound, or Mixture?
Aluminum
Element, Compound, or Mixture?
Aluminum
Element, Compound, or Mixture?
Lemonade
Element, Compound, or Mixture?
Lemonade
Element, Compound, or Mixture?
Silver
Element, Compound, or Mixture?
Silver
Element, Compound, or Mixture?
Sand
Element, Compound, or Mixture?
Sand
Can you identify the following?
You will be shown another series of slides. Tell if each show an atom
or a molecule.
Atom or Molecule?
CO2
Atom or Molecule?
CO2
Carbon dioxide
Atom or Molecule?
Atom or Molecule?
CH4 methane
Atom or Molecule?
Fe
Atom or Molecule?
Fe
Iron
Atom or Molecule?
Atom or Molecule?
molecules of one type of
atom (same element)
Atom or Molecule?
CO
Atom or Molecule?
CO
Carbon monoxide
Atom or Molecule?
Atom or Molecule?
mixture of atoms (green)
and molecules (purple)
(element & compound)
Atom or Molecule?
Co
Atom or Molecule?
Co
Cobalt
Atom or Molecule?
Atom or Molecule?
Atom or Molecule?
Surprise! It’s Hydrogen!
Atom or Molecule?
N2
Atom or Molecule?
N2
Nitrogen
Atom or Molecule?
C6H12O6
Atom or Molecule?
C6H12O6
Simple sugar:
glucose, fructose,
sucrose
Atom or Molecule?
Atom or Molecule?
mixture of two types of
molecules (two different
elements)
Atom or Molecule?
Hg
Atom or Molecule?
Hg
Mercury
Atom or Molecule?
Atom or Molecule?
Nitrogen
Atom or Molecule?
Fe2O3
Atom or Molecule?
Fe2O3
Iron oxide - rust
Atom or Molecule?
Atom or Molecule?
molecules of water
Atom or Molecule?
O2
Atom or Molecule?
O2
Oxygen
Atom or Molecule?
Atom or Molecule?
mixture of two types of
atoms (two different
elements
Atom or Molecule?
Na
Atom or Molecule?
Na
Sodium
Atom or Molecule?
O3
Atom or Molecule?
O3
Ozone
Atom or Molecule?
Atom or Molecule?
one type of atom
(same element)
Atom or Molecule?
He
Atom or Molecule?
He
Helium
Atom or Molecule?
Atom or Molecule?
DNA
deoxyribonucleic acid
Notes
 Detailed notes are located at:
http://www.middleschoolscience.com/elements-compoundsmixtures-notes-isn.pdf
 Flow Chart:
http://www.middleschoolscience.com/matter-flow-chartisn.pdf