Download Elements, Compounds and Mixtures.

Warm-Up: 2/4
Classifying Elements
• Head a sheet of paper and title it: Elements,
Compounds, and Mixtures Notes
• Science Binder page 32
• Make a subheading (smaller title under the
main title) – Warm-Up: 2/3 Classifying
Elements
• Write a short paragraph explaining what
makes something an element. Include
examples.
Elements, Compounds and
Mixtures Notes
Science Binder p. 32
Classification of Substances
•
•
•
•
Elements
Molecules
Compounds
Mixtures
Elements
• Elements are
substances
made up of
only one type
of atom.
• Example 
Hydrogen,
Gold.
Elements
• Pure substance that cannot be separated into
simpler substances by physical or chemical
means.
– Pure substance- a substance in which there is
only one type of particle (atom or molecule)
Periodic Table of Elements
Molecule
• A molecule is
made up of two
or more atoms
chemically
bonded.
• Atoms can be
the same or
different!
Compounds
• Compounds are pure substances made up
of two or more different types of atoms
chemically bonded.
Properties of Compounds
• When a compound is formed during a
chemical reaction its properties differ from
those of the elements it is made of.
• Example: Water is made from hydrogen
and oxygen.
Hydrogen  flammable gas
Oxygen  colorless gas.
Compounds
• Represented by chemical formulas with two
or more chemical symbols (each capital
letter = a new chemical symbol/element)
• NaCl = sodium chloride (table salt)
• H2O2 = hydrogen peroxide
• C6H12O6 = glucose (sugar plants make from
photosynthesis)
Chemical Formulas
• subscript- small number located at the
bottom right of a chemical symbol, and
gives the number of atoms for the element
in that molecule
Mixtures
• A mixture consists of two or more different
substances mingled together but not
chemically combined.
• Examples:
Sea – water and salt
Air – nitrogen, oxygen …
Soil – sand, clay, humus …
Compare
mixtures and
Compounds.
Mixture
Compound
The amounts of the substances
in the mixture can vary.
The elements in a compound are
always present in the same fixed
proportion.
A mixture contains two or more
substances
A compound is a single
substance.
The properties of a mixture are The properties of a compound
similar to those of the substances are different to those of the
in a mixture.
elements which reacted to form
it.
There are practically no energy Heat is usually given out or
changes when a mixture is made taken in when a compound is
formed.
It is usually easy to separate the
components of a mixture.
It is usually difficult to separate
the components of a compound.
iron particles
Key:
one iron particle
strong bonds
between iron particles
iron particles
held together
by strong bonds
iron particles
iron particles are attracted
to a magnet
iron particles
diagram
sulfur particles
Key:
one sulfur particle
strong bonds between sulfur
particles
sulfur particles
held together
by strong bonds
sulfur particles
sulfur particles are not attracted
to a magnet
sulfur particles
diagram
iron
particles
sulfur particles
What’s this?
A mixture
of iron and sulfur particles
strong bonds
between
iron particles
strong bonds between
sulfur particles
A mixture
of iron and sulfur particles
A magnet attracts the
iron particles
but not the
sulfur particles.
The mixture is separated
mixture diagram
What’s this?
A compound between
iron and sulfur particles
one iron particle
one sulfur particle
strong bonds between
iron and sulfur particles
A compound between
iron and sulfur particles
strong bonds
between
iron and sulfur
particles
The magnet cannot
separate iron and sulfur
particles in a compound
compound diagram
A
B
C
D
E
F
G
H