Topic: Classifying Matter
Which of the following is a physical change that
requires energy?
a) H2O (l)  H2(g) + O2 (g)
b) H2O (l)  H2O (s)
c) H2O (s)  H2O (l)
d) H2(g) + O2 (g)  H2O (l)
Matter
Can it be separated by physical methods
NO
YES
Substances
Elements
Compounds
Mixtures
Heterogeneous
Mixtures
Homogeneous
Mixtures
Mixtures  Separated by physical methods
Compounds  Separated by chemical methods
Pure Substance
• Homogenous (uniform throughout)
• Definite composition
• Same characteristic properties regardless of
source
which are pure substances
Element
• Substance that:
• cannot be broken down or
decomposed into simpler
substance
• only 1 kind of atom
• has definite properties
• Formulas have 1 uppercase
letter
Cu
Cu
Cu
Cu
F2
F
F
F
F
Atom
• smallest particle of element that
retains properties of element & can
undergo a chemical rxn
• Atoms can be combined to form
molecules =2 or more total atoms
F
F
F
F
Particle Diagrams








Atoms of a
monatomic (1)
element




Molecules of
a diatomic
(2) element
HH2
These seven elements are always
diatomic
NN2
OO2
FF2
Cl
Cl2
Br
Br2
II2
Element Song
Big Bang Version sung by Sheldon
Compounds
• 2 or more elements chemically
combined in a definite ratio
• Properties are different from
those of elements formed
from
• Only Broken into elements by
chemical decomposition
reaction
• Formulas have 2 or more
uppercase letters
HCl
Cl
H
H
Cl
Cl
H
H2O
O
H
H
O
H
H
2Na + Cl2  2NaCl
Na = atom, element
Atoms or Molecules?
Element or Compound?
Cl2 = molecule, element
NaCl = molecule, compound
Particle Diagrams







 

 








Molecules of a
triatomic (3)
compound
Mixture:
monatomic element,
diatomic element,
triatomic compound
Made of Ions
Na+1Cl-1 = NaCl
Mixtures
• Combo of 2 or more pure
substances (elements + elements) (elements
+ compounds) (compounds + compounds)
• Physically combined not
chemically combined
• Each substance retains its own
identity and properties
Mixtures
• Variable composition
• No unique properties
(Think of sugar and salt mixed together)
• Separated by physical methods
• May be homogeneous or heterogeneous
Types of Mixtures
• Heterogeneous: definite variation in
composition, individual components
visible - scatters light (can’t shine light through)
Oil in water
Granite
Salad
dressing
Colloids
(type of heterogeneous mix.)
• Particles are suspended- they are too small to see
Aerosols: solid or liquid particles in gas
– Ex: Smoke/Fog: solid in a gas
Gas in liquid:
– Ex: whipped cream
Emulsion: liquid in liquid
– Ex: mayonnaise (oil suspended in water – use
egg yolk to
Sols: solid particles in a liquid
– Ex: Milk of Magnesia (solid magnesium
hydroxide in water)
Gels: Liquid in solid
– Ex: Quicksand: sand in water
Suspensions
(type of heterogeneous mix.)
• Particles are larger
• can be evenly distributed by
mechanical means (shaking the contents)
• Settle out on standing
• Homogeneous (aka solutions):
constant composition throughout,
individual components not visible
• Solutions in gas & liquid phases
transmit light
• particles not big enough to scatter light
• look translucent
RECAP:
Solution vs Suspension
• Solutions in gas & liquid phases
transmit light
• particles not big enough to scatter light
• look translucent
• Suspensions look cloudy
• particles big enough to scatter light
• settle on standing
Solution(homogenous) vs Suspension(heterogeneous)
CuSO4(aq)
Solution(homogenous) vs Suspension(heterogeneous)
Heterogeneous?
O
Or
O
Homogeneous?
H
H
F
-
O
H
F
H
O
H
-
O
H
O
-
H
H
F
H
F
-
H
F
H
-
O
F
O
F
-
H
H
H
-
F
O
-
H
H
Homogenous
Mixture:
Compounds &
elements
Both in liquid
phase
H
Compounds?
Or
Elements?
Solid?
Liquid?
Gas?
O O
O O
O O
K
K K
K K K
O O
Heterogeneous
Mixture:
elements &
elements
O2 in the gas
phase
K in the solid
phase