Classifying Matter
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Transcript Classifying Matter
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