Topic: Classifying Matter Which of the following is a physical change that requires energy? a)H 2 O...
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Transcript of Topic: Classifying Matter Which of the following is a physical change that requires energy? a)H 2 O...
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
Substances Mixtures
Elements Compounds HeterogeneousMixtures
HomogeneousMixtures
Mixtures Separated by physical methodsCompounds Separated by chemical methods
Can it be separated by physical methods
NO YES
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
F F FF
Cu
Cu
Cu
F2
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
FF
FF
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
H
H HO
H
HCl
Cl
Cl
H HO
HCl
H2O
2Na + Cl2 2NaCl
Atoms or Molecules?
Element or Compound?
Na = atom, element
Cl2 = molecule, element
NaCl = molecule, compound
Particle Diagrams
Molecules of a triatomic (3) compound
Mixture: monatomic element, diatomic element, triatomic compound
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)
GraniteOil in water 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
K
O
H
KKK
K
O
O O
K
HO
H HO
H HO
H HO
H HO
H HO
H HO
H HO
HO
F- F
-
F-
F-
F-
F-
F-
F-
O O
O O
Homogenous Mixture:Compounds & elementsBoth in liquid phase
Heterogeneous Mixture:elements & elementsO2 in the gas phaseK in the solid phase
Heterogeneous?
Or
Homogeneous?
Compounds?
Or
Elements?
Solid?Liquid?
Gas?