PPT on Physical changes in terms of arrangement and motion of atoms and molecules

1. CLASSIFICATION OF
MATTER

2. S8MT - IIIa - b - 8
•Explain the properties of solids,
liquids, and gases based on the
particle nature of matter;

3. Matter
Pure substance Mixture
Element Compound
Homogeneous Heterogeneous
Can it be separated by
physical process?
No Yes
Can it be
decomposed by
chemical
process?
Is it uniform
throughout?
No
No
Yes
Yes

4. INTRODUCTION
 Matter:  Anything that occupy space and has mass
 made up of very tiny units calls atoms
 Substance: a form of matter with a definite composition and
distinct properties
 Element:  a substance made up of one type of atoms
Compound: substance formed by the combination of 2 or
more different elements
 definite and constant composition

5. • Atom: smallest particle in substance
• Molecule:The smallest uncharged individual unit of compound formed
by the union of two or more atoms.
• Ion: An atom or molecule that has acquired a charge by either gaining
or losing electrons.
• Cation : positive charge
• Anion : negative charge

6. • Molecular compounds: are made of molecules
• each molecule has the same element composition and properties
as the compound
• Ionic compounds: are made of cations and anions
• cations combine with anions in just the right numbers to give an
electrically neutral compound
• Mixture: combination of two or more substances in which the
substances retain their distinct identities.

7. atom A
atom B
molecule A
molecule B
molecule AB
element
compound

8. element
compound
mixture mixture
element
mixture
Classify each of the following as an element, a compound or a
mixture:

9. Homogeneous mixture:
• the mixing is uniform.
• have a constant composition throughout.
• Homogeneous mixture are called solution
 gaseous solution (e.g: pure air)
 liquid solution (e.g: syrup)
 solid solution (e.g: steel, bronze) alloy

10. Heterogeneous mixture
 the mixing is not uniform.
 have regions of different composition.
 consist of two or more physically distinct phases
 eg: concrete (a mixture of cement, gravel, sand)

11. Classify each of the following as an element, a compound, a homogeneous
mixture or heterogeneous mixture:
a) Sulfur dioxide gas
 compound
b) Chlorine gas
 element
c) CuSO4 aqueous
 homogeneous mixture
d) Tomato juice
 heterogeneous mixture
e) Brass plate
 homogeneous mixture
Exercise

12. PROPERTIES OF MATTER
 Chemical properties: the ability of a substance to form new
substances, either by reaction with other substances or by
decomposition.
 E.g: rusting, combustion, decomposition
 Chemical change: the formation of a new substance with a
different composition and properties than the initial substance.

13. • Physical properties: a characteristic of a substance that can be
measured and observed without changing the composition or identity
of a substance.
 E.g: taste, odour, colour, temperature (melting/boiling points),
density.
 Physical change: a change in which the physical appearance of
a substance changes but the chemical composition stays the
same.

14. • Intensive properties: properties that do not depend on the amount of
the sample.
 E.g: temperature (melting/boiling points), density.
 Extensive properties: relate to the amount of substance
present.
 E.g: mass, volume.

15. Classify the following as physical or chemical properties of water
a) density = 1.00 g/mL
c) forms ice at 0°C
b) release hydrogen gas when
reacted with sodium metal
d)Water is formed when wood is burned
physical property: density can be
measured without changing a substance
to anything else
physical property: freezing is just
changing the physical state
chemical property: hydrogen
gas is a new compound formed
from water
chemical property

16. Does the following describe a physical change or a chemical
change?
a) Evaporation of water
 physical change (changes of state)
b) Hydrogen burns in air
 chemical change (H2 converted to H2O)
c) A piece of sliced apple turn brown
 chemical change

17. STATES OF MATTER
• Solid: molecules are held close together in an orderly structure with
little freedom of motion.
• Liquid: molecules are close together but are not held so rigidly in
position and can move past one another.
• Gas: molecules are separated by distances that are large
compared with the size of the molecules, thus they are much farther
apart and move freely of each other.
solid liquid gas

18. Water Molecule
Solid
0°C
Vapor
100°C
Liquid
0oC - 100°C

19. • Kinetic MolecularTheory: matter consist of particles called molecule in
constant movement colliding with each other.
• Heat given, matter will change states from solid to liquid to gas
• Each state will differ
• particle arrangement
• amount of kinetic energy
• difficulty to compress
• attractive forces between the particles
• movement of particles

20. GAS
LIQUID
SOLID
Condensation
Vaporization
Sublimation Deposition
Melting
(Fusion)
Freezing
Process of Changes in State of Matter

21. Temperature (oC)
time
-25°C
ice
water
water steam
vaporization
(liquid and vapor in equilibrium)
steam
Hfus
Hvap
(0°C)
melting point
100°C
boiling point
Ice water
Melting
(solid and liquid in equilibrium)
Heating Curve of Ice

22. Cooling Curve of Steam
Temperature (oC)
time
105°C
steam steam water
condensation
water
100°C
boiling point
(0°C)
melting point
ice
water ice
freezing
Super cooling

23. Super Cooling
• Cooling of a liquid below its freezing point without forming the
solid
• Occur when heat is removed from liquid so rapidly that the
molecules have no time to assume the ordered structure of a solid
• unstable

24. Phase Diagram of Water
0.01 oC
0.006
atm
Vapor
solid liquid
Triple point
critical point

25. • A diagram showing the conditions at which a substance exists
as a solid, liquid and vapor
• Each solid line between two phases specifies the conditions of
P andT under which the two phases can exist in equilibrium
• Triple point:
 the point at which all three phases can exist in equilibrium
 0.006 atm, 0.01 oC

26. • Critical Pressure
 the minimum P that must be applied to bring about
liquefaction at the criticalT. (Pc of water = 219.5 atm)
• CriticalTempt.
 the highestT at which a substance can exist as a liquid. (Tc
of water =374.4 oC)
 aboveTc, vapor phase cannot be made to liquefy, no
matter how great the applied pressure
Critical Point:

27. Question 1
Which is an example of a physical change?
A. *Steam from the boiling water condenses on the cooler
part of the ceiling.
B. The crude metal ore was first heated then combined
with pure oxygen gas to make the oxide of the metal.
C. A piece of paper burns in air with a smoky flame.
D. The table salt in the warehouse was used to make some
of the polymeric material.

28. Question 2
Which is an example of a chemical change?
A. Steam from the boiling water condenses on the ceiling.
B. The solid metal is heated until it melts.
C. The gas is cooled until it finally becomes a liquid.
D. *A piece of paper burns in air with a smoky flame.

29. Question 3
Which is an example of both a physical and a chemical change?
A. The milk in the carton became frozen because the carton was accidentally placed in
the freezing compartment overnight.
B. The bit of scrap metal was removed to the junkyard after being crushed by the heavy
machine.
C. The old parchment became dry when it was placed in the warm oven for ten minutes.
D. *Bubbles were seen on the egg shell soon after a sample of the vinegar was poured
on it.

30. Question 4
In the process of attempting to characterize a
substance, a chemist makes the following observation:
‘the substance is a silvery white metal. It melts at 649
oC and boils at 1105 oC. The substance burns in air,
producing an intense white light. It react with chlorine to
give a brittle white solid.’
Which of these characteristics are physical properties
and which are chemical properties?

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