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Chapter 4 States of Matter. Section 4-1 Solids. Quiz next class on Sec. 4-1. Everyday, water changes from a solid to a liquid to a gas and back again. How can we explain this?. Let’s do a quick review of what you already know:. Matter has three states: Solid Liquid Gas

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chapter 4 states of matter

Chapter 4States of Matter

Section 4-1

Solids

slide3

Everyday,

water changes from a

solid to a liquid to a

gas and

back again

How can we

explain this?

let s do a quick review of what you already know
Let’s do a quick review of what you already know:
  • Matter has three states:
      • Solid
      • Liquid
      • Gas

Matter is anything that takes up space and has mass.

more review
More review
  • Most matter is made up atoms and molecules.
  • An atom is the smallest particle that makes up a given element of matter.
  • When two or more atoms combine, they make a particle called a molecule.
examples of molecules

O

H

C

O

H

H

H

C

H

Liquid

Glucose

Blood sugar

O

Solid

O

C

H

H

O

C

H

Water

H

C

H

O

H

Gas

C

N

N

H

H

O

Nitrogen

H

Examples of molecules
slide7
???
  • Why is water a liquid, nitrogen a gas and glucose a solid?
  • What makes a solid a solid?

a liquid a liquid?

a gas a gas?

slide8
One clue to this mystery was first reported in 1827 by scientist Robert Brown –
    • Brownian Motion
slide10
The water molecules surrounding the dust particle are in constant, random motion.
  • When they hit the dust particle, they push it in random directions
matter in motion
Matter in motion
  • The idea that the particles (atoms and molecules) of all matter are in constant, random motion is called the kinetic theory of matter.
kinetic theory of matter
Kinetic Theory of Matter
  • All matter is made of atoms and molecules.
  • These particles are always in motion.
  • The higher the temperature, the faster the particles move.
  • At the same temperature, heavier particles move slower and lighter particles move faster.
temperature and heat
Temperature and Heat
  • What makes hot tea different from cold iced tea?
    • Same particles
    • movement of particles is different
  • Higher temp = faster moving particles
temperature and heat1
Temperature and Heat
  • Lower the temperature and the particles slow down.
  • At very low temperatures the motion of the molecules is very slow.
  • You cannot make things so cold that the motion completely stops,

but . . .

slide15
scientists have come close.

The temperature at which the particles of matter would completely stop is called

absolute zero.

slide16

Absolute zero is

- 273.15° C

You can’t get

colder than that,

no matter how

hard you try

transfer of heat
Transfer of heat
  • When hot matter touches colder matter, faster moving particles collide with slower moving particles.
  • The faster moving particles give some of their energy to the slower moving particles.
matter in the solid state
Matter in the solid state
  • In a solid, the particles vibrate or shake back and forth
  • but do not move from their position in respect to each other.
crystals or crystalline solids
Crystals or Crystalline Solids
  • Particles of crystals are arranged in repeating geometric patterns
slide22
Diamond, a form of carbon, is also a crystalline solid.
    • the crystals are shaped something like pyramids.
non crystalline solids
Non-crystalline solids
  • Many solids do not form crystals.
  • Their molecules do not arrange into repeating patterns
    • often because they are too large.
  • Examples:
    • glass
    • many plastics
how does a solid become a liquid
How does a solid become a liquid?
  • Start with very cold ice and gradually heat it.

If you could see the molecules, you would see each molecule shaking faster and faster,

  • but still held in one position by the other molecules around it.
keep heating your ice
Keep heating your ice
  • When the temperature reaches 0° C, the molecules begin to break free.
  • The molecules begin to move freely around each other.
  • The molecules enter the liquid state.
slide26
Melting point =

the temperature at which a substance changes from a solid to a liquid.

slide27

Temperature (C°)

60°

20°

-20°

0

Heat (kilojoules)

slide28

Temperature (C°)

60°

20°

-20°

0

Heat (kilojoules)

slide29
The amount of heat required to melt 1 kg of a solid is called its

heat of fusion

measured in

kilojoules per kilogram

kJ/kg

slide30

heat of fusion

Temperature (C°)

Heat (kilojoules)

slide31
Water’s heat of fusion is

334 kJ/kg

  • That is the same amount of energy you would spend if you climbed all the stairs in a 110-story tall building.

No, not a 110-foot tall building . . .

a 110-story building!

freezing
Freezing
  • As you know, if you can melt something, you can cool the liquid again to freeze it.
  • When you cool a liquid, the particles begin to slow down.
  • The attractive forces between the particles begin to catch the particles,

and crystals begin to form.

slide33
Freezing point =
    • the temperature at which attractive forces trap particles in a cooling liquid and form crystals.

Think: If the melting point of iron is 1,535° C, at what temperature does iron freeze?

non crystalline solids1
Non-crystalline solids
  • Non-crystalline solids, like glass, butter or wax, do not have a definite freezing or melting point.
  • If you slowly heat cold butter, it gradually gets softer and softer until it is completely liquid.
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