Phases of MatterPhases of Matter

Contents :Contents :

DensityDensity

Solids, liquids, and gasesSolids, liquids, and gases

Pressure in the fluidsPressure in the fluids

Change of phaseChange of phase

DensityDensity

The density of a substance is defined The density of a substance is defined as it’s mass per unit volume.as it’s mass per unit volume.

Density = mass/volumeDensity = mass/volume

ρ= m/V, unit is Kgmρ= m/V, unit is Kgm-3-3

questionquestion

Which substance in the world has the Which substance in the world has the highest density?highest density?

nucleus= 10nucleus= 1018 18 KgmKgm-3-3

SolidsSolids

has regular, geometrical has regular, geometrical structure in which the atoms structure in which the atoms or molecules are closely or molecules are closely packed in a regular pattern packed in a regular pattern called a space-lattice. This called a space-lattice. This accounts for the fact that accounts for the fact that solids have a high density.solids have a high density.

Has a fixed volume and a Has a fixed volume and a fixed shape. To a certain fixed shape. To a certain extent, solids return to their extent, solids return to their original shape when stretched original shape when stretched or compressed.or compressed.

A typical inter-atomic distance A typical inter-atomic distance in a crystal is about 3 x 10in a crystal is about 3 x 10--

1010m.m.

LiquidsLiquids

The molecules are slightly The molecules are slightly further apart than in a further apart than in a solid, resulting also in high solid, resulting also in high density. They occur in density. They occur in clusters and the molecules clusters and the molecules can move between them.can move between them.

Fixed in volume but not in Fixed in volume but not in shape. Liquids take the shape. Liquids take the shape of the container and shape of the container and are almost incompressible.are almost incompressible.

The order of separation of The order of separation of molecules in liquids is molecules in liquids is about the same as that for about the same as that for solids.solids.

GasesGases

The molecules are very far apart The molecules are very far apart in a gas, thus giving rise to a low in a gas, thus giving rise to a low density.density.

No fixed volume or shape. Gases No fixed volume or shape. Gases fill up the entire space/ container fill up the entire space/ container in which they are placed. They are in which they are placed. They are easily compressible.easily compressible.

At s.t.p. (standard temperature At s.t.p. (standard temperature and pressure). The average and pressure). The average separation of gas molecules is separation of gas molecules is about 33 x 10about 33 x 10-10-10m.m.

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Brownian motion Experiment Brownian motion Experiment conclusionconclusion

The motion of the smoke particles is evidence The motion of the smoke particles is evidence that air molecules are also moving, which that air molecules are also moving, which explains why the tiny smoke particles are explains why the tiny smoke particles are being knocked about by “invisible” particles.being knocked about by “invisible” particles.

Brownian MotionBrownian Motion This random motion of smoke particles, which This random motion of smoke particles, which

demonstrates that air molecules move demonstrates that air molecules move randomly in all directions with a range of randomly in all directions with a range of speeds.speeds.

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Crystalline solidsCrystalline solids

Most solids, including metals and Most solids, including metals and many minerals, are crystalline in many minerals, are crystalline in structure.structure.

X-ray diffraction patterns show that X-ray diffraction patterns show that metals are crystalline. metals are crystalline.

A crystal is defined as a copection of A crystal is defined as a copection of atoms or molecules in which each atoms or molecules in which each atom is placed precisely in a definite atom is placed precisely in a definite pattern with respect to its neighbors pattern with respect to its neighbors

FCC

BCC

HCP

Non-Crystalline SolidsNon-Crystalline Solids

AmorphousAmorphous or non-crystalline solids have or non-crystalline solids have their particles assembled in a more their particles assembled in a more disordered way and only show order for disordered way and only show order for short distance.short distance.

PolymersPolymers are substances which have are substances which have giant molecules, each containing giant molecules, each containing something like 1000 to 100 000 atoms, and something like 1000 to 100 000 atoms, and are usually carbon (organic) compounds.are usually carbon (organic) compounds.

Pressure in the fluidsPressure in the fluids

PressurePressure is defined as the force is defined as the force acting normally, per unit area.acting normally, per unit area.

The SI unit of pressure is 1 Newton The SI unit of pressure is 1 Newton per meterper meter22, (N/m, (N/m22). This unit is also ). This unit is also called the Pascal (Pa).called the Pascal (Pa).

Derivations of pressure Derivations of pressure formula for gas:formula for gas:

ρ= F/Aρ= F/A = mg/A = mg/A = ρvg/A = ρvg/A = ρhAg/A = ρhAg/A = hρg = hρg

mg is the weight of the liquid*mg is the weight of the liquid*

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Change of PhaseChange of Phase

MeltingMelting : when ice melts to form water, the change of state is : when ice melts to form water, the change of state is called fusion. The heat energy which changes ice to water is called called fusion. The heat energy which changes ice to water is called the latent heat of fusion.the latent heat of fusion.

BoilingBoiling : a process where liquid changes to gas at boiling : a process where liquid changes to gas at boiling temperature. (impurities raise the boiling point)temperature. (impurities raise the boiling point)

EvaporationEvaporation : the change of state of a liquid into its vapour, at : the change of state of a liquid into its vapour, at any temperature.any temperature.

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