Physics Review

Physics Review

By Olivia Rodríguez

8°C #10

General Info

Internal Motion of Matter

A molecule is the smallest part of a substance with all the properties of the substance.

If a small amount of gas has a distinctive odor and is released in one corner of the room, it'll be gradually detected in the whole room. This self-spreading gas is known as diffusion.

General Info

Space Between Molecules

The spaces among molecules are the greatest in gases, less in liquids, and least in solids. Substances generally contract into smaller volumes when they are cooled. The such contraption is explained by assuming that during cooling the molecules of a substance are pulled closer, thus reducing the empty spaces between them.

General Info

Attraction Between Molecules

At close distances, molecules attract each other. We can distinguish two kinds of attraction, adhesion, and cohesion.

Adhesion is the force by which unlike molecules attract each other.

Cohesion is the force by which like molecules attract each other. Is greater in solids, weaker in liquids, and in gases the forces are negligible.

General Info

Structures in solids

In solids, the attractive forces of the molecules are strong enough to hold the body together and able to keep it in a definite and unchanging shape.

In liquids, the molecules vibrate more vigorously than they do in solids.

In gases, the molecules are at least ten times apart that in liquid or solid shape, with practically zero attractive forces.

General Info

Heat and Internal Energy

Heating in a body increases both the kinetic and potential energy of all the molecules of a body is known as internal energy or thermal energy.

• Heat absorbed by a body is stored in it as internal energy in the form of the kinetic and potential energy of its molecules.

General Info

Molecular Explanation of Changes of States

In a molecular POV, the heat applied to the solid first increases both the kinetic and potential energies of its molecules. The rise in kinetic energy is the temperature rise. The increased potential energy results from the melting point of the solid being reached other to let them move freely through the liquid that is forming.

General Info

Molecular Explanation of Changes of States

None of it goes to increase the kinetic energy of the molecules. Thus, the temperature remains the same until all the solid has turned into liquid.

As the liquid is now heated, the process is now repeated.

General Info

Molecular Explanation of Changes of States

None of it goes to increase the kinetic energy of the molecules. Thus, the temperature remains the same until all the solid has turned into liquid.

As the liquid is now heated, the process is now repeated.

General Info

Chemical Elements

1661, English scientist Robert Boyle suggested that in nature there were only a limited number of different simple substances called elements.

The major property is that it cannot be subdivided by chemical means into parts or substances different from itself. Boyle asserted that all other substances are simply combinations of two or more elements.

General Info

Chemical Elements

Boyle proposed the idea that all matter consists of combinations of a limited number of elements.

General Info

Law of Definite Proportions

The law of definite proportions states that whenever two or more elements form a particular compound, the elements combine in definite proportions by weight. These proportions are always the same for any sample of that compound.

General Info

Law of Definite Proportions

John Dalton (1766-1844) suspected the existence of basic particles of matter called atoms and proposed a theory describing their behavior.

General Info

Theory of Atoms

Dalton suggested that each of the chemical elements is composed of tiny, indestructible particles or atoms, which, for any given element, are exactly alike.

Compounds are made when the atoms of two or more elements combine.

General Info

Theory of Atoms

The smallest unit of a compound is a molecule.

When different atoms unite to form any given molecule, the atoms always combine in the same definite proportions.

Ready for the quiz?

Open Ended

How do you know if a solid has empty spaces between molecules?

Multiple Choice

The force with which unlike molecules attract each other

• Difussion

• Adhesion

• Cohesion

• Atoms

Multiple Choice

The force with which like molecules attract each other

• Difussion

• Adhesion

• Cohesion

• Atoms

Multiple Choice

In cohesion, when is it at its most attractive?

• Liquids

• Aerosols

• Solids

• Gases

Multiple Choice

(The answer wasn't in the presentation) What is the boiling point of water?

• I don't know

• 100ºC

• 140ºF

• 200ºC

Multiple Choice

(Not in presentation) If you can see it, it's not a gas. What is it then?

• Vapor

• Aerosol

• Water

• I don't know

Technically it isn't water, sorry if you answered that.

Multiple Choice

(From now on, it isn't in the presentation) What is the Third Law of Thermodynamics?

• There is no process by which a body may be cooled to a temperature of 0K (Kelvin), that is, absolute zero.

• Heat flows spontaneosly only from a body at a higher temperature to one at a lower temperature. To reverse the flow, work must be done.

• Whenever heat is transformed into work or another form of energy is transformed into heat, there is no loss of energy.

• If two systems are in thermal equilibrium with a third system then those two are in thermal equilibrium with each other.

Thermodynamic Laws

Third Law:

There is no process by which a body may be cooled to a temperature of 0K (Kelvin), that is, absolute zero.

Thermodynamic Laws

Second Law:

Heat flows spontaneously only from a body at a higher temperature to one at a lower temperature. To reverse the flow, work must be done.

Thermodynamic Laws

First Law:

Whenever heat is transformed into work or another form of energy is transformed into heat, there is no loss of energy.

Thermodynamic Laws

Zeroth Law:

If two systems are in thermal equilibrium with a third system then those two are in thermal equilibrium with each other.

Multiple Choice

Definition of Entropy

• Quantative way of expressing the irreversibility that heat cannot flow in the opposite direction.

• The sum of potential and kinetic energies of the individual molecules of which its made.

• Relationship between work and heat.