The States and Structure of Matter

Physical Science

The States of Matter

• States of matter are the physical forms in which a substance can exist:

Solid (crystalline and amorphous)

Liquids (with surface tension and viscosity)

Gas (pressure, Boyle’s Law and Charles's Law)

Plasma (conductivity)

States of Matter Intro

• http://www.youtube.com/watch?v=tBQcpF_j5Xg&feature=related

Solids

• When matter has a definite shape and volume. The particles are so close together that the atoms or molecules move, but not fast enough to overcome the gravitational attraction between them. Each particle is locked into place by the particles around it.

2 Types of Solids

• Crystalline solids – atoms/molecules are arranged in repeating pattern of rows. Ex: diamonds, ice and iron.

• Amorphous solids –atoms/molecules are not in a particular order or organized pattern. Ex: wax, rubber.

Liquids

• Liquids take the shape of the container they are in. The atoms can move fast enough to overcome the attraction between them. The volume remains the same, regardless of the container.

Liquid Properties

• Surface tension – the force that acts upon the particles at the surface of a liquid, causing the liquid to form spherical drops.

Viscosity – A liquid’s resistance to flow. The stronger the attraction between a liquid’s particles, the more viscous the liquid is. Example: Honey and motor oil (yum!)

Gases• Gas – the matter can change both shape and volume. The

atoms/molecules move so fast they can break away from the attraction from each other. As gases expand, there is actually empty space between particles.

• The more heat energy added to gas, the more the particles expand.

• Pressure – The amount of force exerted on a given area. The more gas you have in a given area, the more the crowded particles collide with each other at a faster rate.

Force • Pressure = Area

Characteristics of States of Matter

• http://www.youtube.com/watch?v=V9WYweBA6vA

Hydraulics

• when fluids (liquid or gas) in a container are pressed, the fluids move outward, causing pressure. This pressure can be a force that can do work. Example: dentist chair, car brakes.

Gas Laws(think pressure and volume)

• Boyle’s Law – For a fixed amount of gas at a constant temperature, the volume of this gas

increases as it’s pressure decreases.

Example: Balloons. If you squeeze a balloon, you are applying pressure to the gas inside. The particles of gas are forced to move close together. If you let go and release pressure, than the gas expands in volume.

How Boyle’s Law Works

Boyle’s Law and Weather Balloons

• When meteorologists release weather balloons, they only put a small volume of gas in each balloon. The balloon will travel to the upper layers of our atmosphere to get the information, where the air is thin.

• Partner share: How does this apply to Boyle’s Law? http://www.youtube.com/watch?v=QkHH68dvwjk&feature=fvst&safety_mode=true&persist_safety_mode=1

Demo of Boyle’s Law

• http://www.youtube.com/watch?v=Or0BWa7_wg4

Charles Law(think temperature and volume)

• For a fixed amount of gas at a constant pressure, the volume of the gas increases as its temperature increases. The volume of gas will decrease as the temperature decreases. Why?

When the temperature increases, the particles of gas move faster and expand as much as they can (increase volume). If it is cooler, the particles slow down and do not expand (decrease volume).

Charles’s Law

Demos of Charles’ Law and Boyle’s Law

• http://www.youtube.com/watch?v=al5f9q845q0

• http://www.youtube.com/watch?v=PqRmZYyIu3E

Last State of Matter: Plasma

• Plasma doesn’t have a definite shape or volume, and the particles have broken apart.

• However, plasma has conductivity, which means that an electric current can go through it. Electric and magnetic fields can affect plasmas, but not gases.

• Natural plasmas are found in lightning, fire and in the aurora borealis (Northern Lights).

• The artificial plasmas created in fluorescent lights are created by passing electrical currents through the

gasses.

Artificial and Natural Plasma

Changes of State

• All changes of state are physical changes.• The change requires a change in energy. If

energy is removed, then the particles move slower (water to ice). If energy is added, then the particles move faster (raising the temperature).

• Heat, which is a transfer of energy, causes temperature changes, which causes a change in state.

The 4 Changes of State

1)Melting Solids to Liquids – the melting point is the temperature when a solid becomes a liquid. Melting point is a characteristic property of a substance.

• Melting is an endothermic change, because energy is absorbed by the substance as it changes state. This energy increases the motion of the molecules until they can overcome their attractions to each other.

The 4 Changes of State(continued)

2) Freezing Liquids to Solids- This is at the substance’s freezing point.

Remember, you don’t loose energy (it changes form)

Proof that freezing and melting points are the same……

Ice Water: The energy added to 0oC will melt the ice, but it was removed at the same temperature to freeze the water! So why doesn’t the water freeze?

The 4 Changes of State(continued)

3) Vaporization: Liquids to Gases

- boiling is vaporization that occurs when a substance reaches its boiling point, which then leads to evaporation.

- Evaporation – vaporization that occurs at the surface of a liquid below it’s boiling point. The particles at the surface move fast enough to break away from the surrounding particles, and thus become a gas.

Boiling Point and Pressure (next question)

• Question:• You visit a friend in Denver, Colorado. You

are cooking pasta, and you notice that it takes very little time for the water to boil. It appears to boil much faster than it did in Atlanta. There must be some relationship between the higher altitude and the boiling point of water. What is it?

Boiling Point and Pressure

• There are layers of air on top and around every object on the surface of the Earth. The lower in altitude the object the more pressure on that object. Objects in higher altitude have less pressure on them, so they reach the boiling point faster than objects in lower altitudes.

The 4 Changes of State(continued)

4) Condensation – Gases to Liquids The condensation point of a substance is the

temperature at which the gas becomes a liquid and the same temperature as the boiling point at a given pressure.

Example: at sea level the same temperature that causes evaporation creates steam (condensation). The energy is removed (exothermic change) so that the molecules of the evaporated gas cool enough to slow down and clump together.

The “5th State” Sublimation

Sublimation - when solids go directly into a gas.

This can only occur when the atoms or molecules must move from being very tightly packed to being very spread apart (completely overcoming the attraction). This also requires energy (endothermic change).

Example: dry ice. Once heat energy is added, it goes from a solid to a gas.

Energy Exchange

• An endothermic change occurs when an object is receiving thermal energy. Examples: Ice cube melting, the air around your breath on a cold day..

• An exothermic change occurs when an object loses thermal energy (heat). Examples: your hand holding the ice, your breath on a cold day.