Physical ScienceSolids, Liquids, and Gases

There are 4 different states of matter:

• A. Solid

• B. Liquid

• C. Gas

• D. Plasma

Kinetic Theory of Matter• All matter is made of tiny particles (atoms or

molecules) which are in constant motion.

• How tightly these particles are packed together and how strongly they are bonded will determine what state of matter the material is.

• Think of it like a snowball. The more tightly you pack it, the more strongly the flakes (particles) are bonded together. Pack it loosely, and the flakes are more likely to fly apart (loosely bonded).

• Also, particles vibrate more or move around more quickly if the matter is heated up. Conversely they also slow down as they are cooled.

• Adding and removing heat is the #1 way to change a material from 1 state of matter to another. (we’ll talk about this later)

• What is the relationship between the temperature of the particles and their rate of movement or vibration?

Solids

• Have a definite shape and a definite volume

• Particles are tightly packed and are bonded together relatively strongly

• Diamonds form under tremendous pressure, and therefore their particles (carbon atoms) are packed very tightly. This is one reason why diamonds are so hard.

Liquids• Have a definite volume, but no definite shape

(they take the shape of their container)

• Particles move around freely within the liquid.

Viscosity in fluids• Viscosity is the property of a fluid which

describes how well it will flow

• Low viscosity flows easily, high viscosity is much thicker.

Gases

• Gases have no definite volume and no definite shape (but do have mass). They simply take the shape of the container they are in.

• Gas particles are very loosely bonded and move around freely.

• Gases, unlike solids and liquids, are fairly easy to compress and also readily expand. That is why we say they have no definite volume.

• Expansion and contraction of gases explains why warm air rises and cold air sinks.

• Why does it hurt more to jump onto a water bed than on an air mattress?

• Plasma, the 4th state of matter, is the most common state of matter in the universe. It is a gas-like mixture of positive and negatively charged particles.

These particles make plasma a high energy state of matter.

• A plasma TV has a large number of tiny cells containing xenon and neon gases. When an electric current is passed through these individual cells, they give off energy which causes phosphors inside the cell to give off light. These tiny lights combine together to produce an image.

Changes of state

• By adding or removing thermal energy from a sample of matter, it is often possible to cause it to change from one state of matter to another.

Melting and Freezing

• Adding thermal energy can change some materials from a solid to a liquid (melting)

• Removing thermal energy may change some materials from a liquid to a solid (freezing)

• Let's say an ice storm knocks out your power so you light some candles.

As the melted wax drips off, it solidifies as it cools. Is this considered freezing?

Condensation & Evaporation

• Changing a gas to a liquid is called condensation (loses heat)

• Ex.: breathing on a cold window, warm air rising and forming clouds, droplets on a cold glass, dew

• Evaporation is where a liquid changes to a gas (gains heat).

• Ex.: steam rising from a hot liquid, sweat cooling your body, a steam locomotive

• Is boiling the same as evaporation?

• How do the bubbles magically appear in a pot of boiling water?

Sublimation• Changing a solid directly to a gas is called

sublimation.

• Examples: dry ice, frost on a window