Three States of Matter

Chapter 3 Section 1

Particles of Matter

• The states of matter are the physical forms in which a substance can exist.

• The three most familiar states are solid, liquid, and gas. (Plasma is the 4th state.)

• Matter is made of tiny particles called atoms and molecules which are always in motion.

• The way these particles interact helps determine the state of the matter.

Figure 1, Page 66

• Figure 1 on page 66 describes the three familiar states of matter in terms of the speed and attraction of the particles.

• Solids – molecules are highly attracted to each other and vibrate

• Liquids – molecules are close and slide past each other

• Gas – little attraction because a lot of motion

Solids

• Solid – the state in which the substance has a definite shape and volume

• The attraction between particles is stronger than the particles of the same substance in the liquid or gaseous state.

• Particles in a solid move, but only vibrate in their place.

Types of Solids

• Crystalline solid – have a very orderly, 3-D arrangement of particles; particles repeat in a pattern

• Examples of crystalline solids are iron, diamond, and ice.

• Amorphous solid – particles do not have a particular arrangement; substance can change shape under certain conditions

• Examples of amorphous solids are glass, rubber, and wax.

Liquids

• Liquid – the state in which the substance has a definite volume but no definite shape

• Particles move fast enough to overcome some of the attraction between them.

• Molecules slide past each other to take the shape of the container.

• The shape of a liquid can change, but the volume cannot.

Characteristics of Liquids

• Surface Tension – a force that acts on the particles at the surface of a liquid

• Surface tension causes some liquids to form spherical drops and is different in different types of liquids.

• Viscosity – a liquid’s resistance to flow• The stronger the attraction between the molecules

of a liquid, the more viscous the liquid is.

Gases

• Gas – the state of matter that has no definite shape or volume.

• Particles of a gas move quickly so there is less attraction between the particles.

• The amount of empty space between gas particles can change depending on the container the gas is in.

Behavior of Gases

Chapter 3 Section 2

Temperature

• Temperature is a measure of how fast the particles in an object are moving.

• The faster the particles are moving the more energy they have.

• On a hot day, gas particles move faster than on a cold day. Therefore, there is more pressure on the walls of the container holding the gas when the temperature is high.

Temperature

• Less gas is needed to fill a balloon in warm temperatures because the particles of the gas have more energy.

• At cool temperatures particles move slower.

• To fill a balloon in cool temperatures more gas is needed because the particles of the gas have less energy.

Temperature

• As external temperatures increase, the gases in a balloon expand and the balloon could pop.

• When external temperatures decrease, the gases in a balloon condense and the balloon shrinks.

Volume

• Volume is the amount of space an object takes up.

• Particles of gas spread out, so the volume of a gas depends on the container the gas is in.

• Intro to PVT gases

Pressure

• The amount of force exerted on a given area of surface is pressure.

• The basketball and beach ball in Figure 2 on page 71 hold the same volume of air.

• There are more particles inside the basketball colliding with the inside surface of the ball.

• There is more pressure in the basketball.

Gas Behavior Laws

• The temperature, pressure, and volume of a gas are linked.

• Changing one of these factors will change the other two.

• Gas laws describe the relationships between temperature, pressure, and volume.

Boyle’s Law

• Boyle’s Law states that for a fixed amount of gas at a constant temperature, the volume of the gas is inversely related to pressure.

• As the pressure of a gas increases, the volume decreases by the same amount.

Charles’s Law

• Charles’s Law states that for a fixed amount of gas at a constant pressure, the volume of the gas changes in the same ways that the temperature of the gas changes.

• Decreasing the temperature of the gas causes the volume of the gas to decrease.

• Increasing the temperature of the gas causes the volume of the gas to increase.