3.1 Solids, Liquids, and Gases 3-1 C. notes Describing the States of Matter –Solids –Liquids...

3.1 Solids, Liquids, and Gases

3-1 C. notes

• Describing the States of Matter

– Solids

– Liquids

– Gasses

– Other States of Matter

• Kinetic Theory

• Explaining the Behavior of Gas

– Motion in Gases

– Kinetic Theory of Gasses

• Explaining the Behavior of Liquids

• Explaining the Behavior of Solids


I. Solids, Liquids, and Gases.

A. Materials can be classified as solids, liquids, or gases based on whether their shapes and volumes are definite or variable.

1. Solid - the state of matter in which materials have a definite shape and a definite volume.

a. Almost all solids have some type of orderly arrangement of particles at the atomic level.


Samples of solid copper have definite volume. Copper atoms are packed close together in an orderly arrangement.


2. Liquid the state of matter in which a material has a definite volume but not a definite shape.


LiquidsAt room temperature, mercury is a liquid. Drops of mercury on a flat, clean surface have a round shape. Mercury in a container has the same shape as its container. The mercury atoms are close together, but their arrangement is more random than the arrangement of atoms in solid copper.

Describing the States of Matter


3. Gas-the state of matter in which a material has neither a definite shape nor a definite volume.

a. A gas takes the shape and volume of its container.


GasesThese balloons are filled with helium, a colorless gas that is less dense than air. Two of the balloons are teardrop-shaped, and two are disk-shaped. The “shape” of the helium in a balloon is the same as the shape of the balloon itself. The volume of the helium in a balloon is equal to the volume of the balloon.



GasesThe helium atoms in a balloon are not arranged in a regular pattern. They are at random locations throughout the balloon.

Because of the space among helium atoms, a large amount of helium can be compressed into a metal cylinder. When helium flows from the cylinder into a balloon, the helium atoms spread out. The helium can fill balloons with much more volume than the cylinder.



4. Plasma- a state of matter in which atoms have been stripped of their electrons and the electrons move outside of their shell.

a. At extremely high temperatures, such as those found in stars, matter exists as plasma.

b. Plasma is found here on earth in the form of lightning.

c. The most common state of matter in the universe.

5. Bose-Einstein condensate (BEC)- at extremely cold conditions, atoms behave as though they are a single particle.


B. Kinetic Theory

1. The kinetic theory of matter says that all particles of matter are in constant motion.

A ball thrown at 137 kilometers per hour has more kinetic energy than a ball thrown at 125 kilometers per hour.

According to the kinetic theory of matter, particles inside the solid baseball are also moving. The kinetic theory was developed to explain the behavior of gases. It can also help to explain the behavior of liquids and solids.


The motion of billiard balls can be compared to the motion of particles in a gas.

• The cue strikes a ball and the ball moves in a straight line until it strikes the side of the table or another ball.

• When a moving ball strikes a ball at rest, the first ball slows down and the second ball begins to move.

• Kinetic energy is transferred during those collisions.

Explaining the Behavior of Gases


This photograph was taken just after the cue struck the white ball, which began to move. The white ball moved in a straight line until it collided with the dark blue ball.



1. Motion in Gases

a. At room temperature, the average speed of the particles in a sample of gas is about 1600 kilometers per hour.

b. Some particles are moving faster than the average speed, and some are moving slower than the average speed.

c. There are forces of attraction among the particles in all matter.

C. Explaining the Behavior of Gases


This illustration shows the possible paths of two helium atoms in a container of helium gas.

• Each atom moves in a straight line until it collides with the other atom or the container.

• During a collision, one atom may lose kinetic energy while the other atom gains kinetic energy.

• The total kinetic energy of the atoms remains the same.



a. Particles in a gas are in constant, random motion.

b. The constant motion allows a gas to fill a container of any shape or size.

c. The motion of one particle is unaffected by the motion of other particles unless the particles collide.

d. Forces of attraction among particles in a gas can be ignored under ordinary conditions.

2. Kinetic theory of gases explains the general properties of a gas


A mercury atom in liquid mercury can be compared to a student in a crowded hallway. The student’s path may be blocked by students moving in the other direction. The student’s ability to move is affected by interactions with other students.

Explaining the Behavior of Liquids


In a liquid, there is a kind of tug of war between the constant motion of particles and the attractions among particles. This tug of war explains the general behavior of liquids.

Because forces of attraction limit the motion of particles in a liquid, the particles in a liquid cannot spread out and fill a container.

Explaining the Behavior of Liquids


1. The particles in a liquid are more closely packed than the particles in a gas. Therefore, attractions between the particles in a liquid do affect the movement of the particles.

2. A liquid takes the shape of its container because particles in a liquid can flow to new locations.

3. The volume of a liquid is constant because forces of attraction keep the particles close together.

D. Explaining the Behavior of Liquids


You might compare the particles in a solid to a polite audience in a movie theater. Although people move around in their seats, each person remains in essentially the same location during the movie. They have “fixed” locations in a total volume that does not change.

Explaining the Behavior of Solids


1. Solids have a definite volume and shape because particles in a solid vibrate around fixed locations.

2. Vibration is a repetitive back-and-forth motion.

Think about the atoms in solid copper.•Strong attractions among the copper atoms restrict their motion and keep each atom in a fixed location relative to its neighbors. •Each atom vibrates around its location, but it does not exchange places with a neighboring atom.

E. Explaining the Behavior of Solids


Assessment Questions

1. Materials are classified as solids, liquids, or gases based on their a. temperature and density.

b. chemical composition.

c. shape and volume.

d. reactivity.



1. Materials are classified as solids, liquids, or gases based on their a. temperature and density.

b. chemical composition.

c. shape and volume.

d. reactivity.

ANS: C



2. Which of the following statements describes gases based on the kinetic theory?a. Particles of gas are in motion part of the time and

stationary part of the time.

b. Particles in a gas are arranged in an orderly fashion.

c. Gas particles are not affected by collisions with other gas particles.

d. Forces of attraction between particles can be ignored under ordinary conditions.



2. Which of the following statements describes gases based on the kinetic theory?a. Particles of gas are in motion part of the time and

stationary part of the time.

b. Particles in a gas are arranged in an orderly fashion.

c. Gas particles are not affected by collisions with other gas particles.

d. Forces of attraction between particles can be ignored under ordinary conditions.

ANS: D



3. Most of the matter of the universe exists in which state? a. solid

b. gas

c. plasma

d. Bose–Einstein condensate



3. Most of the matter of the universe exists in which state? a. solid

b. gas

c. plasma

d. Bose–Einstein condensate

ANS: C

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3.1 Solids, Liquids, and Gases 3-1 C. notes Describing the States of Matter –Solids –Liquids...

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