Properties of MatterChapter 6

6.1 MatterObjectives•Define matter and describe its major properties.•Explain how the arrangement of particles in a substance may determine its properties.•Classify kinds of matter based on their properties.•Make a model illustrating the particle model of matter

Matter

• Imagine you are an astronaut approaching the earth from space.

• If you land on a beach, you see sand and waves.

• Looking closer, you see even the individual grains of sand that make up the beach.

• Do you think the grains of sand are made of things that are still smaller?

Particle Model of Matter•Grains of sand and everything else you see, hear, smell, touch, and taste are made of matter.•Matter is anything that has mass and takes up space.•Matter exists in many shapes, colors, textures, and forms. Water, rocks, living things, and•stars are all made of matter.

Matter

• All forms of matter are made up of tiny particles that are in constant motion.

• This idea is known as the particle model of matter.

• Matter contains huge numbers of particles that vary in their size, shape, arrangement, motion, and individual properties.

Properties of Matter

•Matter has characteristics that help to identify it.•These characteristics are known as properties.•Some properties such as mass, volume, and density are common to all matter.

Properties of Matter

• You can observe many other properties of matter using your senses.

• Some properties that are easily observed include color, texture, odor, luster, and transparency.

Properties of Matter

Properties of Matter

• Many other properties of matter can be observed by using simple tests and measurements.

• Some of these properties include resistance to breakage, and the ability to dissolve in water, how they interact with other substances, and how they are affected by temperature changes.

Properties of Matter

Explaining Matter's Properties

Explaining Matter's Properties•Many other properties of matter are determined by the characteristics of the particles themselves.•For example, particles that reflect green light give a substance the property of being green in color.•The particles in baking soda, not their arrangement, account for how it reacts in vinegar.

Explaining Matter's Properties•The motion of the particles in matter is also important.•Particle movement determines whether a substance will be a solid, liquid or gas.

Check & Explain pg. 139Answer Questions 1 & 2

6.2 Phases of MatterObjectives•Give examples of solids, liquids, and gases.•Relate the particle model to solids, liquids, and gases.•Make models illustrating the gas laws.

Familiar Phases of Matter

• The three most familiar states of matter are solid, liquid, and gas.

• Each of these states of matter is called a phase.

• Particles of matter in each phase are arranged differently and have different ranges of motion.

SOLIDS•When matter has a definite shape and a definite volume, it is a solid.•A solid has these characteristics because of its closely packed particles.•The particles can move slightly, but they do not change positions.

SOLIDS

•Most solids occur as crystals.

•Salt, bones, diamonds, computer chips, and snowflakes are all made up of crystals.

•Particles in a crystal are arranged in a regular, orderly way.

Liquids•Matter with a definite volume, but no definite shape, is a liquid.•Particles in a liquid easily slide over each other. As a result, a liquid will take the shape of its container.

Gases

•Matter that has no definite shape and no definite volume is a gas.•Like a liquid, a gas will take the shape of any container.•Unlike a liquid, a gas expands to fill whatever space is available.

Gases•Unlike the particles in a solid or liquid, each gas particle is mostly unaffected by its neighbors.•Only temperature and pressure can affect the way the particles move and the volume they occupy.•Because each gas particle is independent of other gas particles, the behavior of gases can be described by general laws.

Gases - Boyle's Law

• A gas sealed in a container exerts a certain pressure.

• Pressure is the force created by particles striking the walls of a container.

• You have seen the effect of pressure on the rubber walls of balloons many times.

• The walls of the balloons are pushed out by the constant bumping of the gas particles trapped inside.

Gases - Boyle's Law•If you squeeze the balloon, the air inside will be pushed into a smaller space.•The air particles will strike the walls of the container more often.•The pressure on the walls will increase.•If you increase the space, the gas particles strike the container's walls less often and the pressure will decrease.

Gases - Boyle's Law•This relationship between pressure and volume is called Boyle's Law.•It was discovered by Robert Boyle, a British scientist who lived in the 1600s.•Boyle's Law states that if a sample of gas is kept at a constant temperature, decreasing its volume will increase the pressure the gas exerts.

Gases - Boyle's Law•Boyle's Law can be tested using a cylinder with a movable piston like the one here.

Gases - Boyle's Law

Animated Boyle's Law

Glenn

Research

Center

Gases – Charles Law

•According to Charles' Law, if a sample of gas is kept at constant pressure, its volume increases as the temperature increases.•Many products in spray cans, such as whipped cream and paint, contain gas at a fairly high pressure.•Their labels warn you to keep them away from heat or fire. Why?

Answer - Charles Law

•Adding heat energy to a gas causes the gas particles to move faster.•When the particles move faster, they strike the walls of their container harder and more often. If the container walls aren't flexible, as in a can of spray paint, the pressure of the gas will increase.•Since the can will withstand only so much pressure, the result could be explosive and dangerous!

Gases – Charles Law

•However, if a gas in a container with flexible walls is heated, the volume of the gas will increase.

•What happens when the same balloon is cooled?

Gases – Charles Law

Plasmas•At very high temperatures, over 1 1,000,000 0C, gas particles break down, forming a plasma.•Plasma, called the fourth phase of matter, is the most common phase of matter in the universe. •The sun and other active stars are made up mostly of plasmas. These plasmas are formed from the gases hydrogen and helium.

Plasmas•Plasmas have unusual properties that gases do not have.

•Temperatures high enough to form plasmas exist naturally only in stars.

•On earth, plasmas can be manufactured and studied only in special laboratories able to handle the extreme temperatures at which plasmas exist.

Check & Explain pg. 146Answer Questions 1 & 2

6.3 Changes in Matter

OBJECTIVES:•Give examples of physical and chemical changes.

•Compare and contrast physical and chemical changes.

•Interpret data about a phase change.

Physical Changes in Matter

• When matter undergoes a change in size, shape, or phase, it is a physical change.

• Breaking glass, cutting wood, grinding coffee are all physical changes.

• Is freezing water a physical change?• Physical changes do not change the

particles that make up matter. The arrangement of the particles, however, may be moved around during a physical change.

Physical Changes in Matter

• Are you causing a physical change when you mix sugar and water?

• A mixture of salt or sugar and water can be compared to a mixture of water and pebbles.

• The pebbles can be separated with a strainer.

• Salt or sugar particles are too small for you to separate by hand or strainer. However, the water can be boiled away, leaving the salt or sugar behind.

Physical Changes in Matter• Physical changes help shape the

earth's surface.

Chemical Changes in Matter• In a chemical change, particles of one

substance are changed in some way to form particles of a new substance that has new and different properties.

• The production of heat or light, the appearance of gas bubbles, and the formation of a solid all indicate that a chemical change has taken place.

Physical vs. Chemical Changes

• The earth’s surface is shaped by chemical changes as well as physical changes.

• Gases in the atmosphere and water combine with minerals in rocks to create new substances. These chemical changes weaken rocks so that they chip, crack, and break apart more easily.

• Chemical weathering happens to rocks all over the earth's surface.

• Chemical changes work together with physical changes to weather and erode the earth's surface.

Physical vs. Chemical Changes

• A chemical change makes a substance that wasn't there before.

• There may be clues that a chemical reaction took place, such as light, heat, color change, gas production, odor, or sound.

Physical vs. Chemical Changes

• The starting and ending materials of a physical change are the same, even though they may look different.

• Any change in phase, for example, can be reversed. Ice can melt to form water and water can freeze to form ice.

• Usually only physical changes can be reversed.

Physical or Chemical Change ?

• When you freeze water ( )• Casting silver in a mold ( )• When you burn wood in your fireplace ( )• When iron (Fe) rusts ( )• Melting a sugar cube ( )• When you step on a can and crush it ( )• When you cook an egg ( )• Solid iodine evaporating into a purple gas ( )• Taking an antacid to neutralize stomach acid ( )

P

P

P

C

P

P

C

C

C

Check & Explain pg. 151Answer Question 3