Chapter 20 “Materials ”

Aim: to understand the particle nature of matter You will know by the end of this section: Matter, states of matter. Exp gases have mass and take up space. Properties of states of matter Solids (3) Liquids (3) Gases (3) Particle theory of matter Solids (3) liquids (3) gases(3) Diffusion, explain with particle theory Compression explain with particle theory Change of state = ? Melting point, evaporation, boiling point, condensation (+ 2 examples)

Matter Matter is anything that: a) has mass, and b) takes up space Mass = a measure of the amount of “stuff” (or material) the object contains (don’t confuse this with weight, a measure of gravity) Volume = a measure of the space occupied by the object

Showing that gas takes up space Place a dry tissue in the bottom of a glass. Press the glass upside down into a basin of water. What happens? Air is trapped in the glass. The tissue does not get wet. Air takes up space.

Showing that gases have mass one baloon is filled with air whilst the other balloon is not, both balloons are the same size. What happens? When the balloons are set up as shown in the picture the balloon filled with air pulls down the meter stick. Air has mass, gases have mass.

What are some Physical Properties? Properties you can see, such as color, shape, hardness, and texture Properties that are easily measured, such as mass, volume, density, melting point, boiling point Note! Freezing and melting point are the same temperature! Density = Mass ÷ Volume Is the ability to be attracted to a magnet a physical property?

Properties of Matter AIM Know three states of matter. Explain the states of matter using the particle theory.

Properties are… Are the characteristics of matter Physical Properties- Examples- color, hardness, m.p., b.p. Chemical Properties- chemical reactions of that substance. Examples- ability to burn, decompose, ferment, react with, etc.

States of matter Solid- matter that can not flow (definite shape) and has definite volume. Liquid- definite volume but takes the shape of its container (flows). Gas- a substance without definite volume or shape and can flow.

States of Matter Definite Volume? Definite Shape? Solid Liquid Gas Result of a TemperatureI ncrease? Definite Volume? Definite Shape? Will it Compress? Small Expans. Solid YES YES NO Small Expans. Liquid NO NO YES Large Expans. Gas NO NO YES

States of matter explained with particles. Remember to show SEP particles in motion animation

The Particle Theory of Mater Matter is imagined to be made up of small particles (atoms or molecules) It is how these particles are arranged and the amount of energy they have to move that is used to explain how solids liquids and gases behave.

Three Main states of matter

Solids (particle theory) Particles arranged in a regular way close together, hence definite shape and volume. The particles a packed closely and have strong forces holding them together, hence they are difficult to compress. As the particles are held closely together solids don't diffuse.

Liquids (particle theory) In liquids the particles have no regular arrangement hence a liquid has no definite shape and takes the shape of the container. Liquids particles are in contact with each other so can slide over each other hence liquids can flow. As the particle are in contact with each other in liquid they are difficult to compress. The forces between the particles are weaker than in solids so they can move more and diffuse.

Gases (particle theory) In gases the particles are far apart from each other and can move freely, hence no definite shape or no definite volume. As there is a lot of space between the particles gases can be easily compressed. As gas particles can move easily they can diffuse. There are only weak forces between the particles of a gas.

Diffusion Diffusion = the movement of particles to spread out and fill all the available space. Takes place in liquids and gases mostly. (why?) Ammonia gas (NH3) and Hydrogen Chloride gas (Hcl) diffuse and meet to form white smoke of Ammonium Chloride (NH4Cl)

Changes of State. When solids turn into liquids or liquids into solids or vice versa this is a change of state. Boiling point is the temperature at which a liquid changes to a gas throughout the liquid. Evaporation is the changing of aliquid into a gas. It can occur below the B.P. It only happens from the surface of the liquid. Use Pet. Ether to show evaporation from hand.

Changes of state Condensation is when a gas turns back into a liquid. For example. after a hot shower or bath the steam turns back into water ón the mirror. When steam from the kettle meets the cold window it turns back into water.

Changes of State Melting The melting point is the temperature at which a solid changes into a liquid. Freezing is when a liquid turns back into a solid.

Condense Freeze Melt Evaporate or boil Solid Liquid Gas

Copper - Solid

Copper - Liquid

Copper state – gas