1

Le Science in pilloleO

Appunti di scienze

A cura delle insegnanti Allida De Candido e Cristiana Ziraldo

Summary

Home

I.P.S.I.A “ Zanussi” di Pordenone

2

States of matter

 

The students are introduced to a unit involving States of Matter

Objective

•to known the three states of matter (solid, liquid and gas);

•to list the general properties of each state;

•to describe them in terms of shape and volume;

•to list everyday examples of each state;

Subject Area: Science

Class Level and Course Title: first Class / Science of Earth

Unit of Study: States of Matter

Summary

Home

3

Matter is anything that takes up space and has weightMatter is anything that takes up space and has mass or weight. Matter exists in three forms or states - solid, liquid and gas.

Solids can be

soft or hard

Can you think of something on the Earth that is hard?RocksMinerals

Liquids can be

On the Earth

Gas can be

•(

Summary

Home

Forms of matter

4

Solid state

• Particles in a solid have fixed position.•They are close together.•If they are positioned in a regular structure they may form crystals.•The forces holding them in position are strong, so solids have their own shape.

•At 0 K (-273°C) the particles are stationary.•At temperature above 0 K the particles vibrate but cannot move from their positions.•As the temperature increases the vibrations become more energetic.

5

Summary

Home

Liquid state

Liquids take the shape of the container into which they are put.

Particles in a liquid are still fairly close together.

The forces between particles are not as strong as in a solid and allow groups of particles to slide over each other. This is why liquids can flow.

Particles in a liquid therefore do not have a fixed position.

Liquids do not have a shape of their own.

They take the shape of the container into which they are put.

These groups of particles move around slowly.

Because the liquid particles move around slowly the dye gradually mixed with the water.

6

Gas state •The distances between gas are relatively large.•Therefore they are almost completely free of forces and so spread out and fill any container into which they are placed.•They are moving around at high speeds (approx. 500 m/sec at room temperature).• Gases diffuse (spread out and mix) more quickly than liquids.•The directions in which they move have no pattern: they are random motions (speed and direction).•The gas particles inside this container are continually bouncing off the sides. It is these collisions with the sides of the container that create the pressure inside the container.

Summary

Home

7

Summary

Home

What affects the pressure in a gas

There are several factors that will affects the size of the pressure in a gas.

VolumeIf more gas particles are pushed into the container there will be more frequent collisions and so the pressure will increase.

MassIf the volume of the container is decreased, the particles will have less distance to travel between collisions.

There will therefore be more collisions per second, i.e. the pressure will increase.

TemperatureIf the temperature of a gas is increased its particles will move faster, there will be more collisions each second and there will again be an increase in pressure.

8

Summary

Home

SOLID

Definite volume

and shape

LIQUID

Definite volume, no

definite shape

GAS

No definitevolume or shape

To sum up

Attributes of matter

9

Summary

Home

Changes of states

In the daily lives, there are a variety of matter in the different states.

Objectives

To be able to classify and describe the changes of state

To know haw matter changes and what causes matter to change

10

Changes of State of Matter

There are different changes that can take place. Water, for example, can change from water to ice, which is called freezing. Freezing is what happens when a liquid changes to a solid.

Water can change from ice to water, which is called melting. Melting is what happens when a solid changes to a liquid.

*

Summary

Home

Freezing

Melting

11

Water can also change from a water to steam, which is called evaporation. Evaporation is what happens when a liquid changes to a gas. Water can change from steam back to water, which is called condensation. Condensation occurs when gas changes into a liquid.

Water Gas

There are some substances which can go from being a solid, directly to the gas state, which is called sublimation. Solid carbon dioxide, commonly known as Dry Ice, bypasses the liquid state altogether when it changes to a gas.

Summary

Home

evaporation

condensation

12

The last change of state is matter going from a gas, directly to the solid state, which is called deposition. Water vapours in the air during winter fall in the form of snow,

Solid Gas

Summary

Home

Sublimation

Deposition

13

Energy Energy is either lost or gained during a change of state.

* When energy is applied to a solid, the tightly packed particles of matter begin to move around, flowing over each other. The result is the movement of liquid. The shape becomes indefinite. The volume, however, does not change, because the particles are still part of one another.

* When energy is applied to a liquid, the particles that make up a liquid, begin to move about so rapidly, that they can no longer hold themselves together. The result is the movement of a gas. The shape is indefinite, and the volume becomes indefinite.

•The reverse happens to gas when energy is taken away. Water vapour, for example begins to liquefy as it cools. Remember the cool mornings when fog is dense and close to the ground? What happens? Dewdrops form. The water vapours in the air cool to form liquid drops on grass.

* When energy is taken away from liquid, the particles in the liquid slow down to low movement. The resulting solid, has definite shape and definite volume.

Summary

Home

Cause of changes

14

Summary

Home

Cooling

To sum up

Heating

Deposition?=brinamento

freezing condensation

sublimation

melting evaporation

15

1) When a solid changes into a liquid, it is called ...... a) vaporization b) melting c) evaporation

2) When a solid changes directly into a gas, it is called...... a) sublimation b) evaporation

3) When a gas changes into a liquid, it is called ......a) solidification b) meltingc) condensation

4) Matter in a solid state has . . . . . volume and . . . . . . shape.

a) ____ no definite _____ no definite b) ____ a definite ______ a definite c) ____ a definite ______ no definite

5) The states of matter are the following: solids, liquids, gases, plastics.

a) True b) False

6) States are also known as ? a) phases b) phrases c) frases

7) Which phase of matter does not take the shape of the container it is in?

a) solid b) liquid

Summary

Home

Test

16

8) Liquids are hard to compress. Gases are easy to compress.

a) True b) False

9) When solids reach their melting point they become ......

a) liquids b) gases

10) What happens when a gas reaches condensation point?

a) it becomes a solidb) it becomes a liquid

11) What is evaporation? a) When liquids turn into vapour b) When solids turn into vapour

12) What state / phase can fit into any container of any size and any shape?

a) a gas b) solid c) liquid and solid

13) Gas and vapour means the same. a) True

b) False

14) Which state can hold their own shape? a) a solid b) a liquid c) a gas

Summary

Home

17

15) Which state of matter resists very strongly if you try to change its shape?

a) gas b) solid

16) When a liquid changes into a solid, it is called ......

a) melting b) freezing c) condensation

17) Solidification is when a gas changes into a solid. a) true b) false

18) Matter in a ...... has a ...... volume and ...... shape. a) gaseous state ___ no definite ___ no definiteb) liquid state _____ no definite ___ definitec) solid state _____ no definite ___ no definite

19) When water freezes or when water becomes a vapour is it still the substance: water?

a) yes b) no

20) Pick the correct statement: a)Solids become gases at their melting points b)Solids become liquids at their melting points

Summary

Home