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UNIT 6. MATTER AND ENERGY.

SCIENCE 5.

CONTENTS: 1.– Matter: .- General properties: mass, volumen. .- Specific properties: density, hardness, solubility... 2.a.- States of matter: solid, liquid, gas. 2.b.– Phase transition: evaporation, condensation... 3.- Pure substances and mixtures (separation processes). 4.- Chemical reactions: oxidation, combustion, fermentation 5.- Forces produce deformation and movement. Gravity. 6.– Velocity.

MATTER is anything that has a mass and volume and occupies a space .

1.– MATTER: is anything that has a mass (it’s posible to be weighted) and occupies a space (volume). GENERAL PROPERTIES: a.- Mass: is the amount of matter in an object. We can measure the mass with a scale. The unit of mass is the gram (g.) . 1 kg = 1000 g. 1 tonne = 1000 kg.

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We can measure the mass with a scale.

b.- Volume: is the space that a substance or body occupies or contains. We can measure the volume of a solid putting into a graduated container with a liquid, and watching the increasing of the liquid level. The unit of volume is the litre (l.) 1 cm3 = 1000 ml = 1 l. 1000 litres = 1 m3 2

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MASS: is the amount of matter in an object. VOLUME: is the space that a substance or body occupies or contains.

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We can measure the volume with a graduated container.

SPECIFIC PROPERTIES: .– Density: is the mass of an object divided by its volume. There are substances with a great mass in a small volumen (iron), we can say that iron is very dense, but there are others like air, oil, wood.… that are less dense.

The unit of density is kg/m3 or g/cm3.

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d = _Mass (m) Volume (V) 6

.– Buoyancy: is the upward force exerted by a fluid that opposes the weight of an immersed object Wood floats because is less dense than water.

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.- Hardness: is the ressistance of a substance to being scratched. .– Solubility: is the ability for a substance (the solute), to dissolve in a solvent.

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Parts of a Solution: Solute and Solvent.

USEFUL WORDS: .– matter .– mass .– buoyancy .– hardness

.– volume .– solubility

.– density .– thermal conductivity

Buoyancy

2.1.– STATE OF MATTER: We can find matter in thre types of states:

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STATE OF MATTER: solids, liquids and gases.

a.- Solids have a fixed volume and shape, with particles close together and fixed into place. b.- Liquids have a fixed volume, but its shape are adapted to the containers. Particles are still close together but move freely.

c.- Gases have variable volume and shape, adapting to the container. Particles aren’t close and move freely. 9

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2.2.- PHASE TRANSITIONS: Phase transitions describe changes between solids, liquids and gases. These changes depend on the increasing or decreasing of temperature. Temperature is the numerical measure of hot or cold from a thing or substance. The unit of temperature is degree ºC, ºF.

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TEMPERATURE INCREASES

.- Temperature increases: .-Melting: change of a substance from solid to liquid. Melting point of water is 0ºC .- Evaporation: changes from the surface of a liquid into a gas. Boiling is when the vaporization occurs within the entire mass of the liquid. Boiling point of water is 100ºC .- Temperature decreases: .- Condensation: is the change of a substance from a gas into a liquid. Water vapour condenses into liquid after making contact with the surface of a cold bottle. .- Freezing: is the change from a liquid into a solid when the temperature is below its freezing point. Water becomes ice when temperature is 0ºC.

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TEMPERATURE DECREASES

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Gas: clouds. Liquid: water Solid: ice

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3.– PURE SUBSTANCES AND MIXTURES: We can find substances in nature in different ways: .– Pure substances are substances formed by only one type of matter (eg. Oxygen, gold, water...). .– Mixtures are subtances formed by two or more types of matter together (eg. Salted water, granite, foods... ) USEFUL WORDS: .– solid .– liquid .– degree .– melting point – freezing .– condensation

Pure substance: gold

.– gas .– evaporation .– Mixture

Mixture: chocolate and milk.

.– temperature .– boiling point .– Pure substance

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3.1.– MIXTURES: TYPES. We can find two types of mixtures:

a.– Heterogeneous mixtures: we can see the different types of matter because they don’t have an uniform composition ( e.g.: a rock) b.– Homogeneous mixtures: we can’t see the different types of matter because they have an uniform composition (e.g.: salted water, air…) 20

We can find pure substances and mixtures. There are heterogeneous and homogeneous mixtures. 3.2MIXTURES: SEPARATION PROCESSES. 1.- Filtration: is a method of separating a solid from a liquid, to remove solid particles (e.g.: mixture of sand and water).

Homogeneous mixture: salted water

Heterogeneous mixture: oil and water

We use filtration to make coffee.

2.- Evaporation: is a method to heat the mixture until the solvent evaporates (turns into gas) leaving behind the solid residue (e.g.: extraction of salt from seawater)

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Evaporation to extract salt

3.- Magnetic separation is a method for separating mixtures when one of the solid has magnetic properties (e.g.: mixture of iron and another solid).

There are different processes to separate mixtures like: filtration, evaporation, magnetic separation... 4.- CHEMICAL REACTIONS. The most important chemical reactions are: 4.1.- Oxidation is a chemical reaction in which a substance combines with oxygen. Example: an object made of iron combines with the oxygen from the air (in a wet environment) and get rusted.

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Magnetic separation is used to separate iron pieces from sand.

A chemical reaction is a process that transforms some chemical substances into other different substances called products. Types: oxidation, combustión & fermentation

4.2.– Combustion is a very quick oxidation process, between a fuel (wood, paper…) and oxygen. Every combustion produces heat and light. 24

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Oxidation of iron

USEFUL WORDS: .– heterogeneous mixture .– homogeneous mixture .– filtration .– evaporation .– magnetic separation .– chemical reaction .– oxidation .– combustión .– fermentation

combustion

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Oxidation of fruit (on the right)

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4.3.– Fermentation

is a process that converts sugar to other substances like gases (CO2, alcohol… It is made by yeast, bacteria... It is used to produce alcoholic drinks (beer, wine…) and dairy pruducts (yogourt), bread... Beer and bread, are examples of fermentation in food. 27

5.– FORCES PRODUCE DEFORMATIONS AND MOVEMENT. 5.1.– FORCE: There are forces that produce movement and others produce deformations on objects. A.– Forces that make deformations: When a force acts on an object, it can produce some deformations on its shape. So we divide objects in: 1.– Elastic objects change their shape only when the force is acting. (e.g.: rubber, spring…). 2.– Plastic objects change their shape, and don’t get the previous shape after the force has finished (e.g.: plasticine…) 3.– Rigid objects don’t change the shape, the force breaks it (e.g.: eggs, mirror…) 28

A force can change the position or movement of an object, or makes a deformation on it. Elastic objects:

Rubber ball

spring

Rigid objects:

Plastic objects:

Plasticine

Clay

Broken mirrow

Breaking an egg shell

There are three types of objects depending on the deformation by forces: Elastic, plastic and rigid. B.– Forces that produce changes in position or movement: 1.– Contact forces: when an object produce a force to another object by contact (touching the other object). 2.– Non-contact forces: when an object interacts with another object without touching it (magnetism, gravity). Gravity is the force of attraction between every object and the Earth. (e.g.: an object falling to the floor). Contact force: people pushing a car.

Gravity is the force of attraction between every object and the Earth.

Sir Isaac Newton discovered gravity.

USEFUL WORDS: .– elastic objects .– contact forces

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.– plastic objects .– rigid objects .– non-contact forces .– gravity

Gravity attracts objects to the centre of the Earth, from every place. The force of attraction depends on the mass of the Earth and the object’s.

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Gravity attracks objects from everyplace.

The quantity of this force is called weight. So the weight of and object is different on the Earth than on the surface of the Moon.

5.-VELOCITY or SPEED: There are lots of forces that produce movement on objects (a car engine moves a car, a man moves a bicycle, the raquet makes a force and moves the tennis ball…). So the forces move objects a distance during a time. The relation between distance (space) and the time is called “velocity” or “speed”.

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The woman moves the bike.

The car engine moves the car.

Imagine we apply a force to a toy car, and it moves 1 metre in 1 second. Its velocity (or speed) is 1 metre per second. Velocity = Distance Time

1 metre

V = 1 metre = 1m/s 1 second 33

We can measure velocity (or speed) in different units. The most common ones are:

Metres per second

When an object is moved: Velocity is the distance, divided by the time it spends. Velocity = Distance Time

m/s

Kilometres per hour km/h 34

Imagine a car goes from Madrid to Córdoba. The distance between these two cities is 400 km. The car spends 4 hours during the trip. Let’s calculate its speed. Remember: Velocity is the distance divided by the time. Velocity = 400 kilometres 4 hours

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100 km/h

Trip from Madrid to Córdoba 400 km

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USEFUL WORDS: .– gravity .– weight .– distance .– time

.– velocity/speed

Matter and energy
Matter and energy

Matter and energy. Unit for Primary. 5th level.