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unit 61st ESO

What we are formed?

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NTeacher: Miss Eva Pla

The matter

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Matter: He is all that one than the bodies, everything are formed what it has mass, it occupies a place in the space and exists in the Universe.

Mass: It is the amount of matter that a body owns. The matter appears in diverse states: gaseous solid liquid, that interchanges by means of diverse physical processes and is invariable.

Substance: They are the diverse classes of matter. It can be pure or it mixes of several substances.

Pure substance: It is a matter of fixed composition and invariable, it can simple or be composed: ­ Simple pure Substance is all the chemical elements. ­ Compound pure Substance is all the chemical compounds.

The matter is an atom aggregation. Atom, by its etymology, is as much as indivisible. We understand by atom like the smaller portion of an element that conserves the properties of this element.Leucipo and its disciple Democritus were first in teaching that the matter is discontinuous, that is to say, that cannot be divided indefinitely. The molecule is the atom association in fixed and invariable proportion. A pure substance is all she trained by a single type of molecules. The atoms have a very great energy in their interior, that is shown in the nuclear reactions. Otto Hahn and Strassmann used slow neutrons in the bombing of 92U238. Phase accompanied by great loosening of energy had been verified the uranium fission. It was the principle of the atomic bomb (1939) and of the nuclear power.

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General properties:

give a characteristic of the substance, but their values do not allow to differentiate substances from others, like the mass and the volume, the temperature, the form.

Specific properties:are those that allow us to differentiate substances from others, like for example the density, the fusion point and boiling and the conductivity.

Magnitude:

is a property or attribute of an object or physical system which can be assigned different values as a result of quantitative measurement.

S.I. : International System

also called the International Measurement System, is the name given to the System of Units that is used in all countries

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Mass

It is the property of the bodies indicates the amount of matter they contain, and is unchanged.It is in kilograms (kg)

We don't have to confuse the mass with the weight, the last one depends on the gravity

W = m · g

m = Wg

Earth gravity =9.8 m/s2

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Volume

Is the amount of space that a body occupies.The S.I. unit is the m3

To calculate the volume of an irregular body, we can do with a test tube:

this volume displaced is equal to the volume of irregular body

kl Hl Dal l dl cl ml

m3 dm3 cm3

Tm Kg Hg Dag g

x10 x10 x10:10:10:10

This equivalence is, always and when we speak of distilled water, but we must apply the density if it's another substance.

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Density

Is the mass in an specific volumen (quotient between mass and volume)

d = mv unit: kg/m3

the density of water is greater than that of men, for this reason, it is floating.

water density > man density

in the picture you could see a video about floating

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Exercice:

We are in a room with the following dimensions: 7m large, 4m wide and 3m high. a) Express the mass in kg of water into the roomb) Express the mass in kg of air into the room

7m

4m

3mV = 7m ∙ 4m ∙ 3m = 84 m3

84 m3 ∙a) 1 m3

1000 dm3

1 dm3

1 kg= 84000 Kg water

84 m3 air ∙b) 1.18 = 99.12 Kg air

air density: 1.18 kg/m3

m3

Kg

In order to know the air mass we need the density of the air, d = m / v, because is the only way we can make the equivalence between mass and volume.In the case of water it is the same but you must know that the density of water is 1kg/m3

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ATOM

We understand the atom as the smallest portion of an element that retains the properties of that element.

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Atoms are composed of smaller particles called protons, neutrons and electrons. These particles are found in two distinct areas: the nucleus and the crust.The core occupies the central part of the atom, where they are located fixed protons and neutrons.The crust occupies the outside of the atom. Here are the electrons that orbit the nucleus, as in a planetary system, therefore, with large empty spaces.Rutherford was in 1911, who with their experience, established the nuclear model of the atom. According to him, every atom consists of nucleus and cortex. The centrifugal force of the electrons is balanced by the electrostatic attraction exerted by the protons in the nucleus. That justifies the stability of the Rutherford atom.

electron (­)crust:

neutronnucleus:

proton(+)nucleus:

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H

O

H

H2O1 oxygen2 hydrogens

Protons have a positive electrical chargeNeutrons carry no charge; they are neutralElectrons carry a negative electrical charge

Atomic number = Nº of protons = Nº of electrons

Mass number = Nº of protons + Nº of neutrons

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Keeping the following charts:

Na (atomic number = 11 / mass number = 23)

Al (atomic number = 13 / mass number = 27)

S (atomic number = 16 / mass number = 32)

Complete the following table:

atom nucleus crust

protones neutrones electrones

Na

Al

S

Exercice:

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A chemic element is a substance made up of only one type of atom.

The elements are arranged in a particular way on a table: PERIODIC TABLE OF THE ELEMENTS. This table puts the 118 items as the number of protons contained in each atom.

This table arranges the elements in horizontal rows called periods and vertical columns called groups. The groups are often numbered using the old Roman numerals.

All the elements locked in the same columns and files have similar properties, is important for the behavior of the atoms..

http://www.webelements.com/

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In the Periodic Table we find two big groups:

Metals have many uses in everyday life. Buildings and cars contain a great deal of metal. And all metals behave in the same way. Most metals have properties in common:

¬ They are strong.¬ They are malleable (they can be hammered into shapes).¬ They are ductile (they can be drawn out into long wires). This is very useful when turning copper into electrical wires¬ They are sonorous (they make a ringing sound when hit).¬ They are good thermal conductors (they are good conductors of heat).¬ They are good conductors of electricity (all metals conduct electricity but some do it better than others for example copper is a good electricity conductor).

Exceptions:

¬ Iron is magnetic¬ Lithium, sodium and potassium are so soft that they can be cut with a knife¬ Mercury is the only metal that is a liquid at room temperature¬ Aluminium is very light but is still very strong

The 21 non metals vary a great deal in their physical appearance and in many respects are the opposite of metals:

¬ They are not strong. ¬ They are not sonorous.¬ They are not ductile. ¬ They are not malleable.¬ They are poor thermal conductors.¬ They are poor conductors of electricity: graphite, which is a form of carbon, is an exception and is a good conductor of electricity.¬ They are light because they have low densities.

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Substances can be mixtures, compounds or elements. If a piece of magnesium is burned in a Bunsen flame, a white powder is produced. This white powder is called magnesium oxide. It has been made by the magnesium combining with oxygen from the air. The magnesium oxide is a compound and it is a completely new material and different from the magnesium and the oxygen.

Element: a substance that is made up of only one type of atom is called an element. Sodium is an element. It is made up of nothing but sodium atoms.

Compound is a pure material made up of two or more elements chemically combined for example:Water which is made up of hydrogen and oxygenCommon salt made up of sodium and chlorineAlcohol made up of carbon, hydrogen and oxygen. Chalk made up of calcium, carbon and oxygen

A molecule is the smallest part of a compound that can exist. It is made up of two or more atoms joined together. A compound is written as a formula. A chemical formula is a set of symbols and numbers. The symbols tell what elements are present in the compound. The numbers give the ratio in which the atoms of different elements are present: Water H2O.

Mixture is a collection of different substances that are not connected in any special way. In a mixture the materials do not combine, they are still present in the mixture in their original form.

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Physical and chemical chanages:

Physical changes are temporary and can be easily reversed. For example water can be turned into ice and back again. If we add salt to water we can evaporate the water and get the salt back again. So, a physical change is one which can be reversed by changing the conditions and in which no new substance is formed.: ­ Different states of matter (solid, liquid, gas) ­ mixture (salt + water: because when the water is evaporated we obtain the salt)

A chemical change is brought about by a chemical reaction. The simplest form of chemical reaction is when two elements react together to form a compound. Chemical changes are related to the law of “conservation of mass” which states that matter is neither created nor destroyed in a chemical reaction. This means that the total mass of all the materials produced in a chemical reaction (the products) must equal the total mass of all the material that reacted together to make the reaction (reactants).­ Corrosion­ Oxidation

differences between chemical and physical change

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Changes of state:

Water (H2O)>100ºC

>0ºC< 100ºC<0ºC

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