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Physics & Chemistry 2ESO, The tidal flow or the movement of the waves…
Physics & Chemistry 2ESO
U1: Matter
A) ATOMS AND MOLECULES
DEFINITIONS
MATTER: everything that has mass and takes up space
ATOM: the smallest particle in which matter can be split without losing its properties.
MOLECULE: group of two or moreatoms joined together by bonds.
BOHR ATOMIC MODEL
Inside an atom there are three type of particles: protons, neutrons and electrons. Every element has its own atomic number (Z). The atomic number is the number of protons in an atom of this element.
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C) ISOTOPES AND IONS
ISOTOPES are variations of chemical elements that have the same number of protons but different numbers of neutrons.
An ion is a molecule or atom that has a positive or negative electrical charge. That is, an ion is an atom whose electrical charge is not neutral.
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E) SOLUTIONS
When we speak of solutions we usually mean a homogeneous mixture of a liquid (very often water) and a solid.
However, a solution is any homogeneous mixture.
When salt is added to water, the salt disappears from view. The salt is still there. The salt has dissolved and formed a
solution. If more and more salt is added to water, a point is reached where no more salt will dissolve, this solution is called saturated solution.
A substance that dissolves is said to be soluble and a substance that does not dissolve is said to be insoluble. In a solution the soluble substance is called solute and the liquid solvent. When a solid dissolves, the regular arrangement of particles breaks down and the particles spread throughout the solution. Solids dissolve faster in hot water because the particles have more energy and move faster.
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H) PHYSICAL QUANTITIES
The present SI has seven base quantities: time, length, mass, electric current, thermodynamic temperature, amount of substance, and luminous intensity.
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U2: Chemical Reactions
- CHEMICAL FORMULA AND CHEMICAL REACTIONS
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The reactants are the substances present before the reaction takes place
(initial substances) and the products are the substances produced in the reaction
(final substances).
REACTIONS
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Neutralisation is the reaction between an acid and a base.
Carbonates are chemical compounds which are bases. An example of a
carbonate is calcium carbonate. Limescale, limestone, chalk and marble contain
calcium carbonate. When an acid is added to a carbonate, a neutralisation reaction
occurs and carbon dioxide gas is produced:
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Burning is also called combustion. Burning or combustion is the reaction between
a substance and oxygen, in this reaction an oxide is formed.
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U4: Forces and Movement
Forces are measured in newtons (the symbol is N). A force is drawn as a straightline with an arrow at the end. The arrow shows the direction in which the force is ACTING.
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Force is a phenomenon that modifies the movement of a body or deforms it. Forces can be represented by vectors, since they have magnitude and direction. The concept of force should not be confused with effort or energy.
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- Balanced and unbalanced forces
If two equal forces are applied to an object in opposite directions the two forcescancel each other out and are called balanced forces. When the forces acting on an object are balanced the net force acting on the object is 0. We can also say that the object is in equilibrium.
When all the forces acting on an object do not cancel out, we say they are not balanced and they are called unbalanced forces. When the forces acting on an object are not balanced the net force is not 0.
U5: Energy 
Energy is the ability to make something happen.
The world is made up of matter and energy. Matter has mass and takes up space.
Energy has no mass and it does not take up any space. We cannot see energy, we cannot touch it with our hands; but, it is all around us. The energy obtained from
burning petrol is enough to move a car.
The SI unit of energy is the joule (J). Another unit of energy is the calorie.
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Energy can be transformed from one type to another. This change in the
form of energy is called an energy transfer.
The wax in a candle contains chemical energy. When the candle burns the chemical
energy is transformed into heat energy and light. This energy transfer can be shown
using an energy flow diagram:
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The law of conservation of energy states:
Energy cannot be created nor destroyed; it can only be transformed from one type
to another.
This law means that in all energy transfers the total amount of energy at the end
is equal to the energy at the start.
ENERGY DOURCES
NON-RENEWABLE
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Coal, mineral oil and natural gas are called fossil fuels. They were formed in similar
ways over millions of years.
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RENEWABLE
Wind
wind moves the blades of a wind turbine which turns a generator. Wind
turbines are found in wind farms.
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Running water
Water stored in a reservoir flows down through a pipe to drive
turbines which turn a generator. This is called hydro-electricity.
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Geothermal
Steam can be produced using the heat inside the Earth; this
steam drives turbines which turn a generator.
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