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Arts and Crafts unit on animals for primary made by C.E.I.P. José Ortega Valderrama.

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ACTIVITIES FOR THE P.I.L.C. (I. E. S. M.F. QUINTILIANO, CALAHORRA)

Read the text and answer the questions at the end of each paragraph:

J.J. Thomson was the first man to discover electrons, while he was working with cathode rays in 1897. He realized they had a negative charge, unlike protons (positive) and neutrons (no charge). Thomson created the plum pudding model, which stated that an atom was like plum pudding: the dried fruit (electrons) were stuck in a mass of pudding (protons).

In 1909 a scientist named Ernest Rutherford used the Rutherford Experiment to prove that electrons are very small compared to protons and neutrons. Rutherford took a photo plate and surrounded it with gold foil, and then shot alpha particles at it. Many of the particles went through the gold foil, which proved that atoms are mostly empty space. Electrons are so small they make up only 1% of an atom´s mass.

Ernest Rutherford in 1910, shortly before he won the Nobel Prize for physics

In 1913, Niels Bohr introduced the Bohr model. This model showed that electrons orbit the nucleus in fixed circular orbits. This was more accurate than the Rutherford model. However, it was still not completely right. Improvements to the Bohr model have been made since it was first introduced.

QUESTIONS:

1.- Where were the electrons in the Thomson Model?

2.  Were there orbits?

3. What was new in the Rutherford Model ?

Structure and parts

The atom is made up of three main particles; the proton, the neutron and the electron. The isotope of Hydrogen Hydrogen-1 has no neutrons, and a positive hydrogen ion has no electrons. These are the only known exceptions, all other atoms have at least one proton, neutron and electron each.

Electrons are by far the smallest of the three, their mass and size is too small to be measured using current technology. They have a negative charge. Protons and neutrons are similar sizes. Protons are positively charged and neutrons have no charge. Most atoms have a neutral charge; because the number of protons (positive) and electrons (negative) are the same, the charges balance out to zero. However in ions (different number of electrons) this is not always the case and they can have a positive or a negative charge. Protons and Neutrons are made out of quarks, of two types; up quarks and down quarks. A proton is made of two up quarks and one down quark and a neutron is made of two down quarks and one up quark.

The nucleus is in the middle of an atom. It is made up of protons and neutrons. Usually in nature two things with the same charge repel or shoot away from each other. So for a long time it was a mystery to scientists how the positively charged protons in the nucleus stayed together. They solved this by finding a particle called a Gluon. Its name comes from the word glue as Gluons act like atomic glue, sticking the protons together using the strong nuclear force. It is this force which also holds the quarks together that make up the protons and neutrons.

A diagram showing the main difficulty in nuclear fusion, the fact that protons, which have positive charges, repel each other when forced together.

The number of neutrons in relation to protons defines whether the nucleus is stable or goes through radioactive decay. When there are too many neutrons or protons, the atom tries to make the numbers the same by getting rid of the extra particles. It does this by emitting radiation in the form of alpha, beta or gamma decay.^[10] Nuclei can change through other means too. Nuclear fission is when the Nucleus splits into two smaller nuclei, releasing a lot of stored energy. This release energy is what makes nuclear fission useful for making bombs and electricity, in the form of nuclear power. The other way nuclei can change is through nuclear fusion, when two nuclei join together, or fuse, to make a heavier nucleus. This process requires extreme amounts of energy in order to overcome the electrostatic repulsion between the protons, as they have the same charge. Such high energies are most commonly found in stars like our Sun, which fuses Hydrodgen for fuel.

QUESTIONS:

1.- How is the charge of protons?

Labor Force: everyone in the economy who is willing and able to work

Unemployment occurs when a person is available and willing to work but currently without work.

Ø Frictional unemployment

Occurs when a worker moves from one job to another. While he searches for a job he is experiencing frictional unemployment. Frictional unemployment is always present in an economy

Ø Cyclical or Keynesian unemployment

Cyclical or Keynesian unemployment, occurs when there is not enough aggregate demand in the economy. It gets its name because it varies with the business cycle, though it can also be persistent, as during the Great Depression of the 1930s. This is caused by a business cycle recession

Ø Structural unemployment

Structural unemployment involves a mismatch between the sufficiently skilled workers looking for jobs and the vacancies available.

Ø Seasonal unemployment

May be seen as a kind of structural unemployment, since it is a type of unemployment that is linked to certain kinds of jobs (construction work, migratory farm work). The most-cited official unemployment measures erase this kind of unemployment from the statistics using "seasonal adjustment" techniques

The gross domestic product (GDP)) is a basic measure of a country's overall economic output. It is the market value of all final goods and services made within the borders of a country in a year. It

The expenditure method:

GDP = private consumption + gross investment + government spending + (exports − imports)