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LAVOISIER'S MASS CONSERVATION ACT
(1743 - 1794) Heated a piece of tin in a closed container with a certain amount of air. The piece of metal gained weight because its surface had rusted, but Lavoisier found that the weight of the closed ensemble had not changed. He interpreted the tin weight gain because part of the enclosed air had passed into the metal chunk. -
Proust's Defined Proportions Act
(1754–1826) The French scientist Louis Proust studied the proportions in which certain elements were joined to produce a compound.
It found that, for example, sulfide always contained 86.5% lead and 13.5% sulphur regardless of the quantity, where it came from or how it is obtained. -
Dalton´s model
Matter is discontinuous and made up of atoms.
The elements are made up of discrete particles of matter (atoms) wich are indivisible and inalterable.
All the atoms of a single element are the sime size and mass, but are different to the atoms. -
X-rays
Wilhem K. Roentgen, German physicist, discovered some rays he called X-rays, for example its unknown nature and that were characterized by:
- Do not deviate from a plate electrically charged (not had loads)
- Being able to traverse Materials. -
Radioactivity
Henri Becquerel observed a new type of radiation. More ahead, his disciple Marie Curie suggested the name radioactivity to describe the issuance of radiation from some Substances. -
Thomsom atomic model
( 1897 - 1904) Thomson proposed an atom model made up of negative electrically charged particles (electrons], immersed in a positive electrically charged fluid, which resulted in an electrically neutral atom. • Matter is electrically Neutral. • Electrons came out of the atoms by subjecting them to intense electrical potentials. • The electrons were identical for all types of atoms. This model explained the known phenomena it is also known as the plumcake -
Discovery of electro (J.J. Thomson)
Cathode rays are made up of particles of matter that are much smaller than an atom and have a negative electric charge. -
Rutherford's experiment
New Zealand physicist conducted an experiment in which he bombarded with alpha particles, which have positive electrical charge, a very thin sheet of gold. New Zealand physicist Ernest Rutherford.
Rutherford proposed nuclear atomic model, which places most of the
atom mass concentrated in a very small área (against which the deflected particles collided). This model assumes that the rest of the atom is practically empty. -
Bohr model
Niels Bohr, a Danish physicist, proposed a new model that aimed to correct the shortcomings of the Rutherford model:
- Electrons are distributed in layers electronic, spinning in well defined orbits and Stable.
- In such orbits the electron does not absorb or emit energy, but it can jump from one to the other, absorbing or emitting energy in that case.
