The history of atomic structure, what is the history of the development of atomic structure models

History of atomic research.

In 400 BC, the Greek philosopher Democritus proposed the concept of the atom.

In 1803, Dalton proposed the atomic theory.

In 1833, Faraday proposed the law of electrolysis, which implied that atoms were charged and that electricity could exist as discontinuous particles.

In 1874 Stone suggested that the particles exchanged in the electrolysis process were called electrons.

In 1879, Crookes discovered cathode rays from a discharge tube (a vacuum tube with high voltage and low pressure).

In 1886, Goldstein discovered anode rays from a discharge tube.

In 1897, Thomson confirmed the high-speed flow of electrons released from cathode rays, i.e., cathode materials, and measured the charge-to-mass ratio of electrons. e m = 108 coulomb grams.

In 1909, Milikan's oil drop experiment measured the charge of electrons and strengthened the concept that electrons are particles.

In 1911, Rashford's particle scattering experiment found that the atom has a nucleus, and the nucleus is positively charged, extremely massive, and very small. The strip uses (particles (i.e., helium nuclei) to hit the gold leaf, and it is found that most of the particles pass straight through the gold leaf, a few of which are deflected at a large angle, and even a very few are reversed (1 in 100,000).

In 1913, Mosler established the concept of atomic order from the relationship between the wavelengths of the X-ray spectrum.

In 1913, Thomson's mass spectrometer measured the mass and discovered the isotope.

In 1919, the proton was discovered in Lasefaux. It uses particles to hit nitrogen nuclei and discovers protons, and then uses particles to impact the nuclei (b), fluorine (f), aluminum (a1), phosphorus (p) nuclei and so on to produce protons, so it is inferred that protons are common components of the nuclei of elements.

In 1932, Chadik discovered the neutron. It uses particles to strike the beryllium nucleus.

In 1935, Hideki Yukawa discovered the meson theory, which stabilized the nucleus of an atom.

History of the development of atomic structure.

Presented by. Experimental basis.

Conclusion. Doarthon (1803).

According to the law of conservation of mass and fixed ratio, the atomic theory was proposed.

An atom is the smallest unit.

Tang Musheng (1897).

Cathode ray tube experiment.

Discover electrons. Negative rays are the flow of electrons.

The deflection of the cathode rays to the positive electrode in the electric field is independent of the type of gas in the tube and the electrode material, and can have the same charge-to-mass ratio (

The watermelon model is proposed: the mass and positive charge are evenly distributed, and the electrons are buried in it.

Milikan (1909).

The amount of electricity measured by the oil droplet experiment.

Electron charge (e) = coulombs.

Cathode rays and oil droplet experiments determine the electron quality (

Lasseford (1911).

Particle scattering experiments.

Most of the particles pass in a straight line.

A small number of particles produce large angular deflection.

Overthrow the atomic model and build a nuclear atomic model.

Nuclear atomic model: The positively charged particles in an atom are gathered into a nucleus with most of the mass of the atom, and the electrons revolve around the nucleus.

Tang Musheng (1913).

The mass of each element was measured using a mass spectrometer.

Know the isotope species.

Rasseford (1919).

The particles hit the nitrogen nucleus.

Discover protons. Chadek (1932).

The particles hit the beryllium atoms.

Neutrons are found, and the uncharged mass of the neutron is approximately equal to the mass of the proton.

The history of the development of the atomic structure model is:First, at the beginning of the 19th century, the British scientist Dalton.

He proposed the modern atomic theory, which he believed that atoms are tiny, indivisible solid spheres.

Second, in 1911 British physicist Rutherford.

Thomson's student) proposed a model of the structure of an atom with a nucleus.

Third, in 1897, the British scientist Thomson discovered the electron, and in 1904, he proposed a "raisin bread-style" atomic structure model.

Fourth, Austria.

Physicist Schrödinger proposed the electron cloud model (probability theory), which is the modern quantum mechanics.

Atomic model. V. Denmark in 1913.

Physicist Bohr (a student of Rutherford) introduced quantum theory.

point of view, a model of the atomic structure of the movement of electrons in a certain orbit is proposed.

Theory of the atomic structure model:1.Atoms are particles that cannot be divided.

2.Atoms of the same element are the same in various properties and masses.

3.Atoms are tiny solid spheres.

The development of atomic structure model refers to the process of discovering and proposing new atomic structure models from the first atomic structure model proposed by Dalton in 1803.

Dalton's model (1803) The atom is a hard, solid ball, British natural scientist John Dalton.

The world's first atom was proposed.

Theory:

Atoms are particles that cannot be divided.

Atoms of the same element are the same in various properties and masses.

Atoms are tiny solid spheres.

Although it was proved that this was a failed theoretical model, Dalton brought the atom from philosophy to the study of chemistry for the first time, and clarified the direction of future chemists, and chemistry really began to move from ancient alchemy.

Dalton was also hailed as the "father of modern chemistry" by later generations.

From the British chemist and physicist Dalton.

After the creation of the atomic theory, for a long time, it was believed that the atom was like a solid ball of glass that could not be smaller, and there were no more tricks in it.

Since 1869 the German scientist Hitoff discovered cathode rays.

Later, Crookes, Hertz.

Lerner, Thomson.

A large number of scientists have studied cathode rays for more than 20 years.

Eventually, Thomson.

The presence of electrons was discovered. Normally, atoms are not charged, since negative electrons can run out of atoms that are 1700 times smaller than their mass, which indicates that there is a structure inside the atom, and it also means that there are positively charged things in the atom, and they should be neutralized with the negative charge carried by the electrons, so that the atom is neutral.

The basic structure of an atom includes the nucleus and extranuclear electrons.

The nucleus includes protons and neutrons, each proton carries a positive charge of one unit, each neutron is not charged, each electron outside the nucleus carries a negative charge of one unit, and the number of protons is equal to the number of electrons outside the nucleus, so the atoms are not electrically charged.

Notes:

The number of protons in the atom and the number of electrons outside the nucleus.

The number of protons is different for each type of atom.

Not every atom contains neutrons.

Correct statement: Atoms are made up of protons, electrons, and neutrons.

Myth: Atoms must be made of protons, neutrons, and electrons.

Details:

1.Nucleus.

The nucleus is the center of an atom, and an atom has only one center. In atoms, the nucleus is small in size but has a large mass, and the mass of the atom is mainly concentrated on the nucleus. The nucleus is composed of a certain number of protons and neutrons, in which protons are positively charged, and each proton has a unit of positive charge, while neutrons are not charged, so the nucleus is positively charged, and the number of positive charges carried by the nucleus is called the nuclear charge number.

2.Extranuclear electrons.

There is a large space in the atom in which a certain number of electrons move around the nucleus at high speed. Electrons are negatively charged, and each electron carries one unit of negative charge. The mass of the electron is small, much less than the mass of the nucleus, and is usually negligible.

3.Atoms are not electrically conductive.

The number of nuclear charges = the number of protons = the number of electrons outside the nucleus, because the electric charge carried by the nucleus and the electrons in the atom is equal and the electrical properties are opposite, so the atom is not electrical.