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Democritus
Democritus and his mentor Leucippus discovered the first atom theory. They believed that everything is made of tiny things that never get deleted, they can only be moved or changed. They discovered this on Jan 1st 492 BC. Democritus thought that the things in his theory (atoms) were all invisible and exactly alike. He also thought that all matter was made up of atoms and they could not be destroyed or erased.Today we have realized that not all atoms are the same, but for BC his discoveries were -
Antoine Lavoisier
Antoine Lavoisier won a prize for figuring out a way to light the streets of Paris, discovered the role oxygen plays in combustion, and received a bachelor degree in college. He worked in geology and chemistry most of his life -
Law of conservation of mass
Established in 1789 by French Chemist Antoine Lavoisier States that mass is neither created nor destroyed in any ordinary chemical reaction. Or more simply, the mass of substances produced (products) by a chemical reaction is always equal to the mass of the reacting substances (reactants). -
Dalton's atomic theory
All matter is made of atoms. Atoms are indivisible and indestructible. 2) All atoms of a given element are identical in mass and properties 3) Compounds are formed by a combination of two or more different kinds of atoms. 4) A chemical reaction is a rearrangement of atoms. -
John Dalton
Dalton had created Dalton's Law which explains that the total pressure is equal to the sum of all the pressures of parts, which is for gases.
He had also revived the atomic theory. He was also a member of the Royal Society. He recorded and wrote Meteorological Observations and Essays on the weather conditions. He had investigated the color blindness condition, also known as Daltonism. -
Dmitri Mendeleev
Dmitri's greatest accomplishment is the stating of the Periodic Law and the Periodic Table. He knew there had to be a sequence for the elements so he spent more than 30 years coming up with a concept for the table. He was able to determine the atomic weight of each element -
Cathode Ray Tube
A cathode is a terminal or electrode at which electrons enter a system, such as an electrolytic cell or an electron tube.
A cathode ray is a stream of electrons leaving the negative electrode, or cathode, in a discharge tube (an electron tube that contains gas or vapor at low pressure), or emitted by a heated filament in certain electron tubes.
A vacuum tube is an electron tube consisting of a sealed glass or metal enclosure from which the air has been withdrawn.
A cathode ray tube or CRT is a s -
J.J. Thompson
J.J. Thomson discovered the electron. He found that the electron was a very small, negatively charged particles that are part of the atom. He also found Cathode Rays, which are beams of light that follow an electrial discharge in a high-vacuum tube. These rays are streams of particles that has the mass of about 1,000 times smaller than the atom. He then concluded that the atom was made of the Cathode Ryas and election. J.J. Thomson experimental work and creation of better equipment was the thing -
Plum Pudding Atomic Model
The plum pudding model of the atom by J. J. Thomson, who discovered the electron in 1897, was proposed in 1904 before the discovery of the atomic nucleus in order to add the electron to the atomic model. In this model, the atom is composed of electrons (which Thomson still called "corpuscles", though G. J. Stoney had proposed that atoms of electricity be called electrons in 1894[1]) surrounded by a soup of positive charge to balance the electrons' negative charges, like negatively charged "plums -
Robert Milikan
American physicist Robert A. Milikan's achievements began when he was the first to received a Ph.D from the physics department at Columbia University. He went on to win the Nobel Prize for physics for his work on the photoelectric effect and measuring the charge of the electron. He also was able to obtain the exact exact value of Planck's constant.Most famous for his oil drop experiments, in which he determined the electrical charge of the electron, he was also involved in many of the major deve -
Rutherford Model
Rutherford's model of the atom consisted of a positively charged center, known as NUCLEUS, which also contained most of the atom's mass. Around the nucleus orbited the negatively charged electrons. -
Henry Mosley
Henry Mosley discovered that atoms of each element contain a unique positive charge in their nuclei -
Bohr Planetary
Bohr's model of the atom placed the electrons in orbit at specific distances around the nucleus. This resembled the way in which the planets revolve around the sun. -
Niels Bohr
Electrons orbit the nucleus -
Gold foil experiment
Rutherford made an experiment where he shot alpha rays through gold foil and he hypothesized that the alpha rays particles would pass through the gold foil with little or no deflection. -
Erwin Schrodinger
The Bohr model was a one-dimensional model that used one quantum number to describe the distribution of electrons in the atom. -
Quantum Mechanical Model
The Atomic Model in Which Electrons are treated as waves is called the wave mechanical model of the atom. -
Ernest Rutherford
His atomic theory describing the atom as having a central positive nucleus surrounded by negative orbiting electrons. This model suggested that most of the mass of the atom was contained in the small nucleus, and that the rest of the atom was mostly empty space -
James Chadwick
Sir James Chadwick is a very honored scientist. His most famous and exciting discovery was the discovery of the neutron in 1932. He also succeeded in taking apart the atom, which led to the development of the Atomic Bomb, which was used at the end of WWII. The discovery of the neutron not only benefitted him, but it led other scientists to figure out the complete diagram of the atom. -
Electron Cloud Model
In chemistry and nuclear physics, the electron cloud is a way to describe where electrons are when they go around the nucleus of an atom. The electron cloud model is different from the older model by Niels Bohr. Bohr talked about electrons going around the nucleus in a fixed circle, the same way that planets go around the Sun. The electron cloud model says that we can not know exactly where an electron is, but the electrons are more likely to be in specific areas of an atom. It is the most mode
