DIFFERENCE BETWEEN J.J.THOMSON, RUTHERFORD MODEL, BOHR'S,

DIFFERENCE BETWEEN J.J.THOMSON, RUTHERFORD MODEL, BOHR’S,.

J.J.THOMSON’S MODEL(1866-1940). Thomson's discovery of the electron completely changed the way people viewed atoms. Up until the end of the 19th century, atoms were thought to be tiny solid spheres ..

In 1903, Thomson proposed a model of the atom consisting of positive and negative charges, present in equal amounts so that an atom would be electrically neutral. He proposed the atom was a sphere, but the positive and negative charges were embedded within it . Thomson's model came to be called the "plum pudding model" or "chocolate chip cookie model ". Modern scientists understand atoms consist of a nucleus of positively-charged protons and neutral neutrons, with negatively-charged electrons orbiting the nucleus. Yet, Thomson's model is important because it introduced the notion that an atom consisted of charged particles..

Interesting Facts About J.J. Thomson. Prior to Thomson's discovery of electrons, scientists believed the atom was the smallest fundamental unit of matter . Thomson called the particle he discovered 'corpuscles' rather than electrons. Thomson's master's work, Treatise on the motion of vortex rings , provides a mathematical description of William Thomson's vortex theory of atoms. He was awarded the Adams Prize in 1884. Thomson discovered the natural radioactivity of potassium in 1905 . In 1906, Thomson demonstrated a hydrogen atom had only a single electron ..

Thomson's father intended for J.J. to be an engineer, but the family did not have the funds to support the apprenticeship. So, Joseph John attended Owens College in Manchester, and then Trinity College in Cambridge, where he became a mathematical physicist. In 1890, Thomson married one of his students, Rose Elisabeth Paget. They had a son and a daughter. The son, Sir George Paget Thomson, received the Nobel Prize in Physics in 1937 . Thomson also investigated the nature of positively-charged particles. These experiments led to the development of the mass spectrograph. Thomson was closely aligned with chemists of the time. His atomic theory helped explain atomic bonding and the structure of molecules. Thomson published an important monograph in 1913 urging the use of the mass spectrograph in chemical analysis. Many consider J.J. Thomson's greatest contribution to science to be his role as a teacher. Seven of his research assistants, as well as his own son, went on to win the Nobel Prize in Physics. One of his best-known students was (ERNEST RUTHERFORD), who succeeded Thomson as Cavendish Professor of Physics..

Rutherford's Model(1871-1937). Rutherford model, also called Rutherford atomic model, nuclear atom, or planetary model of the atom, The Rutherford model was devised IN 1911 by the New Zealand-born physicist ERNEST RUTHERFORD to describe an ATOM..

He was also known as father of nuclear physics. This model is based on theory, where fast moving alpha-particles were made to fall on a thin gold foil Observations found on Rutherford's model : Most of the fast moving alpha-particles passed straight through the gold foil. Some of the particles get deflected by small angles. It was also found that one out of every 12000 particles appeared to rebound ..

Conclusions made from Rutherford's model. 1. Atom contains a lot of empty space due to which most of the alpha-particles passed without getting deflected through the gold foil. 2. The positive charge of the atom occupies very little space due to which very few particles were deflected from their path. 3. The positive charges are concentrated in a very small volume within the atom due to which a very small fraction of alpha-particle were deflected by 180°. 4. He also concluded that the radius of the nucleus is about 10 5 times less than the radius of the atom..

The nuclear model of an atom on the basis of Rutherford’s experiment :.

Drawbacks of Rutherford’s model of the atom :. The nuclear model of an atom suggested by Rutherford failed as it couldn’t justify the statement that how an atom remains stable after having positive and negative charge. As per the Maxwell’s theory , if any charged particle would move in a circular orbit it will radiate energy. So, if electron start moving in a circular motion around the nucleus they would also radiate (loss) some energy and as a result they would fall into the nucleus due to presence of high positive charge . This theory proves that if this were so, the atom should be highly unstable and hence, the matter would not exist in the form that we know, as we know matter are quite unstable..

Interesting Facts About Rutherford. HE WAS THE FOURTH OF TWELVE CHILDREN BORN TO JAMES RUTHERFORD AND MARTHA THOMPSON HE EARNED HIS BA, MA AND BSC DEGREES FROM THE CANTERBURY COLLEGE IN CHRISTCHURCH, NZ HE INVENTED A RECEIVER TO DETECT RADIO WAVES HE COLLABORATED WITH J.J. THOMSON TO STUDY THE IONIZATION OF GASES BY X-RAYS.

RUTHERFORD MARRIED MARY GEORGINA NEWTON IN 1900 HE DISCOVERED ATOMS WERE NOT INDESTRUCTIBLE DURING HIS RESEARCH ON RADIOACTIVITY RUTHERFORD WAS THE FIRST PERSON FROM OCEANIA TO WIN A NOBEL PRIZE HE WAS CONFERRED WITH THE TITLE BARON RUTHERFORD OF NELSON IN 1931 RUTHERFORD DIED UNEXPECTEDLY DUE TO COMPLICATIONS OF A STRANGULATED HERNIA.

. ANS. The Protons and the Neutrons are together known as nucleons.

Bohr’s model(1885-1962). In atomic physics, the Bohr model presented by Niels Bohr is a system consisting of a small, dense nucleus surrounded by orbiting electrons -- similar to the structure of the Solar System, but with attraction provided by electrostatic forces in place of gravity.

this model of an atom proposed that :. The electron spin around the nucleus of the atom in a certain special orbit known as discrete orbits of electrons. The electrons do not emit any energy while revolving in these discrete orbit These shells of orbits are known as energy levels which are represented by the letters K,L,M,N,... and the numbers, n = 1,2,3,4 ,....

This can be best understood by following diagram.

Successes & Failures of Bohr Model. + Rydberg Equation predicts many lines of He (except for a few extra lines) Higher resolution diffraction gratings in advanced spectrographs indicated some transitions were multiple (fine structure) Bohr’s “n” quantum number is only partially associated with angular momentum (1s, 2s, 3s,… states do not have angular momentum) Worked best for single-electron atoms H + , He + , Li +.

Interesting Facts About BOHR. Neil's Bohr wasn’t as good a writer as he was a student in his younger years Bohr was reputed to setting off explosions in his University’s lab Bohr won a Nobel prize at the same time as Albert Einstein Bohr’s son Aage also won a Nobel Prize. Bohr never ran out of Carlsberg beer!.

Bohr has an element named after him Bohr aided Jewish scientists in their escape from the Nazis The Copenhagen Institute for theoretical physics was Bohr’s brainchild Bohr used an alias, “Nicholas Baker” Bohr advocated for nuclear science for peace.