Untitled Essay Research Paper Yazan Fahmawi

Untitled Essay, Research Paper

Yazan Fahmawi

T3 IBS Chemistry

Ms. Redman

Historical Development of

Atomic Structure

The idea behind the "atom" goes back to the Ancient Greek society, where

scientists

believed that all matter was made of smaller, more fundamental particles called elements.

They called these particles atoms, meaning "not divisible." Then came the

chemists and

physicists of the 16th and 17th centuries who discovered various formulae of various salts

and water, hence discovering the idea of a molecule.Then, in 1766 was born a man named John Dalton born in England. He is known as the father

of atomic theory because he is the one who made it quantitative, meaning he discovered

many masses of various elements and, in relation, discovered the different proportions

which molecules are formed in (i.e. for every water molecule, one atom of oxygen and two

molecules of hydrogen are needed). He also discovered the noble, or inert gases, and their

failure to react with other substances. In 1869 a Russian chemist, best known for his

development of the periodic law of the properties of the chemical elements (which states

that elements show a regular pattern ("periodicity") when they are arranged

according to

their atomic masses), published his first attempt to classify the known elements. His name

was Mendeleyev, and he was a renowned teacher. Because no good textbook in chemistry was

available at the time, he wrote the two-volume Principles of Chemistry (1868-1870), which

later became a classic. During the writing of this book, Mendeleyev tried to classify the

elements according to their chemical properties. In 1871 he published an improved version

of the periodic table, in which he left gaps for elements that were not yet known. His

chart and theories gained acceptance by the scientific world when three elements he

"predicted"—gallium, germanium, and scandium—were subsequently

discovered In 1856 another

important figure in atomic theory was born: Sir Joseph John Thomson. In 1906, after

teaching at the University of Cambridge and Trinity University in England, he won the

Nobel Prize in physics for his work on the conduction of electricity through gases. He

discovered what an electron is using cathode rays. An electron is the smallest particle in

an atom, whose mass is negligible compared to the rest of the atom, and whose charge is

negative. Though scientists did not know it at the time, electrons were located in an

electron cloud rotating around the nucleus, or center of the atom.Another prominent figure in nuclear physics is a man called Ernest Rutherford, born in

1871. He also was a professor at the University of Cambridge, the University of Manchester

(both of which are in England), and at McGill College in Montreal, Canada. His importance

comes after the discovery of radioactivity in 1896 by a French scientist named Becquerel.

Rutherford identified the three main components of radioactivity: alpha, beta, and gamma

particles. He also found the alpha particle to be a positively charged helium atom. Also,

Rutherford was the first one to discover the true structure of an atom, it having a

central, heavy nucleus with an electron cloud surrounding it. It was Rutherford that,

through experiments such as passing alpha particles through a thin gold foil and watching

some repel, discovered the second constituent of the atom (also the first component of the

nucleus): the proton. The proton has a relative atomic mass of one and has a positive

charge. Rutherford also went down in history as the first man to artificially cause a

nuclear reaction when, in 1919, he bombarded nitrogen gas with radioactive alpha

particles, which resulted in atoms of an oxygen isotope and protons. A unit of

radioactivity, the rutherford, was named in his honor. A colleague of Rutherford’s at

Cambridge University was a man named James Chadwick discovered the third fundamental

particle that makes up the atom: the neutron. This discovery led immediately to the

discovery of nuclear fission and the atom bomb The neutron has a relative atomic mass of

one, and has no positive or negative charge (i.e. it is neutral). It is found in the

nucleus of atoms, along with the proton.

Chadwick was one of the first British

scientists to stress the development of a possible atom bomb. His name was strongly

associated with the British atomic bomb effort, especially during World War II. During the

last two years of W.W.II (1943-1945) Chadwick moved to New Mexico, where he spent much of

his time researching at the Los Alamos Scientific Laboratory, a site chosen by the US

government for nuclear weapon research. The first atomic bomb was developed here with the

help of James Chadwick. Chadwick earned the Nobel Prize for physics in 1935. In the same

era of the development of the atom lived a

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