Dylan+S.

John Dalton(1766-1844) John Dalton was a English Chemist, physicist, and a meteorologist. He is most known for his study in atomic theory.
 * History of the Atom**


 * 1704 || Isaac Newton || Proposed a mechanical universe with small solid masses in motion. ||
 * 1803 || John Dalton || Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass. ||
 * 1832 || Michael Faraday || Studied the effect of electricity on solutions, coined term "electrolysis" as a splitting of molecules with electricity, developed laws of electrolysis. Faraday himself was not a proponent of atomism. ||
 * 1859 || J. Plucker || Built one of the first gas discharge tubes ("cathode ray tube"). ||
 * 1869 || Dmitri Mendeleeff || Arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of the their atomic weights". This became known as the Periodic Law. ||
 * 1873 || James Clerk Maxwell || Proposed electric and magnetic fields filled the void. ||
 * 1874 || G.J. Stoney || Proposed that electricity was made of discrete negative particles he called "electrons". (Link to info on electrons) ||
 * 1879 || Sir William Crookes || Discovered cathode rays had the following properties: travel in straight lines from the cathode; cause glass to fluoresce; impart a negative charge to objects they strike; are deflected by electric fields and magnets to suggest a negative charge; cause pinwheels in their path to spin indicating they have mass. ||
 * 1886 || E. Goldstein || Used a CRT to study "canal rays" which had electrical and magnetic properties opposite of an electron. ||
 * 1895 || Wilhelm Roentgen || Using a CRT he observed that nearby chemicals glowed. Further experiments found very penetrating rays coming from the CRT that were not deflected by a magnetic field. He named them "X-rays". ||
 * 1896 || Henri Becquerel || While studying the effect of x-rays on photographic film, he discovered some chemicals spontaneously decompose and give off very pentrating rays. ||
 * 1897 || J.J. Thomson || Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 108 coulombs/gram. ||
 * 1897 || J.J. Thomson || Studied "canal rays" and found they were associated with the proton H+ . ||

Protons, Neutrons and Electrons. Proton=positive charge Neutron=neutral charge Electron= negative charge
 * Atomic Structure**

What is an atom? Atoms are the building blocks of matter. The word ‘atom’ was originally meant to indicate the smallest indivisible part of matter. However, research revealed that an atom was in fact not the indivisible unit of matter and that it consisted of other particles. They came to be known as the subatomic particles. What makes up an atom? What are the different parts of an atom? Let us find out.

The central portion of an atom is known as the atomic nucleus. It consists of protons, which carry positive charge and neutrons, which carry no electric charge. The negatively charged electrons orbit the atomic nucleus. The protons and neutrons in an atomic nucleus contribute to the atomic mass. However, the electrons floating in the region around the nucleus are extremely lightweight subatomic particles.

If protons are positively charged particles and electrons are negatively charged, how does an atom not have electric charge? Do the neutrons neutralize the electric charge of an atom? Imagine, if atoms were to bear electric charge, we would be getting electrical shocks on touching anything around us. As atoms make up matter and matter makes up the universe, we would probably have to thrive in an electrically charged world! But thanks to the equal number of protons and electrons in an atom, matter does not possess electric charge. Yes, every atom has an equal number of protons and electrons. This nullifies the electric charge, thus making atoms electrically neutral.

Atoms get together to form molecules. When atoms of different elements come together, compound molecules are formed. As you might know, there are two types of compounds, ionic and covalent. The ions of ionic compounds are bound together due to the electrostatic forces between oppositely charged bodies. When atoms share pairs of electrons to form chemical bonds, they are known as covalent compounds. Chemical reactions between atoms of different elements result in the formation of complexly structured compounds. Being the fundamental units of matter, it won’t be an exaggeration to say that atoms are omnipresent; they are within you, around you and everywhere.