All matter is made up of very small particles called atoms. They are small, indivisible particles that cannot be seen by the naked eye. With the advancement of technology, atoms can now be viewed through scanning microscopes (Genesis, n.d.). Protons, electrons and neutrons are the particles that can be found in an atom. Protons are positively charged particles, while the electron is negatively charged. Neutrons are uncharged particles (Genesis, n.d.). The mass of the atom is measured from the mass of the proton and neutron, and they are located at the center of the atom clumping together and called the nucleus. Protons weigh approximately 1.67 x 10-24 grams or 1 atomic mass unit (amu) and the neutron also weighs 1 atomic mass unit (Interactives, n.d.). As mentioned earlier, all elements are made up of atoms. The similarity of the elements and their differences are also characterized by the properties of the atoms.
Dmitri Mendeleev was the scientist who created the periodic table of elements. In 1868, he arranged the different known elements during his time in order of their mass. That time, there were only sixty elements, so it was not so difficult. He observed that there was a pattern of similarity in characteristics on the arranged elements. This pattern was referred to as periodicity.
In 1913, a scientist named Henry Moseley rearranged Mendeleev’s table in order of the atomic number. ...Show more