Around 430BC Democritus made very significant observation for his lifetime he stated that atoms are the building blocks for all things and that atoms are tiny, indivisible, and differ only by shape and arrangement. He also stated that atoms cannot be destroyed and that atoms correspond to the substance that they make.
Around 300BC, Aristotle didn’t believe that atoms were of different sizes and had regular geometric shapes which contradicted societies belief for his day. He believed all matter contained fire, air, earth, and water and emotions of the world contributed to good and bad.
Jan 3, 1778
In 1778 Lavoisier did many experiments with gases, he basically discovered oxygen and hydrogen and their names stuck. When some substances were burned he stated that their loss in mass was gas molecules escaping into the atmosphere which led him to establish the Law of Conservation of Mass.
JOSEPH LOUIS PROUST
Jan 3, 1799
In 1799 Proust was studying sugar composition in Spain which led him to the Law of Constant Composition (later merged into the Law of Definite Proportions) stating no matter how a compound is produced or how much there is of it the reactants would always combine in the same way.
Jan 3, 1803
In 1803, after many years of researching atoms John Dalton published his Theory on atoms which stated;
• All elements are made up of tiny indivisible particles, known as atoms
• Atoms of the same element are identical with respect to their weights
• Atoms of different elements are different from each other and can be identified by their relative weights
• Atoms can neither be divided into smaller particles nor destroyed
He also expanded upon the idea of definite proportions and the Law of Multiple
Jan 3, 1832
Michael Faraday mostly studied electricity but he also studied gases such as chlorine and he would diffuse them. He also studied elements forming into compounds. In 1832 he studied the effects of electricity on atoms and coined the phrase electrolysis
MARIE AND PIERRE CURIE
Jan 1, 1896
Marie & Pierre Curie discovered two new elements and did vast research on radioactivity in 1896. Which helped shape the understanding of radioactive atoms and their unique properties.
Jan 3, 1896
Henri was experimenting with an ore containing uranium in his lab and found on accident that if he left it on a photographic plate without any light the ore still left an image. That happened because uranium is radioactive and that was the first time it was documented as such.
Jan 3, 1897
In 1897 scientist JJ Thompson created a tube with a positively charged anode side and a negatively charged cathode side which made sort of a beam then he placed a magnet in the middle and the beam bended toward the positive end of the magnet meaning the particles in the beam were negatively charged thus electrons.
Jan 3, 1900
In Dec. of 1900 Planck discovered that electromagnetic energy is released in quantized specific amounts. In the formula to find the amount of energy that is released when electrons jump energy levels, h is plancks constant