A theory of the structure and behaviour of atoms has taken more than two millennia to evolve, from the abstract musings of ancient Greek philosophers to the high-tech experiments of modern scientists.

At the very end of the 19th century that technology became advanced enough to allow scientists a glimpse of the atom’s constituent part: the electron, nucleus, proton, and neutron.

Ideas of the Ancient Greeks on the Atom

The development of the atomic model of matter started from the early Greek concept on the atom. Greek philosophers and thinkers were the first to describe matter and to wonder whether matter could be divided infinitely into smaller pieces or if there was a limit to the number of time that a piece of matter could be divided.

The idea that all matter is made up of tiny, indivisible particles, or atoms, is believed to have originated with the Greek philosopher Leucippus of Miletus and his student Democritus of Abdera in the 5th century B.C. (The word atom comes from the Greek word atomos, which means “indivisible.”)

Democritus’ Atomic Theory

1.All matter consists of invisible particles called atoms.

2.Atoms are indestructible.3.Atoms are solid but

invisible4.Atoms are homogenous.

5. Atoms differ in size, shape, mass, position, and arrangement.

Solids are made of small, pointy atoms.

Liquids are made of large, round atoms.

Oils are made of very fine, small atoms that can easily slip past each other.

Democritus’ atomic model was

simply a round sphere with no

electrons, protons, or neutrons.

Contributions of Alchemists to the

Science of Chemistry

Chemists use symbols to designate the elements. Some of the symbols

for some elements used by alchemists are given in figures

below.

Gold Silver Copper

Iron

Mercury

LeadTin

A pseudoscience, called alchemy, dominated 2000 years of chemistry history. Some alchemists are mystics and some were serious scientists. The serious ones discovered several elements and prepared mineral acids. The development of systematic metallurgy (with the extraction of metals from ore) and the medicinal application of metals from ore laid the foundations of modern chemistry.

A truly quantitative experiment was performed by Robert Boyle, who carefully measured the relationship between the pressure and volume of air. Boyle insisted the alchemists’ view that metals were not true elements and time would come that a way to change one metal into another would eventually be found.

Thank You!Prepared by:Mhyla AliñoGrade 11 - Aguinaldo