• Period: 700 BCE to 300 BCE


    -Tales of Miletus
    -Heraclitus of Ephesus
    -Xenophanes of Colophon
    -Empedocles of Akragas
    -Leucippus of Miletus
    -Democritus of Abdera
  • 624 BCE

    -Tales of Miletus

    -Tales of Miletus
    Years they lived: 624 a. C.-ibid., c. 546 a. C
    Thales's theory about the cause of earthquakes is consistent with his hypothesis that earth floats upon water. It seems that he applied his floating on water simile to the natural phenomena of earthquakes. Aëtius recorded that Thales and Democritus found in water the cause of earthquakes
  • 585 BCE


    Years they lived: 585 a.C.- 528-525 a.C.
    Anaximenes elaborates an interesting theory about the nature of the world and the formation of bodies where rarefaction and condensation is the way in which the universe has developed: «the soul is air; the fire, rarefied air; when the air condenses it becomes, first, water; later, if it becomes denser, on earth and, finally, on stone. » Anaximenes believed that the Earth was flat "like a leaf"
  • 570 BCE

    -Xenophanes of Colophon

    -Xenophanes of Colophon
    Years they lived: 570 a. C. - 475 a. C.
    He is considered the first theologian in the history of culture, the first to deal with the problem of God. He criticized the anthropomorphism of the Homeric gods as well as their immorality and postulated the existence of a unique God.
  • 540 BCE

    -Heraclitus of Ephesus

    -Heraclitus of Ephesus
    Years they lived: 540 a. C.-ibidem, 480 a. C.
    The Greek thinker believed that the world experiences a process of continuous birth and destruction to which nothing escapes. Within the incessant change of things, Heraclitus postulates that there is an eternal unity or principle embodied by fire.
  • Period: 500 BCE to

    History of atom

  • 484 BCE

    -Empedocles of Akragas

    -Empedocles of Akragas
    Years they lived: 484/3 a. C.- 424/3 a. C.
    In his philosophical poem De la Naturaleza, he reduces all the diversity of things to four "roots": earth, water, air and fire. This theory of the four elements (or "principles" of nature was maintained in ancient and medieval philosophy for many centuries. Empedocles explained the union and separation of the elements by the action of two opposing forces: friendship and enmity
  • 460 BCE

    -Leucippus of Miletus

    -Leucippus of Miletus
    Years they lived: 460 – 370 a.C.
    He believed that according to the mechanistic
    atomism of Leucippus, reality is made up of both atoms and emptiness. Atoms (ἄτομοι, which cannot be divided) are infinite particles, indivisible, of varied shapes and always in motion.
  • 460 BCE

    -Democritus of Abdera

    -Democritus of Abdera
    Years they lived:  460 - 370 a.C.
    Democritus thought and postulated that atoms are
    indivisible, and are distinguished by shape, size, order, and position. It is believed that the distinction by weight was introduced by Epicurus years later or that Democritus mentioned this quality without developing it too much.
  • 401 BCE

    ARISTOTLE (Atom)

    ARISTOTLE (Atom)
    The matter was continuous, could be divided infinitely in smaller and smaller particles.
  • 384 BCE


    Years they lived: 384 a. C.-Calcis, 322 a. C.
    Aristotle admits that reality is changing, true knowledge is knowing how to identify the substance of each thing, the work of the understanding. This process consists of recognizing causes and principles, among which is the formal cause, the essence.
  • 200 BCE


    Alchemy began to develop around the 3rd century BC. in the Alexandria region and became almost completely extinct in the 16th century. Its existence was given by the mixture of three currents: Greek philosophy, Eastern mysticism and Egyptian technology.
    The result of the practice of alchemy was the creation of multiple substances, techniques, and processes and tools that are now fundamental to the practice of various sciences.
  • Period: 200 BCE to

    Alchemy and Iatrochemistry

    -Philippus Theophrastus Bombastus von Hohenheim
  • 426

    -Zosimos de Panopolis

    -Zosimos de Panopolis
    He is the author of the oldest known books that deal with the practice of alchemy. In it he explains that alchemy has its origin in Egypt, practiced only within the priestly class. However, his claims have no basis to prove it. Also, in his books some of the techniques used by the first alchemists are explained.
    Some authors locate the origin of alchemy in the lessons taught by the Neo-Platonians. This practice prevailed until the 5th century.
  • 501

    Leucippus and Democritus(Atom)

    Leucippus and Democritus(Atom)
    The subdivision of matter produce the atoms out meaning "uncut,
    Greek theories were based on abstract thinking,
    not in experimentation. The existence of the atom
    remained not demonstrated until 1904.
  • 1493


    Philippus Theophrastus Bombastus von Hohenheim, known as Paracelsus was the main defender of atrochemistry
    Paracelsus was a doctor who was born near Zurich, Switzerland, in 1493. In addition to being a doctor, he was an astrologer and alchemist and his main contribution to medicine was the creation of the first drugs based on chemicals and minerals. ... He thought that only doctors with this innate talent should practice medicine.
  • 1501


    It was an medical trend between the 16th and 17th centuries.(1501-1600)
    Iatrochemistry is a historical branch of science that linked chemistry and medicine and can be considered as the forerunner of modern pharmacology and biochemistry.
    Iatrochemistry suggest that poisons, or diseases, could also be cured by poisons; thus, poisons could have beneficial medical effects.Iatrochemistry claimed to many chemically prepared medicines in this period which contained toxic components.
  • -Robert Boyle

    -Robert Boyle
    January 25, 1627-December 31, 1691
    Was the first to demostrate Galileo's claim that, in a vacuum, a feather and a piece of lead fall at the same speed, and he also established that sound is not transmitted in a vacuum.He also created Boyle's Law. Boyle's Law states that the pressure of a gas in a closed container is inversely proportional to the volume of the container, when the temperature is constant. Volume is inversely proportional to pressure: If pressure increases, volume decreases.
  • -Robert Hooke

    -Robert Hooke
    July 18, 1635-‎March 3, 1703
    Robert Hooke: Hooke discovered the cells by looking at a cork slide under the microscope (which he himself created). He realized that it was made up of small polyhedral cavities that resembled the cells of a honeycomb.
    Hooke's Law: Establishes that the unit elongation experienced by an elastic body is directly proportional to the force applied on it.
    This means that if you increase the force applied on an elastic body, the elongation will increase too.
  • -Dalton

    He was the first to formulate a scientifically based atomic
    model. He proposed an ATOMIC THEORY , showing that it is
    possible to determine the relative masses of the atoms of
    different elements. According to Dalton, each element was composed of atoms.
    1. Each element is composed of extremely small particles
    called atoms.
    2. All atoms of an element are identical.
    3. Atoms of elements not become different atoms in
    chemical reactions.

    In the model proposed by Thomson (Plum-pudding
    model) the atom is composed of negatively charged
    electrons in an atom positively charged, like raisins in
    a pudding. Thomson discovers the existence of the
    electron through the experiment CRT. (cathode ray
    Cathode rays are deflected by electric and magnetic
    fields and negatively charged the metal, the rays are
    negatively charged particles and mass. Discovery of the

    He studied radioactive releases discovered by HENRY
    Classified these in alpha rays (composed by two protons
    and two neutrons which travel to 0.05 times the speed of
    light particles), beta (electron beam moving at 0.4 times
    the speed of light) and gamma (a form highly energetic
    light, have no charge and are similar to X-rays).
    Using alpha particles, performed “the experiment of gold
    The Atom has a positive core surrounded by negative electrons.

    The Danish physicist Niels Bohr proposed a new atomic model based on three
    1.- Electrons orbit the nucleus in stationary orbits without
    emitting energy.
    2.- Electrons can jump from one electronic level to another
    without passing through intermediate states.
    3.- The jump of an electron from one quantum level to
    another involves the emission or absorption of a single
    quantum of light (photon) whose energy corresponds to
    the energy difference between the two orbits.

    The current atomic model was developed during the 1920s, by Schrödinger, Heisenberg, among other researchers. . It is a model of great mathematical complexity, to the point that when using it, only the hydrogen atom can be solved with precision.
    In any case, the quantum-mechanical atomic model fits very well with the experimental observations.
    An orbit is a region of space in which the probability of finding the electron is greatest.

    In 1932, Chadwick made a fundamental discovery in
    the field of nuclear science: discovered the particle in
    the nucleus of the atom that would happen to be
    called neutron, prediction done some years before.
    This particle has no electric charge.
    It is capable of penetrating and dividing the core of
    the heaviest elements. From this way, Chadwick
    raided the road to uranium 235 fission and to the
    creation of the atomic bomb.