The History Of The Atom

Timeline created by milnen
  • 200

    Kanada (200BC)

    • Kanada was one of the first philosophers to realise that the atom is an indestructible particle of matter.
    • He became aware of this while eating food. He was throwing away little parts of it but realised that they did not break away further and they couldn’t break away further.
    Like Democritus, Kanada thought that atoms make up the essential elements. Fire, earth, air and water.• He called the indivisible matter anu, which is know known as an atom.
  • 384

    Aristotle (384BC)

    • Aristotle saw that all objects have matter and a form.
    • He noted that some of these particles can change and adapt like marble when it gets carved by the sculptor.
    • Although he knew everything had matter he disagreed with Democritus and did not believe that the atom exists which is why he has no atomic model.
  • 460

    Democritus (460BC)

    • Democritus and his partner Leucippus were probably the first philosophers to delve deep into the theory of the atom.• They realised that everything around us is made up of atoms and they come in different sizes, weights and shapes.
    • He realised that there are an infinite amount of atoms in our world and that they are completely indestructible.• He was the first person to use the term atom.
    Democritus thought the atoms was like a ball which was either slippery or rough.
  • 492

    Empedocles (492BC)

    • As Thales did, Empedocles tried to prove that matter is real and that it is made up of different particles and substances.• He tried to prove that different forms of matter attract and separate depending on their environment and their positioning. He didn’t get the statistics and the number of particles right to get the end result right though.
  • Jan 1, 624

    Thales (624BC)

    • Thales was one of the first people to ever discover matter and atoms. He delved deep into the theory of matter.
    • Thales made many assumptions during his career and he based them on reality, not mythology.
    • Even though many of his ideas were far-fetched and incorrect. He was very good at what he did with the little knowledge he had to work with.
  • Antoine Lavoisier

    • Antoine was studying the types of atoms and he was trying to put them into a order or groups. He discovered that some forms of atoms can be linked together to create another form of matter.• He tested if hydrogen and oxygen when put together makes water.
  • John Dalton

    • John Dalton’s biggest achievement was when he started to measure the weights of elements and started to put the weights and elements in order.• He figured out that hydrogen is the only element that weighs 1.• Dalton started using names like CO2 or O2 • He started using single to multiple proportion. This studies the way the atom is made up.• He noticed that an atom cannot be created or destroyed.
    He showed the atom as a billiard ball which is hard to destroy and cannot be multiplied.
  • Henri Becquerel

    • Antoine Henri Bequerel was one of the first scientists to study the links of radioactivity to an atom.• Bequerel realised that radioactivity is created inside the nucleus of an atom. He found out that protons and neutrons are inside an atom and they come in different numbers but there needs to be the correct number of protons and neutrons for the atom to be stable.
  • Sir Joseph John Thomson

    • Thomson was one of the first scientist to really believe that there is more in an atom than protons and neutrons. This led to the discovery of the electron.• He also noted that an atom is divisible and in 1906 he was the first to prove that hydrogen has only one electron per atom.• Plum pudding model. The fruit of the pudding is the negative and the cake is the positive. This theory was eventually flawed by Rutherford when he realised that the atom is mostly empty.
  • Max Planck

    • Max Planck was a well respected professor and scientist in his field.• He worked on coming to a conclusion of radiation. He tried to work out the link between heat, atoms and radiation.He formulated the quantum theory.
  • Ernest Rutherford

    • Ernest worked on the idea that an atom has a positive nucleus, which is orbited by negative electrons.• He noted that the mass of an atom is the nucleus and the rest is empty space. He worked this out while he was experimenting with radioactive particles and gold. He expected the particles to bounce back off the gold but most of them went through the gold. Rutherford flawed the plum pudding model by realising that all the weight is in the nucleus using this experiment.
  • Niels Henrik David Bohr

    • Neils Bohr extended on Rutherford’s theory. • He stated that electrons are in a clear orbit, they can move between the orbits but don’t move in or out.• He also realised that an electron has to emit a certain amount of energy in its orbit in order to keep the atom stable.
  • Erwin Rudolf Josef Alexander Schrodinger

    • Erwin used the bohr model to expand our knowledge of the placing of the electrons and the way they are orbiting around the atom.
    • Erwin used mathematics to estimate where the electron is likely to be.
  • Henry Moseley

    • Moseley studied under Rutherford when he developed a x-ray which allowed people to study an atoms structure.• This discovery allowed them to more accurately position elements on the periodic table. Shortly after he was killed in Gallipoli.
  • Sir James Chadwick

    • James Chadwick was awarded the Nobel laureate for his discovery of the neutron.• Although the existence of the neuron was known on one knew what exactly was inside or what it was made up of. James realised that the neuron does not have a large electric charge.