Ancient Thinkers
He stated that matter has four properties: hot, cold, dry, and wet.
Who is Aristotle?
He published his atomic theory in 1803, stating that atoms are "uncuttable".
Who is John Dalton?
In 1913, he proposed that electrons travel around the nucleus in specific paths called energy levels.
Who is Niels Bohr?
J.J. Thomson used this specific laboratory equipment to discover electrons.
What is a Cathode-Ray Tube?
The timeline year associated with the discovery of the "plum pudding" model.
What is 1897?
This Greek philosopher stated that atoms are made of a single material formed into different shapes and sizes.
Who is Democritus?
This 1897 model depicted negative particles trapped within a positively charged substance.
What is the "plum pudding" model?
Modern scientists state electrons are found in these regions, rather than fixed paths.
What are electron clouds?
Ernest Rutherford used this famous experiment to prove atoms are mostly empty space.
What is the Gold-Foil Experiment?
Rutherford concluded that an atom is not solid, but contains mostly this.
What is empty space?
The Greek word meaning "not to be cut" refers to the smallest piece of matter.
What is "Atomos"?
Dalton stated that atoms of different elements are this.
What is different?
Rutherford discovered that an atom's mass is mostly concentrated here.
What is the nucleus?
This subatomic particle was discovered during Rutherford's gold-foil research era.
What is the proton?
In Bohr's model, energy levels are located at certain distances away from this central structure.
What is the nucleus?
The four basic elements that Aristotle claimed all matter was made of.
What are fire, air, water, and earth?
Thomson discovered these small, negatively charged particles inside the atom.
What are electrons?
In the modern cloud model, an electron's precise location depends entirely on this factor.
What is how much energy it has?
The scientist who expanded the 20th-century model by discovering the neutron.
Who is James Chadwick?
In the modern model, electrons move around the nucleus this many times in just one second.
What is billions of times?
The approximate era or year range associated with Aristotle's widely accepted view of matter.
What is 300 BC to the early 1800s?
According to Dalton's 1803 theory, atoms of the exact same element share this characteristic.
What is being exactly alike?
Three of the 20th-century scientists credited with developing the modern electron cloud model.
Who are Schrödinger, Heisenberg, and Einstein?
Rutherford proved the central nucleus has this specific type of electrical charge.
What is a positive charge?
Chronologically, the order of the first four atomic theorists listed on the timeline, from earliest to latest.
Who are Democritus, Aristotle, Dalton, and Thomson?