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who is Democritus
he is a central figure in the development of the atomic theory of the universe
What is the main idea of John Dalton
All matter is composed of extremely small particles called atoms
what is the discovery of J.J. Thomson
the electron
what is James Chadwick discovered?
he discover the neutron
What was Niels Bohr known for?
He adapted Rutherford's nuclear structure to Max Planck's quantum theory and created the Bohr model, the most widely accepted model of the atom.
What is Ernest Rutherford best known for?
Ernest Rutherford is known for his pioneering studies of radioactivity and the atom.
What did Ernest Rutherford do to discover?
postulated the nuclear structure of the atom, discovered alpha and beta rays, and proposed the laws of radioactive decay.
What was Thomson's conclusions?
the rays were negatively charged and moved around the positive charge.
Why did J.J. Thomson do his experiment?
Thomson wanted to see if, by bending the rays with a magnet, he could separate the charge from the rays.
What was Democritus known for?
a central figure in the development of the atomic theory of the universe.
What is the Dalton's atomic theory?
A theory of chemical combination
What did Dalton discover about the atom?
all matter is made of atoms, which are indivisible.
What is John Dalton best known for?
introducing the atomic theory into chemistry and for his work on human optics.
What was Ernest Rutherford's gold foil experiment?
A piece of gold foil was hit with alpha particles, which have a positive charge. Most alpha particles went right through. This showed that the gold atoms were mostly empty space.
What did Rutherford's foil experiment reveal?
atoms are mostly empty space, with the positive charge concentrated in a nucleus.
What is Niels Bohr atomic theory?
Electrons revolve around the nucleus in stable orbits without emission of radiant energy.
What theory did Bohr discover?
quantum theory
How did Chadwick detect neutrons?
How did Chadwick detect neutrons?
What experiment did Chadwick carry out?
beryllium bombardment
What did Chadwick discover in 1932?
the core also contained a new uncharged particle, which he called the neutron.
How did Democritus theory explain?
atoms were uniform, solid, hard, incompressible, and indestructible and that they moved in infinite numbers through empty space until stopped.
What discovery did Democritus make?
all matter was formed of different types of tiny discrete particles
What was Democritus model called?
atomos
Who discovered atom before Dalton?
The Greek philosopher Democritus
What is Dalton's theory for dummies?
each atom of an element was identical to other atoms of the same element, and they combined together in specific ways to form the more complex substances we see in our universe.