In the early 1800s, the English Chemist
John Dalton
Is Aristotle responsible for the 2000 year death of Chemistry?
In ancient Greece, the popular philosopher Aristotle declared that all matter was made of only four elements: fire, air, water and earth. He also believed that matter had just four properties: hot, cold, dry and wet.
Death
to the field of Chemistry for 2000 years!
What was John Dalton's atomic theory?
A theory of chemical combination, first stated by John Dalton in 1803. It involves the following postulates: (1)
Elements consist of indivisible small particles (atoms)
. (2) All atoms of the same element are identical; different elements have different types of atom. (3) Atoms can neither be created nor destroyed.
What happened in Rutherford gold foil experiment?
The gold-foil experiment showed that
the atom consists of a small, massive, positively charged nucleus with the negatively charged electrons being at a great distance from the centre
. Niels Bohr built upon Rutherford's model to make his own.
Who are the main scientists involved in atomic theory?
- Democritus.
- John Dalton.
- Michael Faraday.
- J. J. Thomson.
- Robert Millikan.
- Ernest Rutherford.
Are atoms mostly made of empty space?
Atoms are not mostly empty space because there is no such thing as purely empty space
. … Atoms are filled with electrons. It's true that a large percentage of the atom's mass is concentrated in its tiny nucleus, but that does not imply that the rest of the atom is empty.
Who said atoms contain mostly empty space?
In 1911, a British scientist named
Ernest Rutherford
discovered that an atom is mostly empty space. He concluded that the positively charged particles are contained in a small central core called the nucleus.
What was Dalton wrong about?
Drawbacks of Dalton's Atomic Theory
The indivisibility of an atom
was proved wrong: an atom can be further subdivided into protons, neutrons and electrons. … According to Dalton, the atoms of same element are similar in all respects. However, atoms of some elements vary in their masses and densities.
What parts of Dalton's atomic theory are still true?
Although two centuries old, Dalton's atomic theory remains valid in modern chemical thought. 1)
All matter is made of atoms
. Atoms are indivisible and indestructible. 3) Compounds are formed by a combination of two or more different kinds of atoms.
Why is Dalton credited?
Why is Dalton credited with
proposing the first atomic theory
if Democritus was talking about atoms almost 2,200 years earlier? – Dalton's theory was the first scientific theory because it relied on scientific investigative processes. … – Dalton used creativity to modify Proust's experiment and interpret the results.
Why did the gold foil have to be thin?
Gold was used because it
was the only metal that could be rolled out to be very
, very thin without cracking. Since the gold foil was very thin, it was thought that the alpha particles could pass straight through it, or possibly puncture the foil. … most of the alpha particles did pass straight through the foil.
What was Rutherford's experiment called?
Rutherford's experiment is called
the gold foil experiment
because he used gold foil.
What are the conclusion of gold foil experiment?
The gold foil experiment led to the conclusion that
each atom in the foil was composed mostly of empty space because
most alpha particles directed at the foil 1) An atom is mostly empty space with a dense, positively charged nucleus.
Who invented electron?
Joseph John “J. J.” Thomson
. In 1897 Thomson discovered the electron and then went on to propose a model for the structure of the atom. His work also led to the invention of the mass spectrograph. The British physicist Joseph John (J. J.)
Who proved Dalton's theory wrong?
Atomic Theory. In 1897,
English physicist J. J. Thomson
(1856–1940) disproved Dalton's idea that atoms are indivisible. When elements were excited by an electrical current, atoms break down into two parts.
What did the alpha scattering experiment reveal?
Rutherford's alpha scattering experiment showed that
the majority of alpha particles fired at a thin sheet of gold leaf passed straight through
. Some of the particles passed through the leaf with a small angle of deflection and very few were deflected at very large angles.
