History of Atomic structure Flashcards
How long did it take for the ancient idea of the atom to become a theory?
More than 2,000 years.
What did scientists rely on to develop atomic theories?
Early ideas as a guide and reference.
Who proposed the first modern atomic theory?
John Dalton.
How did John Dalton describe the atom?
As a solid, indestructible sphere, like a billiard ball.
What was JJ Thomson’s major discovery?
The electron.
What experiment led JJ Thomson to discover the electron?
The cathode ray tube experiment.
What was Ernest Rutherford’s major contribution to atomic theory?
The discovery of the nucleus.
What is Rutherford’s atomic model called?
The Nuclear Model of the Atom.
What did Niels Bohr contribute to atomic theory?
He adapted Planck’s theory to Rutherford’s model, introducing electron orbits.
What refinements did Arnold Sommerfeld introduce to Bohr’s model?
- Elliptical orbits.
- Allowance for orbiting motion of electrons.
- Consideration of relativistic mass effects.
What are the three subatomic particles?
Proton, neutron, electron.
What is the charge and location of a proton?
Positive (+1), found in the nucleus.
What is the charge and location of a neutron?
No charge, found in the nucleus.
What is the charge and location of an electron?
Negative (-1), found outside the nucleus.
What determines an element’s identity?
The number of protons (atomic number).
What happens if electrons are added or removed from an atom?
It becomes an ion.
What is a cation?
A positively charged ion (electron removed).
What is an anion?
A negatively charged ion (electron added).
What is the mass number of an atom?
The sum of protons and neutrons.
What are isotopes?
Atoms of the same element with different mass numbers.
How do you calculate the number of neutrons in an atom?
Neutrons = Mass number - Atomic number.
