C1 history of the atom Flashcards
Who proposed the first atomic theory?
John Dalton
What is the basic unit of matter?
Atom
True or False: The atom was first described by Democritus.
True
Which scientist discovered the electron?
J.J. Thomson
Fill in the blank: Dalton’s atomic theory included the idea that atoms of the same element are ______.
identical
What model did J.J. Thomson propose for the atom?
Plum pudding model
Who conducted the gold foil experiment?
Ernest Rutherford
What did Rutherford’s gold foil experiment reveal about the atom?
The atom has a small, dense nucleus.
What subatomic particle was discovered by James Chadwick?
Neutron
True or False: The nucleus of an atom is positively charged.
True
Fill in the blank: The electron cloud model replaced the ______ model.
planetary
What did Niels Bohr contribute to atomic theory?
Bohr model of the atom with quantized energy levels.
Which particle has a negative charge?
Electron
What is the charge of a neutron?
Neutral
What are isotopes?
Atoms of the same element with different numbers of neutrons.
Who proposed the idea of quantized energy levels in atoms?
Niels Bohr
True or False: All atoms of a given element have the same mass.
False
What is the term for the center of an atom?
Nucleus
Which model describes electrons in fixed orbits around the nucleus?
Bohr model
Fill in the blank: The modern atomic model is based on ______ mechanics.
quantum
Name the three main subatomic particles.
Protons, neutrons, electrons
What is an atom’s atomic number?
The number of protons in the nucleus.
True or False: Protons have a positive charge.
True
What is the mass of an electron compared to a proton?
Much smaller
What key concept did Dalton introduce about chemical reactions?
Atoms are rearranged but not created or destroyed.
Which physicist is known for the uncertainty principle?
Werner Heisenberg
