Histroy Of The Atom Flashcards
What are atoms?
Atoms are the tiny particles of matter that make up everything in the universe.
Who first described atoms as solid spheres?
John Dalton described atoms as solid spheres at the start of the 19th century.
What did J.J. Thomson discover about atoms in 1897?
J.J. Thomson concluded that atoms contain smaller, negatively charged particles called electrons.
What is the ‘plum pudding model’?
The ‘plum pudding model’ is a theory that proposed atoms are made of a positively charged ‘pudding’ with negatively charged electrons embedded within.
Who conducted the gold foil experiment?
Ernest Rutherford, along with Hans Geiger and Ernest Marsden, conducted the gold foil experiment in 1909.
What was expected from the gold foil experiment based on the plum pudding model?
It was expected that positively charged alpha particles would pass straight through the gold foil.
What were the actual results of the gold foil experiment?
Some alpha particles were deflected more than expected, indicating that the plum pudding model was incorrect.
What theory did Rutherford propose after the gold foil experiment?
Rutherford proposed the theory of the nuclear atom, which includes a tiny, positively charged nucleus surrounded by a ‘cloud’ of electrons.
What was Niels Bohr’s contribution to atomic theory?
Niels Bohr proposed that electrons exist in fixed orbits, or shells, around the nucleus.
Fill in the blank: Bohr suggested that electrons can only exist in _______.
[fixed orbits or shells]
What does the current model of the atom emphasize?
The current model emphasizes a nucleus at the center with electrons in defined shells.
How does scientific knowledge develop according to the text?
Scientific knowledge develops through evidence prompting new ideas and theories that are peer-reviewed.
True or False: Scientific theories are accepted without the need for evidence.
False
What is the significance of peer review in scientific research?
Peer review allows others to check for errors and helps develop new ideas based on existing research.
