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In 1909 Rutherford bombarded a very thin sheet of gold foil with alpha particles, most of which passed straight through undetected - Leaving Cert Chemistry - Question a - 2012
Question a
In 1909 Rutherford bombarded a very thin sheet of gold foil with alpha particles, most of which passed straight through undetected. Some alpha particles, however, we... show full transcript
Worked Solution & Example Answer:In 1909 Rutherford bombarded a very thin sheet of gold foil with alpha particles, most of which passed straight through undetected - Leaving Cert Chemistry - Question a - 2012
Step 1
Step 2
Describe the structure of Thomson's 'plum pudding' model of the atom.
Answer
Thomson's 'plum pudding' model proposes that the atom is a sphere or ball with a positive charge spread throughout its volume. Within this sphere, electrons are embedded like 'plums' in a 'pudding', with the electrons having a negative charge.
Step 3
Explain why some alpha particles were deflected at large angles as they passed through the gold foil.
Answer
Some alpha particles were repelled when they passed near the nucleus due to the positive charge of the nucleus, which repels the positively charged alpha particles. The closer they got to the nucleus, the greater the force of repulsion, causing large angle deflections.
Step 4
Why did this happen to only a very small number of alpha particles?
Answer
This occurred to only a very small number of alpha particles because most of the atom is mostly empty space, and only a small fraction of the particles were in close proximity to the dense, positively charged nucleus during their passage through the foil.
Step 5
Draw a labelled diagram to show the new structure of the atom proposed by Rutherford.
Answer
A labelled diagram should depict the atom with a central nucleus (marked with a '+' for positive charge) surrounded by electrons (shown as 'shells' or 'electron cloud'). The nucleus should be indicated to be very small relative to the overall size of the atom.