Early Experiments in Atomic Structure

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Questions and Answers

What type of particles did he suggest must be present in the nuclei of elements other than hydrogen?

Electrons

Electrically neutral particles (correct)

Protons

Atoms

What is the approximate mass of the particles he referred to, in relation to protons?

Much less than protons

Equal to electrons

Approximately the same as protons (correct)

Greater than protons

Which element's nucleus was not mentioned as needing these electrically neutral particles?

Nitrogen

Carbon

Hydrogen (correct)

Oxygen

In the context provided, the term 'nuclei' refers to the cores of which of the following?

Atoms Signup and view all the answers

Which feature distinguishes the particles he proposed for nuclei of larger elements?

They do not carry any electrical charge Signup and view all the answers

What is the purpose of using significant figures in scientific measurements?

To ensure that measurements are as accurate as possible Signup and view all the answers

Which of the following numbers has three significant figures?

56.50 Signup and view all the answers

When adding the numbers 12.1 and 3.45, how many significant figures should the result retain?

3 significant figures Signup and view all the answers

Which of the following correctly represents a round-off error when dealing with significant figures?

Rounding 34.567 to 34.5 when keeping two decimal places Signup and view all the answers

In a measurement of 5000 meters, which digit is considered significant?

The digit 5 Signup and view all the answers

What method did Robert Millikan use to measure the charge of a single electron?

Observing the behavior of charged oil droplets Signup and view all the answers

In what year was Robert Millikan born?

1868 Signup and view all the answers

When multiplying two measurements, how many significant figures should the result have?

The same as the measurement with the fewest significant figures Signup and view all the answers

Which significant scientific contribution is Robert Millikan known for?

Calculation of the charge of an electron Signup and view all the answers

If a measurement has 3 significant figures and another has 5 significant figures, how should the result of their division be reported?

With 3 significant figures Signup and view all the answers

What was one of the key experimental tools used by Millikan in his experiments?

Electrically charged oil droplets Signup and view all the answers

What is the rule for determining significant figures in multiplication and division operations?

The result takes the least number of significant figures from the measurements Signup and view all the answers

What is the time frame of Robert Millikan's life?

1868–1953 Signup and view all the answers

If one number has 2 significant figures and another has 4 significant figures, how many figures should the final answer have after multiplication?

2 significant figures Signup and view all the answers

Which of the following scenarios is correct regarding significant figures in division?

The result should have the same number of significant figures as the measurement with the least count Signup and view all the answers

Why is ice melting classified as a physical change?

It can be reversed. Signup and view all the answers

What characteristic makes cooking a steak a chemical change?

It results in a new substance that cannot be reversed. Signup and view all the answers

Which of the following statements is true regarding physical and chemical changes?

Both involve changes in state. Signup and view all the answers

How is the reversibility of a change significant in classifying it as physical or chemical?

Physical changes can always be reversed. Signup and view all the answers

What does the inability to recover the original substance indicate about a chemical change?

It is a permanent transformation into a different substance. Signup and view all the answers

Study Notes

Early Experiments to Characterize the Atom

The nuclei of elements other than hydrogen contain neutral particles with a mass similar to protons.
Robert Millikan conducted experiments using electrically charged oil droplets, allowing him to determine the charge of a single electron.
Physical changes can be reversed, like ice melting and freezing back into water.
Chemical changes cannot be reversed, like cooking a steak, as the raw meat cannot be recovered.

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Description

Explore the foundational experiments that helped characterize the atom, including Robert Millikan's work on the electron charge. Understand the differences between physical and chemical changes and their implications for matter. This quiz delves into key scientific principles vital to atomic theory.