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Questions and Answers

What method did Millikan use to create microscopic oil droplets?

Electrolysis

Vaporization

Atomizer or spray bottle (correct)

Centrifuge

What fundamental charge did Millikan determine through his experiment?

1.6 x 10^-19 C (correct)

1.759 x 10^11 C

1.602 x 10^-19 C

9.107 x 10^-31 C

How did changes in the electric field affect the motion of the oil droplets in Millikan's experiment?

It had no effect on their motion.

It increased their downward speed only.

It stabilized their position without change.

It could reverse their upward movement. (correct)

What type of rays did Goldstein discover in his experiments with cathode-ray tubes?

Canal rays Signup and view all the answers

What did Goldstein conclude these canal rays were composed of?

Positively charged particles Signup and view all the answers

Who put forth the nuclear model of the atom based on experiments in 1911?

Ernest Rutherford Signup and view all the answers

What was the charge-to-mass ratio determined by Thomson prior to Millikan's work?

1.759 × 10^11 C/kg Signup and view all the answers

What calculation did Millikan perform to determine the mass of the electron?

Mass = Charge / (Charge-to-Mass Ratio) Signup and view all the answers

What did Chadwick claim about the unknown radiation observed in his experiment?

It was actually neutral particles. Signup and view all the answers

How is the atomic number of an element defined?

The number of protons in the nucleus. Signup and view all the answers

Which statement about isotopes is correct?

Isotopes can be separated by mass spectrometry. Signup and view all the answers

What does the mass number (A) of an atom represent?

Total number of protons and neutrons in the nucleus. Signup and view all the answers

What is the equation used to calculate the mass of an atom (ma)?

ma = Z * mp + N * mn Signup and view all the answers

In a neutral atom, how are the number of protons related to the number of electrons?

They are equal in number. Signup and view all the answers

Which of the following statements is true regarding atomic charge?

Atomic charge is the difference between protons and electrons. Signup and view all the answers

How is the mass of a neutron compared to that of an electron?

It is 1838 times higher. Signup and view all the answers

What is the molar mass of Carbon calculated using the natural abundances of its isotopes?

12.02 g/mol Signup and view all the answers

What is the relationship between mass defect and binding energy in a nucleus?

Binding energy is proportional to mass defect Signup and view all the answers

Which of the following equations represents mass-energy equivalence?

E = ∆mc^2 Signup and view all the answers

What is the energy equivalent of 1 electron volt in Joules?

1.602 × 10^-19 J Signup and view all the answers

How is the charge in Coulombs calculated using current and time?

q = I × t Signup and view all the answers

What did William Crookes discover through his discharge tube experiments?

Cathode rays are made up of negatively charged particles. Signup and view all the answers

Which characteristic of cathode rays does not support the idea that they consist of particles?

They emit light when they hit a fluorescent material. Signup and view all the answers

In J.J. Thomson's experiment, what does the measure of e/m refer to?

Electric charge per mass of an electron. Signup and view all the answers

What happens when a rotor blade is placed in the path of cathode rays, according to Crookes' findings?

The blades rotate, indicating kinetic energy. Signup and view all the answers

What conclusion can be drawn from the fact that cathode rays are deflected towards the positive plate in an electric field?

They are negatively charged particles. Signup and view all the answers

What fundamental concept regarding electrons did George Stoney contribute?

He coined the term 'electron.' Signup and view all the answers

Which factor is NOT involved in determining the mass of particles in the equation $m = M * I * t / n * F$?

Voltage (V) Signup and view all the answers

What is the purpose of using low pressure in the Crookes tube?

To prevent the gas from blocking the current. Signup and view all the answers

What was the major finding from Rutherford's experiment with gold foil and alpha radiation?

Most alpha particles passed through without being scattered. Signup and view all the answers

What significant concept about atomic structure did Rutherford's model introduce?

Most of the atom's mass is concentrated in the nucleus. Signup and view all the answers

What is the mass of a proton based on the content provided?

1.6726 x 10-27 kg Signup and view all the answers

Which particle was discovered by James Chadwick in 1932?

Neutron Signup and view all the answers

What was the initial hypothesis about the particles produced when Chadwick bombarded beryllium with alpha particles?

They were high-energy gamma radiation. Signup and view all the answers

How do the diameters of atomic nuclei compare to the overall size of an atom?

Nuclei are a hundred thousand times smaller than atomic diameters. Signup and view all the answers

What role does the lead plate play in the setup of Rutherford's experiment?

It absorbs the alpha radiation. Signup and view all the answers

Which statement about alpha particles is accurate based on the content provided?

They are helium nuclei. Signup and view all the answers

What did J.J. Thomson primarily measure to determine the properties of electrons?

The deflection of cathode rays in magnetic and electric fields Signup and view all the answers

What was the key finding regarding the mass-to-charge ratio (e/m) of electrons from Thomson's experiments?

It is independent of the material used in electrodes Signup and view all the answers

In Thomson's experiment, what physical force is neglected besides the electric force when analyzing electron motion?

Gravitational force Signup and view all the answers

What relationship does the equation E = Bv0 demonstrate in Thomson's experiment?

The balance between electric and magnetic forces Signup and view all the answers

How is the acceleration of electrons represented in relation to the mass and charge in Thomson's equations?

a = eE/m Signup and view all the answers

What was the main outcome of Millikan's oil drop experiment conducted in 1909?

Measurement of the charge of the electron Signup and view all the answers

What does the symbol |e|/m represent in the context of the content?

Charge-to-mass ratio of an electron Signup and view all the answers

Which of the following equations correctly relates the deviation y0 to the mass-to-charge ratio in Thomson's experiment?

y0 = ½(eE/me)(L/v0)^2 Signup and view all the answers

Study Notes

Introduction to Matter

Democritus proposed that all matter is composed of indivisible particles called "atomos" in the fifth century B.C.
John Dalton formulated a precise definition of atoms in 1808, stating that all matter is composed of small particles called atoms.

Composition of Atoms

Atoms are not the smallest particles, but are made of subatomic particles.
Subatomic particles, including electrons, protons, and neutrons were discovered in the late 1800s to early 1900s.

Discovery of Electrons

Faraday's laws of electrolysis highlighted a relationship between matter and electricity.
Faraday's laws demonstrated that chemical reactions occur when electricity is passed through an electrolyte, liberating matter at the electrodes.
Crookes' experiments with cathode rays showed the existence of negatively charged particles (electrons) that travel from the cathode to the anode.

Characteristics of Electrons

J.J. Thomson's experiments measured the charge-to-mass ratio of electrons (e/m).
This ratio was consistent regardless of the cathode material or gas used, suggesting electrons are a fundamental component of all atoms.

Electron Charge

Robert Millikan's oil-drop experiment determined the fundamental charge of an electron.
Millikan's experiment successfully determined the charge of an electron.
The charge-to-mass ratio of electrons and the fundamental electron charge, enabled scientists to calculate the electron mass.

Nucleus and Nucleons

Goldstein's discovery of canal rays provided evidence for positively charged particles (protons) inside atoms.
Rutherford's gold foil experiment demonstrated the nuclear model of the atom, showing that most of the atom's mass is concentrated in a small, dense nucleus.
Chadwick's experiment discovered neutrons, neutral subatomic particles with a mass similar to protons.

Nucleons and Atomic Structure

Protons and neutrons residing within atomic nuclei are called nucleons.
The atomic number (Z) represents the number of protons in an atom.
The mass number (A) represents the total number of protons and neutrons in an atom.
Atoms with the same number of protons but different numbers of neutrons are isotopes.

Atomic Mass

The mass of an atom (ma) is primarily determined by the total mass of its protons and neutrons (nucleons).
Atomic mass is approximately equal to the mass number (A).

Isotopes

Atoms with the same atomic number but different mass numbers are called isotopes.
Isotopes have similar chemical properties.
Isotopes can be separated based on their differences in mass.

Binding Energy

The mass of the nucleus is less than the mass of its constituent protons and neutrons.
This difference, called the mass defect, is converted into the binding energy of the nucleus.
Binding energy is the energy required to break the nucleus into its constituent protons and neutrons.

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