(II) The threshold wavelength for emission of electrons from a given surface is $320 \mathrm{~nm}$. What will be the maximum kinetic energy of ejected electrons when the wavelength is changed to (a) $280$$$\mathrm{~nm}$,

In a normal atom, how many electrons are there compared with protons?

The mass of one electron is $9.11 \times10^{28}$ grams. A uranium atom contains $92$ electrons. Find the total mass of the electrons in a uranium atom. Express your answer in scientific notation.

A(n) _ is formed when atoms share one or more electrons.

A glass is charged to $+ 5.0 \mathrm { nC }$ by rubbing. a. Have electrons been removed from the rod or protons added? Explain. b. How many electrons have been removed or protons added?

What is the total charge of all the electrons in a $15-\mathrm{kg}$ bar of gold? What is the net charge of the bar? (Gold has 79 electrons per atom and an atomic mass of 197 u.)

Indicate the number of valence electrons in F, Cl, Br, and I.

Which of the following best describes an electric conductor

• a. It prevents electron flow.

• b. It can retain a static charge.

• c. It holds electrons on its surface.

• d. It allows electrons to travel freely.

Determine the total number of valence electrons for $\mathrm{SBr_2}$.

One way to measure ionization energies is ultraviolet photoelectron spectroscopy (PES), a technique based on the photoelectric effect. In PES, monochromatic light is directed onto a sample, causing electrons to be emitted. The kinetic energy of the emitted electrons is measured. The difference between the energy of the photons and the kinetic energy of the electrons corresponds to the energy needed to remove the electrons (that is, the ionization energy) . Suppose that a PES experiment is performed in which mercury vapor is irradiated with ultraviolet light of wavelength 58.4 nm. The kinetic energy of the emitted electrons is measured to be $1.72 \times 10 ^ { - 18 } \mathrm { J }.$ What is the first ionization energy of Hg, in kJ /mol?

You determine that the maximum wavelength of the light needed to eject electrons from the surface of a certain metal is 683 nm. What is the wavelength of the light if the potential needed to stop ejected electrons is 0.8 V?

(II) The threshold wavelength for emission of electrons from a given surface is $320 \mathrm{~nm}$. What will be the maximum kinetic energy of ejected electrons when the wavelength is changed to (b) $360 \mathrm{~nm}$ ?

What is the total charge in coulombs of 75.0 kg of electrons?

How many valence electrons does Rn have?