Modern Physics

Which of the following particles is NOT located in the nucleus of an atom?

In the Bohr model, the electric force between the electron and the nucleus is balanced by what?

An atom of lithium has a nuclear notation of $^7_3Li$. How many neutrons does this atom have?

An electron transitions from a higher energy level to a lower energy level in a hydrogen atom, emitting a photon. If the energy difference between the levels is $E$, and the wavelength of the emitted photon is $\lambda$, what is the relationship between $E$ and $\lambda$?

An electron in a hydrogen atom transitions from energy level $n = 3$ to $n = 1$. Given that the energy of the electron in the $n$th level is $E_n = -\frac{13.6 \text{ eV}}{n^2}$, calculate the energy of the emitted photon.

Consider a hypothetical atom with three energy levels: $E_1 = -10 \text{ eV}$, $E_2 = -5 \text{ eV}$, and $E_3 = -2 \text{ eV}$. An electron can transition between any two levels. Which transition will result in the emission of a photon with the shortest wavelength?

What is the atomic number of an element, and why is it significant?

Carbon-12 ($^{12}_{;6} ext{C}$) and Carbon-14 ($^{14}_{;6} ext{C}$) are isotopes of carbon. How many more neutrons does Carbon-14 have compared to Carbon-12?

According to Bohr's atomic model, what is a fundamental property of electron energy levels?