Lesson 1.4: Atomic Emission Spectra & Bohr's Model

Flashcard set covering Bohr's model of the atom, emission and absorption spectra, energy level transitions, spectroscope function, and chemical laws.

What is the ground state of an atom?

The ground state is the lowest allowable or lowest possible energy level that an electron can occupy.

What occurs when an atom is in an excited state?

When an atom gains energy, an electron absorbs energy and moves to a higher energy level, placing the atom in an excited state.

Who proposed the 1913 atomic model that described electrons as moving in circular orbits around the nucleus?

Niels Bohr, a Danish physicist who correctly predicted the frequency lines in hydrogen's atomic emission spectrum.

What is a quantum of energy in the context of Bohr's model?

A quantum is the exact amount of energy required to move an electron from one energy level to another, representing the smallest amount of energy that can be gained or lost by an atom.

How do the principal quantum number ($n$) and electron position change during energy absorption?

During absorption, $n$ increases as the electron absorbs a photon and moves farther from the nucleus to a higher energy level.

What happens during energy emission by an excited electron?

During emission, $n$ decreases as the excited electron falls back closer to the nucleus, releasing energy as a photon of light with energy equal to the difference between the two energy levels.

To which energy levels ($n$) do electron transitions fall for the Lyman, Balmer, and Paschen spectral series?

The Lyman series (ultraviolet) drops to $n=1$, the Balmer series (visible) drops to $n=2$, and the Paschen series (infrared) drops to $n=3$.

What are the four characteristic visible spectral lines of hydrogen in the Balmer series?

Red line: $656.2\,nm$ ($n=3 \rightarrow n=2$); Blue-green line: $486.1\,nm$ ($n=4 \rightarrow n=2$); Blue-violet line: $434.0\,nm$ ($n=5 \rightarrow n=2$); Violet line: $410.1\,nm$ ($n=6 \rightarrow n=2$).

What is an atomic emission spectrum?

An atomic emission spectrum is the pattern of distinct colored lines formed when light emitted by excited atoms of an element is separated into its component wavelengths.

How does an absorption spectrum visually differ from an emission spectrum?

An absorption spectrum appears as a continuous spectrum (rainbow) with dark lines where light was absorbed, whereas an emission spectrum consists of discrete colored lines on a dark background.

How does a spectroscope separate light into individual colors?

A spectroscope passes light through a prism or diffraction grating, separating the light into individual colors based on their specific wavelengths.

Why is an atomic emission spectrum considered an elemental fingerprint unique to each element?

Each element has unique energy level spacings and electron arrangements, resulting in a unique pattern of emitted light wavelengths that no two elements share.

What is the maximum electron capacity of the first ($n=1$) and second ($n=2$) energy levels in Bohr's model?

The first energy level can hold a maximum of $2$ electrons, and the second energy level can hold a maximum of $8$ electrons.

What is the general sequence for filling atomic orbits with electrons?

The order of filling atomic orbits is $2, 8, 8, 18$.

Which element is present in the unknown sample based on the atomic emission spectra shown?

Strontium, because all of its spectral lines align exactly with those in the unknown sample's spectrum.

Which element is represented by this atomic diagram containing $11$ protons and $12$ neutrons?

Sodium ($\text{Na}$), because it has an atomic number of $11$.

In the provided atomic diagram, what type of electron is indicated by the label M?

Valence electron, as it is located in the outermost energy level.

What is the Law of Multiple Proportions?

When two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in a ratio of small whole numbers.

For compounds $\text{NO}$ ($14.0\,g\,\text{N}, 16.0\,g\,\text{O}$) and $\text{NO}_2$ ($14.0\,g\,\text{N}, 32.0\,g\,\text{O}$), what is the ratio of oxygen mass in $\text{NO}_2$ to $\text{NO}$?

The ratio is $\frac{32.0\,g}{16.0\,g} = \frac{2}{1}$ (or $2:1$), which is consistent with the Law of Multiple Proportions.

For the reaction $L + M \rightarrow N + T$, given $L=25.5\,g$, $M=15.0\,g$, and $N=10.0\,g$, what is the mass of $T$ using the Law of Conservation of Mass?

The mass of $T$ is $30.5\,g$, calculated as $T = (25.5\,g + 15.0\,g) - 10.0\,g = 30.5\,g$.

Why was Bohr's model unable to explain the emission spectra of elements other than hydrogen?

Bohr's model could not explain other elements because electrons do not actually move in fixed circular paths.

Which direction of electron transition results in the emission of light?

Transition from a higher energy level to a lower energy level ($n_i > n_f$).