Lab: Atomic Spectra

According to the quantum theory of the atom, electrons are found in regions of space around the atomic nucleus called orbitals which are associated with a particular energy level and can hold a certain maximum number of electrons. The distribution of electrons in these orbitals determines the chemical properties of the element.

The "ground state" of an electron refers to the lowest energy level or state that an electron can occupy within an atom. When an electron is in the ground state, it is at its most stable and has the lowest possible energy.

Electrons can become "excited" when they absorb energy from an external source such as light, heat, or electricity. When an electron absorbs energy, it gains the energy required to move from its ground state to a higher energy level or excited state. This process is called excitation.

When excited electrons return to the ground state, they usually emit energy in the form of "light". The emitted light has a wavelength and frequency corresponding to the energy difference between the excited state and the ground state.

Bohr’s Atomic Model

• https://javalab.org/en/bohrs_atomic_model_en/ 

Structure of an Atom

• https://javalab.org/en/structure_of_an_atom_en/ 

Hydrogen Atom: Energy Levels in the Quantum Model:

• https://ophysics.com/m1.html 

Emission and absorption spectra are two types of spectra that are used to study the interaction of light with matter, particularly with atoms and molecules.

What is an Emission Spectrum?

• When energy is absorbed by electrons of an atom, electrons move from lower energy levels to higher energy levels. An emission spectrum is a spectrum of light released by an atom or molecule when its electrons drop from higher energy levels to lower ones. 

How are atomic spectra used to determine the chemical makeup of stars?

• Atomic spectra are essential for determining the chemical makeup of stars through a process called spectroscopy. When scientists observe the light emitted by a star, they pass it through a spectroscope to separate it into its spectrum. Both emission and absorption spectra appear, with absorption lines being more common in starlight due to the star’s outer layers absorbing certain wavelengths.

• https://www.astronomy.ohio-state.edu/pogge.1/TeachRes/HandSpec/atoms.html 
• http://personal.psu.edu/a0j/periodic4.html 

What is the Absorption Spectrum?

• An absorption spectrum is a spectrum that shows which wavelengths of light are absorbed by a substance, typically an atom or molecule. When light passes through a sample of atoms, certain wavelengths are absorbed as the electrons in the atoms gain energy and move to higher energy levels. This absorption appears as dark lines or gaps within the otherwise continuous spectrum of light.

An emission spectrum is produced when electrons in excited atoms or molecules return to their ground state and emit photons of light in the process. The emitted photons have a specific energy and wavelength corresponding to the energy difference between the excited state and the ground state. Each element has a unique set of energy levels that are associated with specific wavelengths of light that can be emitted. The emission spectrum of an element is like its "fingerprint" and can be used to identify the element.

An absorption spectrum, on the other hand, is produced when a sample of matter absorbs photons of light. The absorbed photons have the same energy and wavelength as the emitted photons in the corresponding emission spectrum. However, in the absorption spectrum, some of the wavelengths of light are missing, or "absorbed," because they were absorbed by the atoms or molecules in the sample. The absorption spectrum of a sample can be used to identify the chemical composition of the sample, as different compounds and elements absorb light at different wavelengths.

Both emission and absorption spectra are important tools in spectroscopy, which is the study of the interaction between light and matter. They are used in a wide range of fields, including chemistry, physics, astronomy, and environmental science, to identify and analyze the composition of samples, to determine the energy levels of atoms and molecules, and to study the physical and chemical properties of matter.