Electron behavior

Lesson 3.2 – Electron BehaviorLearning intentions: I am learning about the important electron structure discoveries made by scientists. Success Criteria: I can explain the movement of electrons within the atom as energy is absorbed and released. I can explain how an atomic emission spectrum provided evidence for Bohr's planetary model of the atom. Using the periodic table, I can identify how many occupied energy levels an atom has.

Atoms & EnergyLouis de Broglie was a French scientist who proposed that electrons are particles that can act aswavesS! Therefore, as atoms absorb and release energy, the electronso move within the atom.

Atoms & EnergyThe ground state of an atom exists when its electrons are in positions of the lowest possible amount of energy (normal). When an atom absorbs energy (often through heat, electricity, UV radiation, etc), the electrons jump to higher energy positions. This is known as the excited state of the atom.

Atoms & Energy The excited state of an atom is not stable. Atoms must release the extra energy absorbed, which allows the electrons to go back to the ground state. This release of energy is seen as LIGHT!

Quantization of EnergyScientists viewed the release of light from elements using a diffraction grating, which allowed the atomic emission spectrum for each element to be studied.

Atomic Emission Spectrum

Quantization of EnergyIn these spectra, separated bands of light at different wavelengths could be seen. This allowed Max Planck to conclude that atoms could only absorb and release energy in measurable amounts. Their energy is quantized. E = h(c/𝜆)

The Planetary Model Niels Bohr used the quantization of energy to propose the Planetary model of the atom. He believed the emission lines were the result of electrons moving among separated energy levels (aka shells) around the nucleus. Electrons could NOT move to the space between the energy levels.

The Planetary ModelThe periodic table is organized to show the arrangement of electrons in different energy levels The elements in the first period have electrons located in only 1 energy level The elements in the second period have electrons located in 2 energy levels, etc.

The Planetary ModelBohr proposed the energy levels around the nucleus were circular. However, this model was eventually rejected because only hydrogen has circular energy levels.