Bohr Model скачать в хорошем качестве

Bohr Model

Need help preparing for the General Chemistry section of the MCAT? MedSchoolCoach expert, Ken Tao, will teach everything you need to know about the Bohr Model for Electronic Structure. Watch this video to get all the MCAT study tips you need to do well on this section of the exam! The Bohr model, devised in the early 20th century by Danish physicist Niels Bohr, was one of the first models to predict how different subatomic particles were arranged to form an atom. It is based around the premise that protons and neutrons are located within a nucleus at the centre of the atom, and that electrons follow circular orbits at a distance around the nucleus. Like many historical models, the Bohr model proved to be incomplete and was eventually supplanted by more sophisticated models, but it still made several lasting contributions to our understanding of atomic structure. In particular, the Bohr model is responsible for the formulation of electrons orbiting within predefined shells, each moving away from the nucleus at a predictable rate and become increasingly higher in energy. In the Bohr model the first shell, located closest to the nucleus, would be the lowest energy, and thus most stable, shell of electrons, and each successive electron shell would be of progressively higher energy and lower stability. Bohr also predicted that the relative gap between each shell would decrease with distance from the nucleus, meaning that the empty space between the first and second electron shells would be greater than the space between the second and third shells, which would in turn be greater than the space between the third and fourth shells, and so on. Likewise, we could say that the gap in energy, as well as space, decreases with each successive shell. Additionally, the Bohr model states that each electron shell can be quantized, meaning that each electron within a shell has a specific, measurable (i.e. quantifiable) energy level, comparable to the energy of any other electron in that shell. Further, every possible electron orbital exists within these quantified electron shells, meaning that no electrons can exist in the gap between shells. These shells can be numbered successively suing the principal quantum number, n, with each shell increasing the quantum number by one. That is, the first electron shell, closest to the nucleus, has a principal quantum number (n) of one, while the second shell would have a principal quantum number of two, and continuing on in that manner to whatever the highest electron shell is for any particular atom. Excitation and Relaxation While an electron must exist within any particular shell at any given time, it is not necessarily bound to that shell. An electron at rest always assumes residence in the lowest available electron shell, meaning the lowest shell that has an available orbital for an electron to occupy. We call this the electron’s ground state, or resting state. However, an electron can, in certain instances, gain energy and ascend to a higher energy shell. This is called excitation, and results in the electron assuming the excited state, meaning that one or more electrons are now orbiting in a higher electron shell while orbitals are open at a lower energy shell. Note that, because the electron is in a higher energy state, it is also in a more unstable state. Because of this, these electrons will eventually descend back to their ground state, in a process called relaxation. During electron relaxation, the atom will releases the built up energy of the excited electron, emitting it in the form of a photon, or a particle of light or electromagnetic radiation. . Photon Absorption As you may have guessed from relaxation releasing a photon, the energy needed to excite an electron is provided when the electron absorbs a photon. The absorption of light by electrons was a key component of piecing together mathematical underpinnings of the photoelectric effect, a groundbreaking discovery in quantum physics for which Albert Einstein was awarded the Nobel Prize. While the quantum mechanics of the absorption of photons by electrons it is mostly beyond the scope of the MCAT, it is important to know that, since electrons can only exist in certain quantified energy shells, an electron can only absorb a photon if the energy of the photon is exactly enough to propel it from one energy shell to the next. MEDSCHOOLCOACH To watch more MCAT video tutorials like this and have access to study scheduling, progress tracking, flashcard and question bank, download MCAT Prep by MedSchoolCoach IOS Link: https://play.google.com/store/apps/de... Apple Link: https://apps.apple.com/us/app/mcat-pr... #medschoolcoach #MCATprep #MCATstudytools