#### Related to [[Atomic structure]] and [[General chemical concepts]] --- ## Definition - Quantum mechanics is a model to explain the behavior of light and matter at a subatomic scale. --- ## Wave function - The primary basis of quantum mechanics is something known as a *wave function.* - The *wave function* of a particle describes its **position and state**. --- ## What does *H* represent? - In quantum mechanics the letter H represents the **energy of the system** and takes into account many variables between one or two atoms. --- ## Other things described - Schrodinger and thus quantum mechanics revealed a *possible* reason for the specific *whole number* orbits of electrons around a nucleolus. Since [[Electrons]] are a wave they would **destructively interfere** with other orbiting electrons if they **didn't** have a whole number of wavelengths *(see image below)*. >[!quote] >##### *Electron interference* > >![[Electron interference 1.png]] --- ## Uncertainty - One fundamental aspect of quantum mechanics is the notion that one is unable to know with perfect precision both the position and momentum of a given particle at any point in time. This is known simply as the **Heisenberg uncertainty principle.** > [! Equation for the uncertainty principle] > <br> > > ![[Quantum mechanics uncertainty principle equation.png]] > > **Which can be rearranged like this to solve problems:** > <br> > > ![[Quantum mechanics uncertainty 2.png]] > > **Also recall:** > <br> > > ![[Quantum mechanics 4.png]] --- ## Wavelength according to quantum mechanics. - See information on DeBroglie's equation on the [[Electromagnetic radiation]] page. --- ## Square of a wave function - The square of a wave function shows the probability of a particle being at *a certain location.* The greater the waves' amplitude the greater the probability of that particle being there. - The shape of [[Orbitals]] are a **direct result** of the square wave function as is illustrated bellow for basic *s* orbitals. >[! Square root image] ><br> > > **Square root of wave function is graph on right:** > > ![[Squared wave function.png]] --- ## Polyelectronic atoms - Currently quantum mechanics can describe only monoelectronic atoms *(hydrogen)*. Polyelectronic atoms contain too many interacting forces and thus we have no way of mathematically describing them or their electrons. - As a result we cannot calculate the **exact** energies of orbitals in any atom **except hydrogen**. so we are forced to **estimate**. --- #mainpage