The Basics of Quantum Mechanics

I'm finally back again for this new post! I'm going to be explaining quantum mechanics in the simplest way possible.

First, I will start of with some atomic theory history. In the early 1900s, Ernest Rutherford came up with the planetary model of the atom, which is the one that is familiar to us today, although it is incorrect. The model could not explain: the electron collapse problem, periodic trends, and atomic line spectra.

The Danish physicist Neils Bohr applied the newly developed quantum idea (Max Planck) to the hydrogen atom. The quantum idea states that light travels as a packet of energy called a quantum. The electrons of a hydrogen atom are found in energy levels outside the nucleus called shells, and the electrons could only be found in these energy levels. They would not fall into the nucleus. Energy levels were designated by the principal quantum number, n. Using this model, Bohr was able to explain the atomic line spectra for the hydrogen atom.

Unfortunately, the Bohr Model could only explain the atomic line spectrum for elements with one electron. The quantum mechanical model began to emerge.

Bohr Model of the atom

In 1929, Louis de Broglie derived the de Broglie wave equation. The wave equation could be applied to all systems, but is only detectable for very small objects.

The Heisenberg Uncertainty Principle states that it is not possible to know the exact position and momentum of an electron at the same time.

The Schrödinger Wave Equation describes the behaviour and energy of electrons. It is denoted by the Greek letter psi. Psi^2 is the probability of finding an electron in a particle region of space. This equation can only be solved for systems with one electron. All others are approximated. The solutions to the equation yields the quantum numbers, used to describe the most probable location of the electron in the atom.

I'm afraid that will be it for now
. In the next post (which will hopefully be in a few hours), I will describe the quantum numbers and laws associated with them!

Mole Day

Yes. I know Mole Day was a few days ago (October 23), but it isn't too late to celebrate!

Mole Day was created in recognition of the amazing unit of measurement, the mole (6.022x10^23), also known as Avagadro's number. The mole was named in honor of Italian chemist, Amedeo Avagadro. (The picture below is just so funny!)

The mole is very important in chemistry, and it is 6.022x10^23 of anything. Imagine a book with that many pages!

With these few little facts, happy late Mole Day!

Methods of Fossilization

Sorry for not posting anything for so long! Now we're completely switching gears.

This time I'll be talking about methods of fossilization. Before that, though, I need to tell you some of the conditions for fossilization. It is very difficult for an organism to become fossilized, because the conditions are so specific.

Conditions for Fossilization:
1. Conditions are mild.
2. Composition of the organism is suitable for fossilization (usually hard parts, but not always).
3. Remains of the organism are buried quickly.

These are just some, not all of the conditions, but they will suffice for now.

The Methods of Fossilization:

Common Modes-
1. Permineralization: Minerals from a solution fill into pores in wood, shell, or bone that eventually harden. A specific form of this is petrification where organic matter is replaced by minerals and eventually turns to stone. A well-known example of this is petrified wood.




2. Mold: Imprints of an organism in rock.
    Cast: A replica of the original organism when the mold is filled with sediments or minerals. This is relatively uncommon.






3. Carbonization: Usually fossilizes plants and soft-bodied animals. Organisms fossilized as a carbon film in sediment.
May show great detail.






4. Actual Remains: Is what it sounds like. Organism's original body somehow survives.







5. Amber/Copal: Organism is trapped in pine resin which turns into amber. Soft parts are fossilized.

6. Mummification: Just as it sounds. An organism is mummified in natural conditions.







7. Freezing: One thing that may cause mummification. Organism is frozen and preserved.





8. Entrapment in tar/asphalt: Organisms are trapped in tar or asphalt and preserved.







These are, of course, not all of the methods of fossilization, but some of the most common. The processes described here also take a very long time.

The Action Potential-An Electrical Signal

The nervous system is a wondrous thing. It is what makes your body function, gives you your senses, helps with that upcoming test, and more. The nervous system consists of the central nervous system, the brain and spinal cord, and the peripheral nervous system, everything else. We will focus on the peripheral nervous system for now.

Nerves (bundles of neurons) make up the peripheral nervous system. This system helps you receive external stimuli, such as when you touch something. These stimuli are received by neurons and transported to other neurons and so on until the signal becomes weak and eventually stops.

In order to understand these signals, we must first describe the neuron, a nerve cell. The neuron consists of four main parts. The cell body houses the nucleus and other organelles.  The dendrites carry signals to the cell body. The axon conducts signals toward and effector cell or another neuron. The myelin sheath, which only vertebrates have, makes a signal travel faster along the axon, because it has to jump around from the nodes of Ranvier, the only places on a neuron where a signal can be transmitted. The myelin sheath is a chain made up of Schwann cells. The synaptic knobs (in this diagram, the axon terminal) transmit signals from one neuron to another or to another neuron. A signal can only travel in one direction, from the dendrites to the synaptic knobs.

Neuron

The neuron is usually at resting potential, -70 mV (millivolts). The neuron's membrane keeps potassium and dissolved proteins (which have a negative charge) inside and sodium (positive charge) outside. Channels and pumps in the membrane also keep the charge stable at resting potential. Sodium-potassium pumps are a form of active transport. Sodium cells and forced out, and potassium cells are forced in. They move more sodium than potassium.

Finally, we can proceed to the action potential, also known as a nerve signal!

A neuron receives an external stimulus, and immediately the resting potential changes. The stimulus causes sodium channels to open, so the inside of the cell becomes more positively charged than before. If the threshold potential (-55

mV) is met, then an action potential is reached. More sodium channels open, and the inside of the cell becomes increasingly positive. This is called depolarization.

After the action potential is reached, sodium gates close, and potassium gates open. This causes the cell to become negative again. This is repolarization. There is a brief undershoot, because potassium channels close slowly. This is hyperpolarization. The cell is once again at resting potential.

The neuron will have short period where it is unable to receive another action potential. When an action potential occurs in one part of a neuron, it stimulates the next section of the axon and the next and the next. 

Propogation of an Action Potential Down an Axon

And now imagine. All of this has happened in just a few milliseconds!

Welcome!

Science is an art just as much as it is a 
technical subject. One must experiment with different things and ideas. There is infinite beauty in it. We will explore many scientific topics in this blog.So, if you're up for it, hop along and join the ride!  Buckle up, we're departing!