Atoms, Atomic Theory ,The Bohr Model

Atoms
When you think of an atom, you might picture a little solar system-like model with paths of electrons orbiting a centralized nucleus. This is the early atomic model that Niels Bohr and other scientific pioneers envisioned many years ago. But thanks to experimental advancements and some modern-day thinkers, like Erwin Schrodinger and Werner Heisenberg, we now believe that electrons look more like clouds than neatly orbiting planets. This new idea of what atoms look like is the basis of the modern atomic theory. Let's take a look at how science advanced from its early understanding of atoms to the modern view of today.

Atomic Theory
Scientists have known about atoms long before they could produce images of them with powerful magnifying tools. In fact, atoms get their name from the Ancient Greek word atomos, which means 'something that is not able to be divided'.

Because atoms could not be seen, the early ideas about atoms were mostly founded in philosophical and religion-based reasoning. Near the end of the 18th century, new ways to conduct experiments helped researchers build their scientific understanding of atoms. This lead to the first atomic theory, which stated things like, all matter is made up of atoms, elements are composed of only one type of atom, and atoms can combine with other atoms to make more complex substances.

This first atomic theory explained a lot, but as science continued to advance, new information and new discoveries made it clear that the theory needed to be updated. One of these new discoveries came at the end of the 19th century, with the discovery of a subatomic particle, called an electron. The word 'subatomic' literally means 'inside an atom'. Because of this discovery it became clear that atoms might not have been named correctly and that they could be divided into smaller parts.

When electrons were first discovered, scientists knew they were part of the atom, but they didn't know where they belonged. At first the thought was that electrons floated throughout the atom, like pieces of fruit floating in pudding, as if the atoms were simply soft blobs of matter. But, through more experimentation, it was found that most of the matter within atoms is centralized. By the early 20th century, this centralized matter came to be recognized as the nucleus of the atom.

The Bohr Model
In 1913, a scientist by the name of Niels Bohr expanded on all of the past research about atoms, and came up with the idea that negatively charged electrons orbit a positively charged nucleus in definite paths. This concept came to be known as the Bohr model. This was the first real look at the solar system-like model of an atom that we mentioned at the beginning of this lesson.