| |
|
 |
| A man named 'Smalley' is meant to be a king of the Small world. He was. |
by TheAlieness GiselaGiardino�� on Flickr |
|
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons.
|
 |
| The Atomium (2) |
by o palsson on Flickr |
|
The electrons of an atom are bound to the nucleus by the electromagnetic force. Likewise, a group of atoms can remain bound to each other, forming a molecule.
|
 |
| Ethanol |
by wasoxygen on Flickr |
|
An atom is classified according to the number of protons and neutrons in its nucleus: the number of protons determines the chemical element, and the number of neutrons determines the isotope of the element.
|
 |
| a girl's best friend |
by gcfairch on Flickr |
|
Atoms can only be observed individually using special instruments such as the scanning tunneling microscope. Over 99.94% of an atom's mass is concentrated in the nucleus.
|
|
Electrons that are bound to atoms possess a set of stable energy levels, or orbitals, and can undergo transitions between them by absorbing or emitting photons that match the energy differences between the levels. The electrons determine the chemical properties of an element, and strongly influence an atom's magnetic properties.
|