Atoms for Dummies

What is an atom?
The term "atom" refers to the small portion of matter, the small brick building that serves all other bodies. The word itself comes from Greek and means "indivisible piece." The idea that matter is composed of a multitude of small invisible ball goes back to antiquity. But only in the late nineteenth century that science discovered the atom and structure. In fact, we now know that the atom itself is composed of several elements, and it is possible to divide it.

What makes up an atom?
An atom consists of a central core around which the electrons. These electrons form what gravity is called the electron cloud, or atomic cloud. The nucleus of the atom, also called the atomic nucleus is itself composed of protons and neutrons. The electrons orbit the nucleus due to electromagnetic force. Indeed, the electrons have a negative electrical charge, while the protons in the nucleus have a positive charge (neutrons are neutral). Thus, although they travel at tremendous speed, the electrons do not escape from the atom because they are attracted to the nucleus by protons (principle of the magnet).

Specifically, what looks like an atom?
Protons and neutrons weigh much heavier than electrons, so that 99.97% of the mass of the atom consists of its core. In terms of size, an atom is a tiny, with a diameter between 62 and 596 picometers (1 meter divided by 10 power 12). The core is still 40,000 to 100,000 times smaller. And as more electrons are tiny, most of the atom consists of empty ... If we removed all the air contained in the atoms, the Earth would in a sphere of 150 m. radius.

Chemical elements, isotopes and classification of atoms
All electrons, all protons and all neutrons are identical. Yet it exists in nature 90 different kinds of atoms chemical elements. In fact, the atoms differ from each other by their number of protons (atomic number). Thus, hydrogen has 1 proton, while the oxygen atom has 8. Today, there are also man-made elements such as plutonium, a radioactive element that has 94 protons. In addition, all chemical elements can be broken down into isotopes. This is the same chemical element, in which the number of neutrons is different. Thus, if an oxygen atom has 8 protons bound, it can have 8, 9 or 10 neutrons. Each of these variants is an isotope of oxygen. The chemical elements are designated by a letter (O for oxygen) and an atomic mass (number of protons + neutrons). Thus, the oxygen isotopes are denoted 16O, 17O and 18O.