Molecular Structure.
Atoms, electrons, neutrons and protons

The atom What is it?

The atom What is it?

What is an atom? Imagine you have a piece of iron. The parts. You still have two pieces of iron but smaller. The you come from again ... Every time have smaller pieces until you reach a moment that if the seeming from what you would no longer be hiero.

At this point what is left is an atom, an iron atom.

Definition of atom

From a more formal way, we define as the smallest atom in an element can be divided without losing its chemical properties particle.

The origin of the word atom comes from the Greek, meaning indivisible. At the time that these particles were baptized they believed that they could not effectively divide, but today we know that atoms are made of even smaller particles, called subatomic particles.

Structure of an atom

Defining atom These subatomic particles with which they are formed atoms are threefold: the electrons, protons and neutrons. What differentiates one atom from another is the relationship established between them.

Electrons have a negative charge and are the lightest subatomic particles. The charge of protons is positive and weigh about 1,836 times more electrons. The only people who have no electric charge are neutrons which weigh about the same as protons.

Protons and neutrons are grouped in the center of the atom formed the atomic nucleus. For this reason it is also called nucleons. Electrons appear orbiting around the atomic nucleus.

Thus, the central part of the atom, the atomic nucleus has a positive charge in which almost all of its mass is concentrated, while the foreshortening, around the atomic nucleus, there are a number of electrons, negatively charged . The total charge of the atomic nucleus (positive) is equal to the negative charge of the electrons, so that the total electric charge is neutral atom.

Model of Bohr

This description of electrons orbiting the atomic nucleus corresponds to the simple Bohr model. According to quantum mechanics each particle has a wave function that occupies the entire space and the electrons are located in orbits although the probability of occurrence is higher at a certain distance from the nucleus.

properties of atoms

The basic units of chemistry are atoms. During chemical reactions the atoms are preserved as such, are not created nor destroyed, but are organized differently creating different links between an atom and another.

The atoms are grouped to form molecules and other types of materials. Each type of molecule is the combination of a number of atoms linked together in a specific way.

Depending on the composition of each atom represented different chemical elements in the periodic table of chemical elements differ. In this table we can find the atomic number and mass number of each item:

  • Atomic number, is represented with the letter Z indicates the number of protons having an atom, which is equal to the electron. All atoms with the same number of protons belong to the same element and have the same chemical properties. For example all atoms with a proton are hydrogen (Z = 1), all atoms with two protons are helium (Z = 2).
  • Mass number is represented by the letter A, and refers to the sum of protons and neutrons that contains the item. Isotopes are two atoms with the same number of protons but a different number of neutrons. Isotopes of the same element, have a chemical and physical properties very similar to each other.

Periodic table of elements. Features atoms.

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Last review: October 28, 2016