What Makes up an Atom?

Have you ever been asked in science class what makes up an atom? Atoms are the smallest part of an element, and are the building blocks of nature. All people are composed, at the microscopic level, of atoms. Beyond this, however, how much do you really know about these blocks of matter? If atoms make up everything else in the world, then what makes up an atom?

Atoms are made up of three different types of particles. These particles are protons, neutrons, and electrons. The majority of an atom is composed of protons and neutrons.

For example, if you had one hundred marbles in a bowl, protons and neutrons would be responsible for ninety-nine out of the one hundred marbles. A proton has a positive charge, a neutron has a neutral charge, and an electron has a negative charge.

Structure of an Atom

Now that you know what makes up an atom, what is the structure? The structure of an atom is a nucleus, and then a series of orbital circles that surround this nucleus. The protons and the neutrons reside in the nucleus of an atom. The electrons are in the orbitals that circle the nucleus.

The amount of protons in the nucleus of an atom determines its atomic number. The atomic number is simply a way of identifying different atoms from one another, and it is the amount of protons in the atom.

Since the protons are positively charged, the atomic number and the charge number of the nucleus are identical numbers. For example, the atomic number of Hydrogen is one. This means there is one proton in Hydrogen’s nucleus. The mass number of an atom refers to the sum of the protons and neutrons in an atom’s nucleus.

This amount of neutrons in an atom does not always remain stable, thus the mass number of types of atoms can differ. When the same type of element differs in the amount of neutrons it contains, the differing types are referred to as “isotopes.” The chemical components of isotopes of the same element are identical; the isotopes merely differ in their physical properties.

Atom Orbitals

Atoms seek to have complete outer orbitals. An atom may have a first orbital of one electron, then a second ring of two electrons, and then a third ring that can hold three electrons.

A different type of atom might have the three rings that are capable of holding five, then six, then seven electrons. An atom seeks to have its rings completed (filled to their capacity with electrons). By losing, sharing, or gaining electrons, the atom is able to accomplish this.

The simplest form of the atom is described above. This is the structure of an atom with a nucleus, and orbitals that circle it. This structure is similar to the solar system structure, with planets circling the sun. This model is called the Bohr Model of the atom, and it explains the simplest forms of the atom.

Electrons can move from one orbital of energy to the next orbital of energy, but the electrons can only exist in definite energy levels. Further, the energy in the atom is absorbed or released only when electrons change their states into electromagnetic radiation.

Complex Atoms

However, this model only explains the simplest atoms. An atom with a very low atomic number, such as the Hydrogen example above, can be explained by the Bohr Model.

However, as atoms become more complex and larger, the wave model and quantum theory must be used to explain where the electrons will be. These models are based upon physics and mathematics, and can be quite complicated to understand. These models are based on calculating the probability that an electron will be in a given location.

In these models, the electrons don’t orbit the nucleus in neat and tight circles as in the Bohr Model. Rather, since these atoms are more complicated, the location of the electrons is more difficult to predict.