The structure of substances has been interesting to people since the opportunity arose not to worry about food and study the world around us. Such phenomena as droughts, floods, lightning, terrified mankind. Ignorance of their explanations gave rise to belief in various evil gods requiring sacrifices. That is why people began to study natural phenomena, striving to predict them, and delve into the structure of substances. They studied the structure of the atom and introduced the following two important concepts in chemistry: energy level and sublevel.
Prerequisites for the discovery of the smallest chemicals
The ancient Greeks guessed about the small particles that make up substances. They made a strange discovery: the marble steps, which many people have passed over several decades, have changed their shape! This led to the conclusion that the foot of the past takes some piece of stone with it. This phenomenon is far from understanding the existence of an energy level in chemistry, but precisely withit all started. Science began to progressively develop and delve into the structure of chemical elements and their compounds.
The beginning of the study of the structure of the atom
Atom was discovered at the beginning of the 20th century through experiments with electricity. It was considered electrically neutral, but had positive and negative constituent particles. Scientists wanted to find out their distribution inside the atom. Several models were proposed, one of which even had the name "raisin bun". British physicist Ernest Rutherford conducted an experiment that showed that the positive nucleus is located in the center of the atom, and the negative charge is in the small electrons revolving around it.
The discovery of the energy level in chemistry was a big breakthrough in the study of the structure of substances and phenomena.
During the study of the properties of chemicals, it turned out that each element has its own levels. For example, oxygen has one structure scheme, while nitrogen has a completely different one, although the numbers of their atoms differ only by one. So what is an energy level? These are electronic layers, consisting of electrons, which are formed due to the different strength of their attraction to the nucleus of an atom. Some are closer, while others are farther. That is, the upper electrons “press” on the lower ones.
The number of energy levels in chemistry is equal to the number of the period in the Periodic table of D. I. Mendeleev. The largest number of electrons that are in a given energy level is determined by the following formula: 2n2, where n is the level number.Thus, no more than two electrons can be located on the first energy level, no more than eight on the second, eighteen on the third, and so on.
Each atom has a level farthest from its nucleus. It is the extreme, or last, and is called the outer energy level. The number of electrons on it for elements of the main subgroups is equal to the group number.
To build a diagram of an atom and its energy levels in chemistry, you need to follow this plan:
- determine the number of all electrons of an atom of a given element, which is equal to its serial number;
- determine the number of energy levels by period number;
- determine the number of electrons in each energy level.
See below for examples of energy levels of some elements.
In atoms, in addition to energy levels, there are also sublevels. At each level, depending on the number of electrons on it, certain sublevels are filled. From how the sublevel is filled, four types of elements are distinguished:
- S-elements. The s-sublevels are filled, which can contain no more than two electrons. These include the first two items from each period;
- P-elements. In these elements, there can be no more than six electrons located on the p-sublevel;
- D-elements. These include elements of large periods (decades) located between s- andp-elements;
- F-elements. The filling of the f-sublevel occurs in actinides and lanthanides located in the sixth and seventh periods.