The structure of substances has been interesting to people since the time when it became possible not to worry about food and to study the world around us. Such phenomena as droughts, floods, lightning, horrified humanity. Ignorance of their explanations gave rise to faith in various evil gods requiring sacrifice. That is why people began to study natural phenomena, seeking 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: the energy level and sublevel.
Background to the discovery of the smallest chemicals
The ancient Greeks guessed about the small particles that make up the substance. They made a strange discovery: the marble steps, over 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 him. This phenomenon is far from understanding the existence of an energy level in chemistry, but it was with it that it all began. Science began to progressively develop and deepen into the structure of chemical elements and their compounds.
Beginning of the study of the structure of the atom
At the beginning of the 20th century, through experiments with electricity, an atom was discovered. It was considered electrically neutral, but had positive and negative composite particles. Scientists wanted to find out their distribution inside the atom. It was proposed several models, one of which even had the name "bun with raisins." The British physicist Ernest Rutherford conducted an experiment which showed that a positive nucleus is located in the center of an atom, and a negative charge is located in small electrons orbiting around it.
The discovery of the energy level in chemistry was a major breakthrough in the study of the structure of substances and phenomena.
Energy level
In the course of studying the properties of chemicals, it turned out that each element has its own levels. For example, oxygen has one structural structure, and nitrogen has a completely different structure, although their atom numbers are only one unit different. So what is the energy level? These are electron layers consisting of electrons, which are formed due to the different forces 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.
The number of energy levels in chemistry equals the period number in the Periodic Table of D. I. Mendeleev. The largest number of electrons that are at a given energy level is determined by the following formula: 2n 2 , where n is the level number. Thus, at the first energy level no more than two electrons can be located, at the second - no more than eight, at the third - eighteen and so on.
Each atom has a level located farther from the others from its nucleus. It is the last, or last, and is called the external 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 the atom of a given element, which is equal to its ordinal number;
- determine the number of energy levels by the period number;
- determine the number of electrons at each energy level.
See below for examples of patterns of the structure of energy levels of some elements.
Energy sublevels
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. Four types of elements are distinguished from how a sublevel is filled:
- S-elements. The s-sublevels are filled, on which there can be no more than two electrons. These include the first two elements 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) between s- and p-elements;
- F-elements. The filling of the f sublevel occurs in actinides and lantonoids located in the sixth and seventh periods.