The appearance in 1911 of Rutherford planetary model and its application in physics and chemistry should have helped to understand and answer a difficult question about the structure of matter. Subsequent updating of the atom model with the attraction of quantum mechanics appeared (Bohr, Sommerfeld, de Broglie, Heisenberg, Schrödinger and others) did not give clarity in the understanding of atomic structures development and atoms formation and, in particular, in the mechanism of electron shell filling. It should seem that knowing the structure of atom it is possible to determine and establish the structure of molecules and further of any substance. However, there is still an unsolved problem about how the bond between atoms exists, or what the nature of the chemical bond is. Analysis of the vast material accumulated by science about the structure and properties of various materials and various phenomena associated with them revealed many unclear issues. There is no answer to several questions regarding the structure and properties of atoms as well.

Here are just some of them:

• What is the role of neutrons in atoms?
• How does the electronic layers filling go?
• If the configuration of eight electrons (oktet) is the most stable state, which have inert gas atoms, then how can one explain inactivity the helium atom which has only two electrons;
• Carbon atom has unique properties: its valence is always constant and equal to 4. why does it never change its valence, i.e. does not form coordination compounds and does not form H-bonds?
• Why do all four corners of carbon atoms between valence bonds with other atoms are equal among themselves and equal to 109°28′ (tetrahedral angle)?
• What is an electropositive and an electronegative atom;
• Why is there a tug of an electron from one atom to another under normal conditions, i.e. why are ions formed under normal conditions?
• What is a coordination bond and what does determine the value of coordination number, i.e. how many ligands can bind one or another atom?
• Why does, for example, nitrogen very rarely change its valence and phosphorus - often, and so on?

Answers to these questions can be found in the author's monograph

"A crystal model of atom structure. The nature of chemical bond" (second edition, revised and broadened)