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3. DATA ON THE ATOMIC STRUCTURE
Chemical element can exist in three formakh:svobodny atoms, simple substances, complex substances.
Let's talk about atoms. Atoms are the chemical particles which are limit of chemical decomposition of any substance. Atoms are not divisible in the chemical way.
The mass of atoms of different types makes порядка10-24-10-22г, the sizes of atoms fluctuate within 1·10-10-5·10-10 m therefore atoms are considered as the most fine chemical particles.
Atoms of one look are atoms of one chemical element, atoms of different types atoms of different chemical elements.
What atomic structure? On modern representations atom consists of positively charged kernel around which negative electrons rotate. The atomic structure can be presented in the form, so-called, planetary model which was offered by Ernest Rutherford. It represents mini-solar system where in the center there is kernel (Sun) around which electrons (the planet of solar system) rotate.
The ground mass of atom is concentrated in kernel which consists of particles of two types: protons and neutrons. Protons have the charge equal to elementary charge, but opposite on sign (+), and the weight equal to the mass of carbon or 1/12 mass of carbon (this unit is called atomic mass unit with which we will get acquainted later). Protons are designated by sign р +. Neutrons have no charge, that is they are elektroneytralna, and have weight approximately equal to the mass of proton, i.e. 1. Designate n0. The sum of number of protons and neutrons is called mass number. As atom электронейтрален, the number of protons and electrons in atom is identical. The mass of electrons can be neglected, it is possible to consider that all mass of atom is concentrated in kernel. We will learn to define number of protons and neutrons after we study the Periodic Table.
