Sulfur (lat. Sulfur) is a non-metal element. The chemical symbol is S, the serial number in the periodic table is 16. The valency of sulfur was established even before the study of the structure of the atom. Its value was determined on the basis of the property to replace, attract or attach a certain number of other atoms or groups. Later, researchers figured out the role of negatively charged particles (electrons) in the formation of a chemical bond.
Valence of sulfur: what features of atoms affect its value?
In terms of prevalence on Earth, a chemical element is in 16th place. It occurs as bright yellow crystals or powder in rocks, near active and extinct volcanoes. The most famous natural compounds are sulfides and sulfates.
Features of the element and substance:
- Strong non-metal.
- In terms of electronegativity (EO), or the ability to attract electrons, sulfur is second only to fluorine, oxygen, nitrogen, chlorine and bromine.
- Interacts with metals and non-metals, simple and complex substances.
Differences in properties depend on the structure and state of the atom, the difference in the values of EO. Let's find out what valence sulfur can have in compounds. Their chemical behavior depends on the structure of the energy shells, the number and arrangement of outer electrons in the atom.
Why does valence vary?
Stable are the natural isotopes of sulfur with mass numbers 32 (most common), 33, 34 and 36. Each of these nuclides contains 16 positively charged protons. In space near the nucleus, 16 electrons move with great speed. They are infinitesimal, negatively charged. Less attracted to the nucleus (more free) 6 outer particles. Several or all of them take part in the formation of different types of chemical bonds. According to modern concepts, the valence of sulfur is determined by the number of created common (bonding) electron pairs. Usually, in drawings and diagrams, the external particles that take part in this process are depicted as dots around the chemical sign.
How does valence depend on the structure of an atom?
Using an energy diagram, you can show the structure of levels and sublevels (s, p, d), on which the sulfur valence formula depends. Two differently directed arrows symbolize paired, one - unpaired electrons. The outer space of the sulfur atom is formed by orbitals of 6 particles, and 8 are necessary for stability according to the octet rule. The configuration of the valence shell is reflected by the formula 3s23p4. Electrons of the unfinished layerhave a large supply of energy, which causes an unstable state of the entire atom. To achieve stability, the sulfur atom requires two additional negative particles. They can be obtained by forming covalent bonds with other elements or by absorbing two free electrons. In this case, sulfur exhibits valency II (–). The same value can be obtained using the formula: 8 - 6=2, where 6 is the number of the group in which the element is located.
Where are compounds found in which the valence of sulfur is II (–)?
An element attracts or completely removes electrons from atoms with a lower electronegativity value on the Polling scale. Valency II (-) is manifested in sulfides of metals and non-metals. An extensive group of such compounds is found in the composition of rocks and minerals of great practical importance. These include pyrite (FeS), sphalerite (ZnS), galena (PbS) and other substances. Iron sulfide crystals have a beautiful yellowish brown color and luster. The mineral pyrite is often referred to as "fool's gold". To obtain metals from ores, they are roasted or reduced. Hydrogen sulfide H2S has the same electronic structure as water. Origin of H2S:
- is released when proteins rot (for example, a chicken egg);
- erupts with volcanic gases;
- accumulates in natural waters, oil;
- stands out in voids in the earth's crust.
Why is the formula for tetravalent sulfur oxide SO2?
The formula for dioxide shows that one sulfur atom in a molecule is bonded to two oxygen atoms, each of which needs 2 electrons to an octet. The resulting bond is covalent polar in nature (the EO of oxygen is greater). The valency of sulfur in this compound is IV (+), because the 4 electrons of the sulfur atom are shifted towards two oxygen atoms. The formula can be written as follows: S2O4, but according to the rules it must be reduced by 2. Dioxide, when dissolved in water, forms ions of weak sulfurous acid. Its s alts - sulfites - are strong reducing agents. SO2 gas serves as an intermediate in the production of sulfuric acid.
In what substances does sulfur show its highest valency?
Oxide SO3 or S2O6 is a colorless liquid that hardens at temperatures below 17°C. In the SO3 compound, the valency of oxygen is II (–), and sulfur is VI (+). The higher oxide dissolves in water and forms a strong dibasic sulfuric acid. For a large role in the production processes, the substance was called the "bread of the chemical industry." An important role in the economy and medicine belongs to acid s alts - sulfates. Calcium hydrate (gypsum), sodium (Glauber's s alt), magnesium (epsom s alt or bitter s alt) are used.
1, 2, 3, 4, 6 external electrons can participate in the formation of different types of chemical bonds. Let's name the possible valencies of sulfur, given that there are rare and unstable compounds: I (-), II (-), II (+), III (+), IV (+), VI (+). The element acquires a second positive valence inSO monoxide. The most common values II (–), IV (+), VI (+) are shown by sulfur as part of a group of substances of industrial, agricultural and medical importance. Its compounds are used in the manufacture of fireworks.
Collecting waste gases remains a big problem, including sulfur oxides IV (+), VI (+) and hydrogen sulfide, which are harmful to humans and the environment. Technologies have been created for processing these gaseous wastes and obtaining sulfuric acid and sulfates from them. For this purpose, chemical enterprises are being built next to metallurgical plants or in the same area. As a result, the volume of pollution is reduced, there is less "sulfuric acid rain".
