Dioksidi

Dioksidi, or dioxides, are a broad class of inorganic compounds composed of two oxygen atoms bonded to a central element. Their general formula is XO2. They include simple molecular species such as carbon dioxide (CO2) and nitrogen dioxide (NO2), as well as extended oxide networks such as silicon dioxide (SiO2) and titanium dioxide (TiO2).

Most dioksidi arise from oxidation of elements or from dehydration of higher oxides. The structures vary: CO2 is a linear, nonpolar molecule; NO2 is a bent, reactive radical; TiO2 and SiO2 form three-dimensional solid networks. The oxidation state of the central element is commonly +4 in many XO2 compounds, though exceptions exist.

Chemical behavior is dominated by their oxide character. They are typically acidic oxides that react with water to form acids (for example CO2 + H2O → H2CO3). They can form salts with bases, such as carbonates and sulfites. Some dioksidi, notably NO2 and SO2, are gases at room temperature and act as pollutants, while others are solid materials used in pigments, catalysis, or as glass-forming constituents.

Industrial and natural relevance: atmospheric CO2 is a major greenhouse gas; SiO2 is the main component of sand, quartz, and glass; TiO2 is a widely used white pigment and photocatalyst. Dioksidi are also important in environmental science due to their roles in air quality, acid rain formation, and climate cycles.

Safety: Many dioksidi are hazardous in high concentrations. Exposure to NO2 and SO2 can irritate the respiratory system; long-term emissions contribute to acid deposition and ecological effects. Handling and emissions are regulated to limit environmental and health impacts.