Kemikalija

Kemikalija is a substance with a definite chemical composition and set of properties that make it identifiable. In general usage, the term covers elements, compounds, and many pure or prepared mixtures that have a defined composition. Pure substances have fixed ratios and properties, while mixtures can vary in proportion and may be homogeneous or heterogeneous.

Substances are characterized by physical properties (state at room temperature, color, melting and boiling points, density) and chemical properties (reactivity, acidity or basicity, toxicity, flammability). They participate in chemical reactions to form new substances, often with measurable energy changes.

Common categories include elements (basic building blocks that cannot be broken down by chemical means), compounds (substances formed from two or more elements in fixed ratios), and mixtures (combinations of substances without new chemical bonds).

Chemicals are essential in science, industry and daily life: medicines, fertilizers, solvents, fuels, cleaning agents, plastics, and many household products. Examples include water (H2O), salt (NaCl), and ethanol (C2H5OH).

Safety and regulation: many chemicals pose risks to health or the environment. Handling, storage, labeling, and disposal require care. Information often appears on safety data sheets and hazard labels, and regulatory frameworks govern production, transport, and use to reduce risk (for example, hazard communication and labeling schemes and regional chemical regulations).

Environmental and ethical considerations include minimizing exposure, avoiding unnecessary synthesis, and choosing safer substitutes when possible.