Silver artefacts get tarnished in air due to the formation of

Silver artefacts undergo a process called tarnishing when exposed to air, which results in a characteristic black coating. This phenomenon is a form of corrosion where silver reacts with sulfur-containing compounds present in the atmosphere, most notably hydrogen sulfide (H2S) [1]. The chemical reaction between silver and these sulfur compounds leads to the formation of silver sulphide (Ag2S) [2]. While silver is relatively resistant to oxygen and does not readily form silver oxide at normal temperatures, its high affinity for sulfur makes it susceptible to tarnishing even with trace amounts of sulfur gases [3]. Although other compounds like silver chloride or silver oxide can occasionally be found in tarnish layers depending on environmental pollutants, silver sulphide is the primary and most stable compound responsible for the darkening of silver articles in typical atmospheric conditions.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > 3.5 CORROSION > p. 53
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > 1.3.1 Corrosion > p. 13
3. [3] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Activity 3.9 > p. 42