A molecule is when two or more atoms join chemically; nitrous acid is one of many molecules. Nitrous acid, which its chemical formula is HNO2, is an unstable acid and only exists in solutions or nitrite salt. Interestingly, it is naturally produced by the Earth's atmosphere, and when it reacts with water (H2O) and nitric oxide (NO), it helps regulate ozone layer in the atmosphere, which is currently being damaged by human activities. If this acid comes in contact with human, it may affect respiratory health and cause irritation, as it is slightly toxic. In this blog, it will present: 3D model of the acid composition; structure and characteristics; further information and questions; intriguing ideas and difficulties found in programming; and links to the 3D model and logo program.