If an atom were to explode right in front of you, even at a distance of just 1 nanometer, it is unlikely that you would notice or feel it. The reason is that atoms are incredibly small, and their individual explosions or reactions do not generate significant macroscopic effects that can be felt or observed by our senses.
Atoms are on the scale of picometers (10^-12 meters) in size, so an explosion happening at the atomic level would involve extremely tiny amounts of matter. Additionally, the timescales of atomic processes, such as electron transitions or nuclear reactions, are typically very fast, often occurring in femtoseconds (10^-15 seconds) or shorter.
To put it into perspective, the distance of 1 nanometer is roughly the width of a few atoms, and the explosion of a single atom would involve a release of energy on an atomic scale. This energy release would likely be in the form of photons, which could include ultraviolet or X-ray radiation, depending on the specific atomic process.
However, the energy released from a single atom would be highly localized and rapidly dissipate in the surrounding environment. The amount of energy transferred to your body from such a tiny-scale explosion would be minuscule and would not produce noticeable effects.
In general, for any noticeable impact or sensation, a significant amount of matter or energy is required. Atomic-scale events, such as the explosion of a single atom, typically do not generate a sufficient magnitude of energy or mass to be perceptible to our senses.