The smallest unit of an element, consisting of at least one proton and (for all elements except hydrogen) one or more neutrons in a dense central nucleus, surrounded by one or more shells of electrons. In electrically neutral atoms, the number of protons equals the number of electrons.
By the time the Vesuvius eruption sputtered to an end the next day, Pompeii was buried under millions of tons of volcanic ash. About 2,000 people were dead. Some people drifted back to town in search of lost relatives or belongings, but there was not much left to find.
In 62 A.D. a violent earthquake struck the Vesuvius area. In Pompeii, the reconstruction began immediately, but it took an unusually-long time due the extent of the damage. Seventeen years later, on August 24, 79 A.D., the sudden eruption of Vesuvius buried Pompeii with ashes and lapillus. The buried city was rediscovered in the 16th Century, but it was only in 1748 that the exploration phase began, under the King of Naples Charles III of Bourbon.