How can you tell that the beryllium atom is unstable?

Answer 1

You can tell that the beryllium atom is unstable because beryllium only has 2 valence electrons in its outer shell. An atom becomes stable when it has eight valence electrons, so in the case of beryllium it would have to lose those 2 electrons in its outer shell to become stable. often forming a cation with a 2+ charge.

Answer 2

One indication of beryllium atom instability is its tendency to form compounds readily. Beryllium atoms will often react with other elements to achieve a stable electron configuration. Additionally, beryllium isotopes may undergo radioactive decay due to their unstable nucleus.