Question

1. according to the reading, what force holds an atom together?

Explanation:

To determine the force holding an atom together, we recall atomic structure: protons (positive) and neutrons are in the nucleus, electrons (negative) orbit. The strong nuclear force holds protons and neutrons in the nucleus (overcoming proton - proton repulsion), and electromagnetic force (attraction between protons/neutrons and electrons) also plays a role, but the strong nuclear force is key for the nucleus, and overall, the combination of strong nuclear force (for sub - atomic particles in nucleus) and electromagnetic force (between nucleus and electrons) holds the atom. However, the primary force stabilizing the nucleus (holding protons and neutrons) is the strong nuclear force, and the electromagnetic force holds electrons to the nucleus. But in the context of "holding an atom together", the strong nuclear force binds protons and neutrons in the nucleus, and the electromagnetic force attracts electrons to the nucleus. Typically, the strong nuclear force (for the nucleus) and electromagnetic force (for electron - nucleus interaction) are involved, but the strong nuclear force is crucial for the nucleus's integrity, and together with electromagnetic, they hold the atom.

Answer:

The strong nuclear force holds protons and neutrons together in the nucleus, and the electromagnetic force (due to the attraction between the positively - charged nucleus and negatively - charged electrons) holds electrons to the nucleus. Collectively, these forces hold an atom together, with the strong nuclear force being key for the nucleus and the electromagnetic force for the electron - nucleus interaction.