There are things or physical objects. They can be seen, heard, smelled, tasted and touched. That is, these things can be known by the five senses.
The smallest and simplest object is the atom and not the sub-atomic particle. Sub-atomic particles are like letters of a language. While the the word ‘cat’ have a meaning (referring to the object at hand) the letters C, A and T do not have meaning as such other than identity through its system of difference. In short, ‘cat’ is like an atom and its letters are like sub-atomic particles. Atoms are stable, that is, they are meaningful. While sub-atomic particles (which are without meaning) are the building blocks of atoms, atoms (which are meaningful) are the building blocks of the larger objects.
But what constitutes an object? Certainly, atoms are objects, and things larger things built with atoms are objects. No one, I hope, will dispute that amebas, germs, bacteria, mould, ants, beetles, earth worms, mice, dogs, humans, whales, sugar, rocks, mountains, the plane Earth are objects. And, again, I hope no one will argue that a water or oxygen molecule are objects as is a body of water like the ocean or the atmosphere of a planet. As long as an object is bound by a perceived relationship we can consider it an object.
The perceived relationship is the concept, and the act of naming the concept creates communicable meaning.