The totality of all such points is space lattice. Space lattice:it is the regular arrangement of the constituent particles(atoms,ions or molecules) of a crystalline solid in three dimensional space. Lattice points or Lattice sites:They are the positions occupied by the atoms,ions or molecules in crystal lattice.he totality of all such points is space lattice. Space lattice:it is the regular arrangement of the constituent particles(atoms,ions or molecules) of a crystalline solid in three dimensional space. Lattice points or Lattice sites:They are the positions occupied by the atoms,ions or molecules in crystal lattice.