Particle Balance. This element measures the mass of particles in atomic mass units. To place a particle on the balance, you can (A) click on a button in the Substance Palette and then click on the balance; (B) use the Particle Scoop; or (C) use the Select tool to move a particle onto the balance. For methods A and B, wait to click on the balance until a small black rectangle appears around the balance tray (Figure 1). For method C, wait to release the mouse button until the same rectangle appears. You can use the Select tool to removed the substance from the balance. If you delete the balance, you will delete whatever substance is on the balance.