To switch between mass and the number of particles, you can follow these simple steps. It gets easier once you know how!

1. Identify the substance: First, figure out what element or compound you are working with.

2. Calculate moles: Use the mass of your substance and its molar mass. Here’s the formula:

   $$\text{Moles} = \frac{\text{Mass (g)}}{\text{Molar Mass (g/mol)}}$$

3. Convert moles to particles: Next, use Avogadro's number (which is about $6.022 \times 10^{23}$ particles in one mole) to find out how many particles you have:

   $$\text{Number of Particles} = \text{Moles} \times 6.022 \times 10^{23}$$

4. Going back from particles to mass: If you start with the number of particles, first change particles into moles:

   $$\text{Moles} = \frac{\text{Number of Particles}}{6.022 \times 10^{23}}$$

5. Finally, find mass: Then, use the moles to calculate the mass like this, using the molar mass again:

   $$\text{Mass (g)} = \text{Moles} \times \text{Molar Mass (g/mol)}$$

Just remember, it's very important to keep track of your units!