Write a caption for your completed diagram that explains why the mass of the container increases when the steel wool is burned. Be sure to use the words: atom, compound, gas and solid in your answer.
Use the drawing tools to draw particle diagrams to show how the iron and oxygen atoms are arranged in each substance. Be sure to use different colors for each element.

At the start:
The iron is a . The atoms are packed together. They can vibrate but move about.
The oxygen is a . The particles are very . The oxygen can enter or leave the .

At the end:
The iron and oxygen have to form which is a . It contains both and iron. The together with the remaining weigh than at the start. The increases because the iron atoms are still in the solid. The reaction has added atoms to the solid. At the end of the reaction, there are atoms in the container than at the start.
What do you think? How will the mass before the fire compare to the mass after the fire?
The mass of the empty beaker is
The mass of the beaker filled with steel wool is
The mass of the beaker and contents after the reaction is
How did the mass of the beaker and its contents change?