Fill in the Blanks Physical ScienceOnline version Questions about Physical Science. by A D 1 periodic balanced heat lens Mass is the amount of matter in an object . Weight is gravity's pull on an object . Gravity is the pull objects have on each other . The table is a chart of all the known elements . Atoms are the smallest particle of an element . Matter can't be created or destroyed . It just changes form . If you increase , particle motion increases . Protons have a positive charge . Electrons have a negative charge . A is a curved , transparent material that refracts light in a particular way . When forces are , there is no change in motion .