How do elements change from left to right across a period of the periodic table?

Asample of aluminum foil contains 8.60 × 1023 atoms. what is the mass of the foil?

Aglow stick contains a glass vial with chemicals. when the glow stick is bent, the vial breaks and the chemicals react to produce a glow. a science student observes that a glow stick kept in the freezer glows for a longer duration than a glow stick kept at room temperature. what conclusion can be drawn based on the observation? be sure to note the outcome and test variables in the conclusion.

How do you know when a chemical reaction has occurred