25* C

40* C

75* C

184* C

Some of the atoms during the reaction escaped into the air.

Some of the atoms during the reaction were destroyed.

Some of the atoms during the reaction became heavier.

Some of the atoms during the reaction changed to a different kind of atom.

Several molecules of water are produced.

The mass of carbon atoms is reduced during the reaction.

The mass of the atoms in the reactant equals the mass of the atoms in the products.

The mass of hydrogen atoms is the only thing that remains the same before and after the reaction.

carbon dioxide

iron

vinegar

water

highly reactive gases, relatively non reactive metals, metalloids, very nonreactive gases, nonreactive nonmetals

highly reactive metals, relatively nonreactive metals, metalloids, reactive nonmentals, reactive gases

nonreactive gases, metalloids, nonreactive metals, highly reactive metals, highly reactive gases

nonreactive gases, nonreactive metals, highly reactive metals, metalloids, reactive nonmetals, reactive gases

The physical states of the atoms in the reactants determine the products.

Some of the atoms in the reactants will be a part of the products.

The number of atoms in the reactants determines the products.

All of the atoms in the reactants will be a part of the products.

group 1

group 2

group 16

group 18

butter melting

egg cooking

paper tearing

water evaporating

 $H\ +\ O\ \rightarrow\ H_2O$  

 $H_2\ +\ O_2\ \rightarrow\ H_2O$  

 $2H_2\ +\ O_2\ \rightarrow\ 2H_2O$  

 $H_2\ +\ O_2\ \rightarrow\ 2H_2O_2$