H2 + O2 -> 2H2O
balanced or unbalanced pls help

Unbalanced

Explanation:

The reaction equation is given as:

             H₂  +  O₂  →   2H₂O

The given reaction flouts the law of conservation of mass and it is not balanced. To know a reaction that is balanced, the number of atoms on both sides of the expression must be the same;

                                             Number of moles

                         Reactants                                             Products

Hydrogen                2                                                            4

Oxygen                   2                                                            2

We see that the hydrogen atoms are not balanced.

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is and electronic configuration of phosphorous is .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.  

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.