chemistry
posted by Jenny .
Can someone help me to check my answer and the way I solve this problem is right or wrong?
Determine the energy required to turn a Na metal atom into a gas phase ion (Na+ (g)).
Ionization energy of Na(g) 499 kJ/mol
Electron affinity of O(g)for2e 603 kJ/mol
Energy to vaporize Na(s) 109 kJ/mol
O2(g) bond energy 499 kJ/mol
Energy change for the reaction:
2Na(s) + 1/2 O2(g)> Na2O(s) 416kJ/mol
I think I will use Na(s)>Na(g) and
Na(g)>Na+(g)
to solve this problem and this is my answer:
499+(109x2)= 717 kJ/mol
This is my answer.
Please help me out to check my answer and if I did wrong, please help me to show what steps I should do to get the right answer.
Thank you so much.

I would agree with 499 kJ/mol + 109 kJ/mol = ? but I don't know why you multiplied by 2.