A while back you observed the following reactions in the
lab:
–2Na
(g) + O2 (g) à 2Na2O (s)
–Zn
(s) + I2 (s) à ZnI2 (s)
–2Al
(s) + 3I2 (s) à 2AlI3 (s)
–2Al
(s) + 3Br2 (l) à 2AlBr3 (s)
–2H2 (g) + O2 (g) à 2H2O (l)
–C
(g) + O2 (g) à CO2 (g)
You learned that when a metal and a nonmetal are involved in a combination
reaction, as in the first four reactions above, the metal lose
electrons while the non-metals gain electrons.
–You
learned that metals would rather lose and non-metals gain because that
is the easier of the two option.