Base metals

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H Hey
Li Be B. C. N O F. No
N / A Mg Al Si P S. Cl Ar
K Approx Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mon Tc Ru Rh Pd Ag CD In Sn Sb Te I. Xe
Cs Ba * Hf Ta W. re Os Ir Pt Au Ed Tl Pb Bi Po At Marg
Fr. Ra ** Rf Db Sg Bra Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Above
* La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho He Tm Yb Lu
** Ac Th Pa U Np Pooh At the Cm Bk Cf It Fm Md No Lr

Base metals are metals whose redox pairs have a negative standard potential (with respect to the normal hydrogen electrode ). Metals with a positive standard potential, on the other hand, are called precious metals .

Under normal conditions, base metals react with oxygen from the air , they oxidize . While iron , for example, rusts through , zinc and aluminum , for example , passivate (protect) each other by forming a corrosion-resistant oxide layer that prevents further oxidation. Passivated metals often appear noble, but are not because they would in principle oxidize further if the oxide layer did not prevent contact with oxidizing agents (e.g. oxygen). They are inert , but not thermodynamically stable .

Some metals also react with a positive standard potential, since oxygen has a strong positive standard potential. Such metals are called semi-precious metals .