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 .

See also : redox reaction