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6Li + N 2 = 2Li 3N - lithium nitride

2Li + S = Li 2S - lithium sulfide

2Li + Сl 2 = 2LiСl - lithium chloride

3Ba + N 2 = Ba 3N 2 - barium nitride
Most metals of the subgroups are covered with the oxide film when exposed to the

air. When heated in the oxygen atmosphere, all of them, with the exception of

gold, form oxides in the most stable oxidation states:

4Cr + 3O 2 = 2Cr 2O 3

2W + 3O 2 = 2WO 3

A range of standard electrode potentials
When any metal is immersed into the water, there is a potential difference at

the "metal-water" boundary which is called the electrode potential φ. The
reasons for the emerging of the electrode potential are that the polar water

molecules, while their negative poles act on the positive metal ions, transform
them into a solution. In this case the electrons remain on the metal surface,

charging it negatively.
n+
Ме + mH 2O ↔ Mе(H 2O) m + n ē.

For simplification, the hydrated water is not included in the reaction equation, and

it is written as follows:
n+
Ме ↔ Mе + n ē.

When the metal salt is added to the water, the negative charge on the surface

plate will decrease as a result of shifting the equilibrium of the electrode reaction

to the left.

With a further increase in salt concentration in the solution, there may be a

moment when the plate becomes electroneutral and even charged positively. In

this case a double electric layer with different charge marks on the plate and in the

solution is formed. There is a potential difference, which depends on the ions

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