Can anyone tell me why potassium is monovalent

To put it simply. Elements have different electron shells, each layer has 1 8 (or 1 18) electrons, the outermost electrons are different according to the gravitational pull of the nucleus, the outer electrons are less than 4, they are easy to lose electrons, they become stable, k na is easy to lose if there is 1 in the outermost shell. Other elements can lose electrons or gain electrons or make the outer electrons semi-full and stable, and then have different valencies.

When various elements make up a compound, the ratio of their atomic numbers is constant. For example, a water molecule is composed of one oxygen atom and two hydrogen atoms, which means that one oxygen atom has the ability to bind two hydrogen atoms. In order to describe this particular proportional relationship, to illustrate the ability of each element to bind to other atoms, and thus to the elemental ratio of a compound, people have given each element a numerical value with a plus or minus sign - valency.

This is convenient and effective, because usually the binding capacity of the element is fixed, for example, the oxygen atom can bind two hydrogen atoms with +1 valence, and when it combines AG with the same +1 valence, it also binds two.

In practical application, oxygen is specified as -2 valence and hydrogen is +1 valence, and then the valency of other elements is determined by the ratio of hydrogen and oxygen to other element compounds. For example, the chemical formula of MGO states that magnesium is +2 valence, and the chemical formula of H2S states that S is -2 valence, in short, the algebraic sum of valency is zero.

Although the bonding ability of elements is generally stable and the valency is fixed, the valence phenomenon is still very common. Generally, metals are less variable, but non-metals tend to be polyvalent because their binding capacity is variable.

Valency is actually the number of electrons that an atom gains or loses. When an atom gains an electron, it manifests a valence of -1, and loses an electron to gain a valence of +1.

According to the principle of entropy increase, some parts of nature are moving towards stability, and atoms are no exception. For an atom to reach a stable state, the number of electrons in its outermost shell must be 8 (or 2 if there is only one layer). The outermost electron configuration of potassium is 2 8 8 1 The loss of one of the outermost electrons is stable, that is, the loss of one electron, that is, the -1 valence.

For related content, please refer to Poly (Pauli) incompatibility principle, Hunt principle, and energy level interlacing principle.

You should know the structure of the atom, each electron shell has its own maximum number of electrons that can be accommodated, for the sake of convenience, it is recorded as a (a can change with the different electron shells), when the number of electrons in the outermost shell is less than a 2, it is easy to lose electrons and become a cation, but the loss of the most can only lose all the outermost shells (only the main group of metals, because you are talking about potassium, the others are 54 off. It happens that the outermost shell of potassium is 1 electron, so it is +1 valence, and you can also look at other things such as calcium, magnesium, etc., which also conform to this property.

Because potassium has only one electron that is easily lost.

If you are a middle and high school student, you just need to know this knowledge point, and the deeper knowledge can be understood in college.

The valency of potassium is +1 valence. The outermost electron number of potassium is 1, and after losing this electron, it has a positive charge of 1 unit, and the valency is +1, when potassium is elemental, the valency of the element is 0There is no other valence state.

Potassium is a silvery-white, soft metal, waxy, cut with a knife, with a low melting boiling point, less dense than water, and extremely chemically reactive (more reactive than sodium). It is one of the elements of group A and belongs to alkali metals.

The role of potassiumPotassium is not a component of organic compounds in plants, mainly in an ionic state in plant cell fluid, it is an activator of a variety of enzymes, plays an important role in the metabolic process, not only to promote photosynthesis, but also to promote nitrogen metabolism, improve plant nitrogen absorption and utilization.

Potassium regulates the osmotic pressure of cells, regulates plant growth and economical water use, and enhances the plant's ability to resist adverse factors (drought, cold, disease, salinity, lodging). Potassium can also improve the quality of agricultural products.

The above content refers to Encyclopedia-Potassium.