How to learn valence and how to calculate valence

potassium, sodium, hydrogen and silver are monovalent, calcium, magnesium, zinc, barium are bivalent;

Chlorochlorobromoiodine is negative monovalent, usually oxygen is negative bivalent;

Copper is one and two aluminum, and iron has two and three;

Carbon has positive two and positive four, and sulfur has negative two positive four and positive six.

To calculate the valency of an atom, we must first know what valence states the atom has, and then calculate it according to the sum of the valence is equal to zero.

Valence tables of common elements and atomic clusters.

Potassium k + 1 chlorine c1-1, +1, +5, +7

Sodium Na + 1 oxygen O-2

Silver ag +1 sulfur s-2, +4, +6

Calcium, Ca+2, C+2, +4

Magnesium mg + 2 silicon si + 4

Barium BE+2 nitrogen n-3, +2, +4, +5

Zinc Zn + 2 phosphorus p-3, +3, +5

Copper Cu +1, +2 sulfate SO42--2

Iron Fe + 2, +3, carbonate CO32--2

Aluminum Al+3 nitrate NO3--1

Manganese: Mn+2, +4, +6, +7, hydroxide, oh--1, hydrogen h+1, ammonium, NH4++1

Fluorine F-1 phosphate PO43--3

For example, Fe2O3 must have a valence of -2 for oxygen, so iron is +3 valence. In Fe3O4, oxygen is -2 valence, so the total valence state of the three iron is +8 valence, while iron has two valence states, +2 and +3, so that there are two moles of ferric tetroxide and one mole of ferric tetroxide.

It is calculated according to the sum of valencies equal to zero, and it is necessary to know the valency of common elements.

This has to be memorized, the teacher taught the mantra, I looked it up on the Internet, and it is the same as the divination taught by the teacher.

This is what I looked up online.

Valency of common substances.

Monovalent potassium, sodium and hydrogen silver, bivalent calcium, magnesium, barium, zinc, oxygen.

12 copper, 2 triiron, 3 aluminum, 4 silicon, 5 valent phosphorus.

Ditetracarbon, 246 sulfur.

Fluoroaluminum bromide, minus one elemental zero.

Atomic agglomeration valency.

Negative hydroxide mononitrate, negative disulfate carbonate.

There is also negative trivalent phosphoric acid, and only ammonium root is positive monovalent.

These are what our teachers teach.

Hope you can help.

Whoever is found is x, and the others are known, and the valency of each element is multiplied by the algebraic sum of their atoms in a molecule to zero, and x can be found, but it must be marked with positive and negative.

The highest positive price is the number of outermost electrons, and the lowest negative price is the highest positive price minus 8 and the only negative price.

It is calculated according to the algebraic sum of the valency of each element in the compound as zero.

Valency formula:

Monovalent potassium, sodium, silver chloride, it is not difficult to talk about valence, divalent oxygen, calcium, barium, magnesium, zinc, di-triiron, di-tetracarbon, Suishi, trialuminum, tetrasilicon, pentavalent phosphorus, minus 246 sulfur is complete, and the unit valence state is zero. Copper-mercury bivalent is the most common.

Atomic clusters, remember six, minus one nitrate hydroxide, minus disulfate carbonate, minus three remember phosphate, positive monovalent is ammonium.

These are commonly used, just memorize them)

Another: the formula for calculating the valence (below, usually set up) 1 Write the symbols of the two elements that make up the compound, the positive valence is written on the left, and the negative valence is written on the right.

p o2 finds the least common multiple of the absolute value of the positive and negative valence of the two elements, 5 2 = 103 finds the atomic number of each element, the least common multiple positive number (or negative valence number) = atomic number.

p:10/5=2 o:10/2=5

4. Write the atomic number at the bottom right of the symbol of each element to obtain the chemical formula:

p2o55 checks the chemical formula, and the chemical formula is correct when the algebraic sum of the total positive and negative valences is equal to 0. （5）×2+（-2）×5=+10-10=0

Answer: The chemical formula of this phosphorus compound is P2O5

The valency of o is -2