The third year of junior high school! Chemical valency problem Derive the chemical formula of a comp

You are talking about the valency of two elements that are known, how to write the chemical formula, right?

The valency should be memorized, and then the chemical formula should be written with the valency. Here's how to write the chemical formula with the cross method:

For example, potassium oxide: 1. Write the element symbols in order. Generally, the positive price comes first, and the negative price comes last.

2. Mark the valency of the element above the symbol of the element.

3. Cross the absolute value of the valency of the element and write it in the lower right corner of another element as the number of atoms of the element (the concession fraction that can be reduced), 4. Omit the valency as the chemical formula.

For example: potassium oxide --- ko---k o---k2o

Calcium oxide---cao---ca2o2---cao

If the valence is well remembered, there is no need to standardize the valence, and the chemical formula can be written directly according to this method, which is fast and accurate.

For example: potassium oxide --- ko---k2o (potassium is +1 valence cross in the lower right corner of o, the number is 1 omitted and not written.) Oxygen is -2 valence and 2 is directly crossed in the lower right corner of k to get the chemical formula. ）

Another example: copper oxide --- cuo (copper + 2 valence oxygen-2 valence, can be divisible by 2, the number is 1 omitted and not written,) In this case, you can directly write the chemical formula cuo

For example, alumina ---AIO---AI2O3 (the valency is not written on paper, it is used directly in the heart).

If we encounter three elements, how do we write their chemical formulas? This involves the valency of the atomic group, and the root formula and valency of the atomic group are memorized, and then the chemical formula can also be written using the cross method. Note: When writing, it is enough to treat the cluster as an atom.

For example: sodium sulfate --- Na+1 valence, sulfate SO4(-2) valence, so the chemical formula is: Na2SO4

Calcium nitrate---Ca(NO3)--Ca(NO3)2. If there are more than two atomic clusters, they should be enclosed in parentheses.

In this way, the chemical formula of many compounds can be written, and the valency can be memorized according to the formula, including the valency of the atomic cluster.

If it is not an atomic group, it is not required in junior high school.

If you write the chemical formula with valency, you can only write with atomic clusters in junior high school if you have more than 3 elements.

Some valencies are required to be memorized, as long as they are memorized and inferred, which is how I came in the third year of junior high school.

1) Fexo3, please calculate the value of x, and write the chemical formula:

2) Cu2(OH)2CO3, where the valency of Cu is found.

Chemically, the valency is used to express the number of element atoms that are combined with each other, and the valency of the lead element in the element is 0(3) The basis for applying valency to derive the chemical wheel of matter is that this compound does exist.

When anions and cations interact to form a compound, the entire compound becomes (invisible) electrical.

The four meanings of H2O : 1, water 2, water is composed of two elements, hydrogen and oxygen 3, 1 water molecule 4, 1 water molecule is made up of 2 hydrogen atoms and 1 oxygen atom.

Write out the meaning of the representation: h hydrogen element or 1 hydrogen atom.

H2: Hydrogen, hydrogen molecule.

2h: 2 hydrogen atoms.

2h2: 2 hydrogen molecules.

Valency formula: Monovalent ammonium, hydroxide, plus a nitrate. Divalent sulfuric acid, carbonate, and trivalent phosphate are all negative except for ammonium.

Oxygen usually shows -2 valence, hydrogen usually shows +1 valence, and when metal elements are combined with non-metallic elements, metal elements show positive valence, and non-metallic elements show negative valence. Some elements will show different valencies in unused substances, and the same element may exhibit different valencies in the same substance, such as ammonium nitrate.

In a compound, the algebraic sum of positive and negative valencies is 0

It is known that oxygen is -2 valence, and the valency of sulfur in sulfur dioxide is +4 The mass ratio of carbon and oxygen in carbon dioxide is equal to 3:8 The valence of carbon monoxide is: c+2 o -2

The valency of nitric acid is: Hno3 H: +1 N: +5 O:-2 The valency of nitrogen dioxide is: No2 N: +4 O:-2 The valency of ammonia is: NH3 N: -3 H: +1

Not visible One hydrogen atom Hydrogen Two hydrogen atoms Two hydrogen molecules Ammonium nitric acid Hydroxide Carbonate Sulfuric acid Ammonium phosphate.

2 1 Positive and negative can be nitrogen in ammonium nitrate.

Zero 4 12:32 3:8

c is 2 nitride valency in nitric acid is 5

Nitrogen dioxide in nitrogen dioxide is 4

The valency of nitrogen in ammonia is 3

1. In general, h is +1 and o is.

2 valence. 2. The valency of simple ions can memorize the valency formula.

3. Atomic clusters.

The structure is remembered as a whole. Like oh

Display. 1 price;

SO42 - Yes -

2 valence. 4. The valency of an atom with valence is often found by the sum of valency algebra in the compound equal to 0.

For example, kiO3, O is generally -2 valence, and K is +1 valence. So set.

If the valence state of i is a, then there is: (-2)*31+a

a=+55, the valency must not be contrary to the structure (the valency should be related to the structure of a certain atom). h2o2nah, etc.

1.2.

where x1 refers to how much chlorine is contained in 135kg of chlorine dioxide.

x2 refers to how many kg 84 is needed

Calculate x2.