What are the two conditions for a substance to contain the same group of atoms?

Same cluster of atoms.

Two conditions must be met:

1) The type and number of atoms that make up the atomic cluster are the same;

2) Valency of each element.

Same. Constitutes permanganate ions.

Although the atomic types and numbers of mno4- and manganese ion mno4 2- are the same, the manganese element in the permanganate ion is +7 valence, and the manganese element in the manganate ion is +6 valence, and the valence of manganese element is different, so they belong to different atomic groups.

To know the atomic group to pay attention to:

1) An atomic cluster is a part of a molecule. In compounds composed of three or more elements, the molecules often contain some kind of atomic cluster.

2) The cluster of atoms does not remain the same in any chemical reaction. In some chemical reactions, the atomic clusters change, such as the chlorate in potassium chlorate.

3) Clusters of atoms are often referred to as "roots" or "root ions". When writing the atomic cluster symbol, the charge it carries should be indicated, such as: CLO3-, SO42-, OH-, NH4+, etc., and do not take the atomic cluster symbol as a chemical formula, such as mistaking sulfate (SO42-) for sulfur tetroxide.

The atomic group mno42- in kmno4- and the atomic group mno42- in k2mno4- are different atomic groups. The former is called permanganate, and the latter is called manganate.

NopeAtomic clustersThe substance is KClPotassium chloride

KCL is composed of potassium and chloride ions and does not contain atomic clusters.

Potassium chloride is an inorganic compound.

The chemical formula is KCL, and the appearance is like table salt, which is odorless and salty. It is often used for low-sodium salts.

Mineral water additives. Potassium chloride is a commonly used electrolyte balance regulator in clinical practice, with definite clinical efficacy, and is widely used in various clinical departments.

**Content. This product is calculated as a dry product, and the state content of potassium chloride (KCL) shall not be less than.

Characters. This product is colorless long prismatic, cubic crystalline or white crystalline powder mold track; Odorless, salty and astringent in taste.

This product is soluble in water, in denier ethanol.

or insoluble in ether.

Differential. The aqueous solution of this product shows potassium salt and chloride.

(Appendix to Part II of the 2010 edition of the Pharmacopoeia).

The above content reference: Encyclopedia - potassium chloride.

The same atomic group must meet two conditions:

1) The type and number of atoms that make up the atomic cluster are the same;

2) The valency of each element in the fracture section is the same.

Although the types and numbers of atoms constituting the permanganate ion mno4- and the manganese ion mno4 2- are the same, the manganese element in the permanganate ion is +7 valence, the manganese element in the manganate ion is +6 valence, and the valence of manganese element is different, so they belong to different atomic groups.

According to its definition, the mean difference in A is one CH2, and the mean difference in B is one CH2, but C is C2H5Cl, C2H4Cl2, and C3H3Cl3 respectively, and the composition is not the same atomic cluster.

However, this is your definition in this question, and the homolog we generally learn refers to "substances with similar structures and poor composition of CH2". Burning years, such as ethylene, propylene, and butylene, can be said to be. However, methanol, ethylene glycol, and glycerol are not homologues by the correct definition.

But the stem of this question redefines the homologue, that is, it is necessary to do it according to the information skin of this question.

The atomic cluster in ckmno4 is mno4 - the atomic cluster in k2mno4 is mno4 2-

Select B. Because the same atomic cluster must first carry the same tung or charge laughing ruler.

Although the valency of S is different in B, both SO3 2- and SO4 2- are -2 valent. The valency of mno4- and mno42- is obviously different.

a All contain NH4+

Charged atomic clusters are also called roots or groups, such as hydroxide OH-, nitrate NO3-, carbonate CO3-, sulfate SO4-, chlorate CLO3-, phosphate PO43-, bicarbonate HCO3-, ammonium NH4+, etc. It is worth noting that atomic clusters cannot exist independently, but are only a component of a compound.

In solution, the atomic clusters participate in the reaction as a whole. Various atomic clusters have their own characteristic reactions, such as CO3- turning into CO2 when it meets acid, SO42- when it meets Ba2+ to produce a white precipitate insoluble in dilute nitric acid, and OH- makes the phenolphthalein test solution turn red. The presence of roots can be tested using characteristic reactions.

Note to distinguish between manganate MNO42- and permanganate MNO4-, both of which have the same composition, but the valency of manganese is different, so the root price is different, manganese in manganate is +6 valence, and manganese in permanganate is +7 valence. There are also metaphosphate PO3- and phosphite PO33-, where the former has a phosphorus of +5 valence and the latter phosphorus of which is of +3 valence. The valency of the atomic cluster is equal to the algebraic sum of the valencies of the elements in the root.

choose a, and [because both compounds have ammonium (NH4) atomic clusters; contains ammonium and bicarbonate; contains ammonium and nitrate; contains permanganate; Contains manganate. In many chemical reactions, groups of atoms that participate in the reaction as a whole are called clusters. 】

a Contains the same atomic group NH4+

In many chemical reactions, as a whole participate in the reaction, such a group of atoms is called an atomic group, and the atom group has the following characteristics:

1. Contains the same atoms.

2. The number of atoms is the same.

3. The valency of each atom is the same.

For example, the atomic cluster of KMNO4 is MNO4(-1), where MN is the positive 7-valent, and the K2MKo4 cluster is MNO4(-2), where MN is the positive 6-valence, so their atomic clusters are not the same.

The atomic clusters in KMNO4 and K2MMO4 are different:

The former has a valency of +7 valence for mno4- in the middle.

The valency of Mn in the latter mno4 2- is +6 valence.

The composition of the two atomic clusters above is the same, but the valency of the mn element is different, so they are different atomic clusters.

You look at the reaction of 2NO2 N2O4.

The composition of N2O4 consists of 2—No2 atomic clusters.

The valency of each element is the same, and the composition cannot be regarded as the same, after all, N2O4 can be regarded as a dimer.

Both must be the same to count.