Learn Online study

Just another WordPress site

1. Home
2. /
3. Basic study
4. /
5. Periodic Classification of Elements Questions and Answers of the Lesson-

# Periodic Classification of Elements Questions and Answers of the Lesson-

1-What are the limitations of Newland’s octet theory?

The principle of Newland’s octet was applicable only to calcium, because every eighth element in Newland’s octet after calcium did not or had properties similar to that of the first element.

Newland placed cobalt (Co) and nickel (Ni) in a group on the basis of similar properties, while iron [आयरन (Iron) Fe] The properties of which are similar to those of cobalt (Co) and nickel (Ni), were kept at a great distance from these two elements.

2-Which criteria did Mendeleev adopt to prepare his periodic table?

Mendeleev arranged the elements in a table in ascending order of their atomic mass, starting with hydrogen (H).

Mendeleev selected the compounds formed by reacting with oxygen and hydrogen of elements under chemical properties, because most of the elements combine with hydrogen and oxygen to form compounds. Mendeleev considered the formulas of hydrides and oxides of elements as fundamental properties in the classification of elements.

3- Why do you think noble gases were placed in a separate group?

Noble gases are also called inert gases. Since inert gases also do not react with hydrogen and oxygen, noble gases were placed in a separate group, considering the ability to react as a basic property.

Why were the noble gases placed in a separate group?

Noble gases were not discovered during Mendeleev’s time. These are inert gases and are found in very small quantities, so their discovery took a long time. Noble gases are inert, so it is easily possible to place them in a separate group. This did not even tamper with the original design of Mendeleev’s periodic table.

Write the names of any two elements that have chemical reactions similar to magnesium. On what basis did you choose these elements?

Answer: The chemical reaction of beryllium and calcium is similar to that of magnesium, because:

These elements have the same number of valence electrons (2). This means they all give up 2 electrons to form a compound.
All of them fall in Group 2.

6-Lithium, sodium and potassium; These are all metals that react with water to form hydrogen gas. What do the atoms of these elements have in common?

Answer: Lithium, sodium and potassium have one electron each in their outermost orbitals. This means that they can easily form ionic bonds with any other element by sacrificing 1 electron. Therefore, they are highly electropositive and reactive metals.

7-Helium is an inert gas and neon shows very little reactivity. What do these two atoms have in common?

Answer: The outer orbits of helium and neon are completely filled. Therefore these elements are stable and inert.

### 1-lithium, sodium and potassium; These are all metals that react with water to form hydrogen gas. What do the atoms of these elements have in common?

Lithium, sodium and potassium have one electron each in their outermost orbitals. This means that they can easily form ionic bonds with any other element by sacrificing 1 electron. Therefore, they are highly electropositive and reactive metals.

### 2-Why do you think noble gases were placed in a separate group?

Noble gases are also called inert gases. Since inert gases also do not react with hydrogen and oxygen, noble gases were placed in a separate group, considering the ability to react as a basic property.