Lithium, Sodium, Potassium Are All Metals that React with Water to Liberate Hydrogen Gas. is There Any Similarity in the Atoms of These Elements? - Science


Lithium, sodium, potassium are all metals that react with water to liberate hydrogen gas. Is there any similarity in the atoms of these elements?


Solution 1

Yes. The atoms of all the three elements lithium, sodium, and potassium have one electron in their outermost shells.

Solution 2

 Lithium, sodium and potassium are all metals which belong to group 1, and have 1 valence electron in their atoms. They all have the same electronic configuration. Therefore, each element shows similar chemical properties when reacting with water and liberates hydrogen gas.

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Chapter 5: Periodic Classification Of Elements - Exercise 2 [Page 304]


Lakhmir Singh Class 10 Chemistry (Science)
Chapter 5 Periodic Classification Of Elements
Exercise 2 | Q 30.2 | Page 304
NCERT Science Class 10
Chapter 5 Periodic Classification of Elements
Intext Questions | Q 4.1 | Page 90


What are the main features of Mendeleev’s periodic table?

 Name two elements that have two electrons in their outermost shells.

By considering their position in the Periodic Table, which one of the following elements would you expect to have maximum metallic characteristic?

State any three demerits of Mendeleev’s periodic table.

State whether the following statement is true of false:

According to Mendeleev's periodic law, the properties of elements are a periodic function of their atomic numbers.

State Mendeleev's periodic law.

Why is atomic number considered to be a more appropriate parameter than atomic mass for the classification of elements in a periodic table? How does the metallic character of elements vary as we move (i) from left to right in a period, and (ii) top to bottom in a group in the modern periodic table? Give reasons to justify your answers.



Write a short note.
Mendeleev’s periodic law.

Write the merits of Mendeleev’s periodic table.

Mendeleev's contributions to the concept of a periodic table laid the foundation for the Modern Periodic Table. Give reasons.

State Mendeleev's periodic law.

Use Mendeleev's Periodic Table to predict the formula of oxides of potassium, aluminum, and barium.

Why did Mendeleev's leave some gaps in his periodic table os elements? Explain your answer with an example.

Name an element whose properties were predicted on the basis of its position in Mendeleev's periodic table.

How many elements were known at the time of Mendeleev's classification of elements?

Answer the following question:

Name two elements having a single electron in their outermost shell. 

What are the demerits of Mendeleev’s periodic table?

How did Mendeleev arrange the elements in the periodic table?

How did Mendeleev's arrangement of elements correlate with the periodicity of the properties of elements?

State the contributions made by Mendeleev towards the periodic table.

Give a reason for the following:

Mendeleev's contributions to the periodic table laid the foundation for the Modern Periodic Table.

According to Mendeleev’s periodic law, properties of elements are periodic function of their _______.

At the time of Mendeleev _______ elements were known.

In Mendeleev’s periodic table eka- silicon was later named as _______.

Beryllium : alkaline earth metal : : sodium: _______

Write the molecular formula of the oxide of any one of the elements in Mendeleev’s periodic table.

Which two elements show an ambiguity regarding their sequence in Mendeleev’s periodic table?

According to Mendeleev’s periodic law properties of elements are ______.

While designing the periodic table, Mendeleev considered the chemical and physical properties of the elements.

Write scientific reason.

Mendeleev kept vacant places in the periodic table.

Write scientific reason.

There was no definitive place for isotope in Mendeleev’s periodic table.

State Mendeleev’s Periodic Law.

On which basis Mendeleev organised periodic law?

What physical and chemical properties of elements did Mendeleev consider in compiling the periodic table?

What challenges did Mendeleev face in following periodic law?

What are the limitations of Mendeleev's periodic table?

According to Mendeléev's Periodic Law, the elements were arranged in the periodic table in the order of

Which of the following statement (s) about the Modern Periodic Table are incorrect

  1. The elements in the Modern Periodic Table are arranged on the basis of their decreasing atomic number
  2. The elements in the Modern Periodic Table are arranged on the basis of their increasing atomic masses
  3. Isotopes are placed in adjoining group (s) in the Periodic Table
  4. The elements in the Modern Periodic Table are arranged on the basis of their increasing atomic number

On moving from left to right in a period in the periodic table, the size of the atom.

Properties of the elements are given below. Where would you locate the following elements in the periodic table?

  1. A soft metal stored under kerosene
  2. An element with variable (more than one) valency stored under water.
  3. An element which is tetravalent and forms the basis of organic chemistry
  4. An element which is an inert gas with atomic number 2
  5. An element whose thin oxide layer is used to make other elements corrosion resistant by the process of “ anodising”

State Mendeleev’s Law of Periodicity.

List the features of Mendeleev’s Periodic Table.

Mendeleev's periodic table was based on ______.

Name the elements whose compounds formed the basis of classification in Mendeleev's periodic table. Why did Mendeleev choose these elements?

How the formulae of these compounds had helped Mendeleev in deciding the position of an element in his periodic table?


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