NCERT Solutions Class 10 Science Chapter 5: Periodic Classification of Elements
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NCERT Solutions for Class 10 Science Chapter 5 inside Book Questions
Page Number: 81
Did Dobereiner's triads also exist in the columns of Newlands' Octaves? Compare and find out.
Yes, Dobereiner's triads also existed in Newland's classification of elements.
For Example: If we look at the second column of Newland's classification of elements, then Lithium (Li), Sodium (Na), and Potassium (K) form Dobereiner's triad.
If lithium (Li) is the first element, sodium (Na) would be the eighth element. If Potassium is the eighth element, then sodium will be regarded as the first element.
What were the limitations of Dobereiner's classification?
The limitations of Dobereiner's classification of elements were as follows:
What were the limitations of Newlands' law of octaves?
The limitations of Newlands' law of octaves were as follows:
Page Number: 85
Use Mendeleev's Periodic Table to predict the formulae for the oxides of the following elements: K, C, Al, Si, Ba
The properties of Metal Oxide are as follows:
Metal + Oxygen → Metal Oxide
The properties of Non-Metallic Oxide are as follows:
Non-Metal + Oxygen → Non-Metallic Oxide
Now, by using Mendeleev's Periodic Table, we can write the formula of the oxides of the given elements. The answer will be as follows:
Besides gallium, which other elements have since been discovered that were left by Mendeleev in his periodic table? (any two)
Apart from Gallium, the two elements discovered were Scandium and Germanium, which were the elements left by Mendeleev in his Periodic Table.
What were the criteria used by Mendeleev in creating his Periodic Table?
The criteria used by Mendeleev for creating the Periodic Table were as follows:
Why do you think the noble gases are placed in a separate group?
There are various reasons why noble gases are placed in separate groups.
NCERT Solutions for Class 10 Science Chapter 5 Inside Book Questions
Page Number: 90
How could the modern periodic table remove various anomalies of Mendeleev's periodic Table?
Modern Periodic Table removed anomalies of Mendeleev's Periodic Table in the following ways:
Name two elements you would expect to show chemical reactions similar to magnesium. What is the basis for your choice?
The chemical properties of the elements can be predicted from the electronic configuration of the elements as it shows the electron distribution of those elements.
Beryllium (Be) and Calcium (Ca) would show similar chemical reactions as magnesium.
Beryllium has an atomic number of 4 while Calcium has an atomic number of 20. Hence, if we look at the electronic configuration of these two elements, they have the same number of electrons in their outermost shell.
Magnesium Electronic Configuration - (2,8,2)
Beryllium Electronic Configuration - (2,2)
Calcium Electronic Configuration - (2,8,8,2)
So we can see that both of these elements have 2 electrons in their valence shell, so they will exhibit similar chemical properties to magnesium because it also has 2 valence electrons.
a.) Elements that have a single electron in their outermost shells are:
b.) Two elements that have two electrons in their outermost shells are:
c.) Three elements with filled outermost shells are:
In the modern periodic table, which are the metals among the first ten elements?
The first ten elements of the modern periodic table are:
From the Modern Periodic Table, the elements with 1, 2, or 3 valence shell electrons will be regarded as metals. So from the above table, we can conclude that Lithium, Beryllium, and Boron are the metals among the first 10 elements of the modern periodic table.
By considering their position in the Periodic Table, which one of the following elements would you expect to have maximum metallic characteristics?
Ga, Ge, As, Se, Be
Among the given elements Gallium (Ga), Germanium (Ge), Arsenic (As), Selenium (Se), and Beryllium (Be), Gallium is the most metallic because it lies on the leftmost side of Period 4 if compared to the above-given elements.
The electron-losing property of an element is based on its position in the modern periodic table. As we move across the table from left to right, the size of the atom decreases because of an increase in nuclear charge.
This means that the element on the leftmost side of the periodic table will have the greater atomic size with the least nuclear charge, and the elements can easily lose electrons and thus can show more metallic character. As Gallium is located to the leftmost so it has maximum metallic character.
NCERT Solutions for Class 10 Science Chapter 5 Exercise QuestionsM
Which of the following statements is not a correct statement about the trends while going from left to right across the periods of the Periodic Table?
c.) The atoms lose their electrons more easily.
Electrons losing the property of an element decrease, if we move from left to right in the periodic table. This is because the increase in nuclear charge reduces the atom's size and holds the electrons with a strong nuclear force, making it difficult for an element to lose electrons.
Element X forms a chloride with the formula XCl2, which is solid with a high melting point. X would most likely be in the same group of the periodic table as
As the question says, it forms a chloride with the formula XCl2, so element X needs to donate 2 electrons to Cl. Here only Mg is the element with 2 electrons and forms MgCl2 with chlorine.
Sodium has 1 electron in its outermost shell to form NaCl, Aluminium has 3, which will form AlCl3 and Silver has 4, which will form SiCl4.
Which element has
An atom has electronic configuration 2, 8, 7.
The positions of three elements A, B and C in the periodic table are shown below :
a.) State whether A is a metal or non-metal.
b.) State whether C is more reactive or less reactive than A.
c.) Will C be larger or smaller in size than B?
d.) Which type of ion, cation or anion, will be formed by element A?
Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the periodic table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?
The electronic Configuration of the elements is:
Because the outermost shell is closer to the nucleus and the nucleus has a stronger magnetic pull on electrons, nitrogen will be more electronegative. The electron-attracting tendency in a periodic table group decreases from top to bottom.
How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?
The basis of the modern periodic table is the atomic number, which is directly connected to the electronic configuration. So an element's group number and period number can be identified from its electronic configuration. For instance, an element would fall under group 1 or group 2 if its outermost shell had one or two electrons.
The alkali metals are all assigned to group 1 because they all have one electron in their outermost shell. As a result, the outermost shell of all group two elements has two electrons. There are 5 electrons in the outermost shell of group 15 elements. Similarly, an element's number of shells determines its period number. For instance, magnesium has an atomic number of 12, and its electronic structure is 2, 8, 2. So, it is an element of the third period.
In the Modern Periodic Table, calcium (atomic number 20) is surrounded by elements with atomic number 12, 19, 21 and 38. Which of these have physical and chemical properties resembling calcium?
The electronic configuration of elements are:
The physical and chemical characteristics of magnesium (Mg), which has an atomic number of 12, and strontium (Sr), which has an atomic number of 38, will exhibit similar chemical and physical properties as calcium, which has an atomic number of 20 because both of them have same valence electrons as calcium.
Compare and contrast the arrangement of elements in Mendeleev's Periodic Table and the Modern Periodic Table.