Fill in the Blanks Science Class 10 Chapter 5 Periodic Classification of Elements

Read the following statements and fill in the blanks with appropriate words:

Question.1.
Mendeleev predicted the existence of some yet to be discovered elements on the basis of ___________ in his
Periodic Table.

Question.2.
Elements in the Modern Periodic Table are arranged in __________ vertical columns called __________ and __________ horizontal rows called __________.

18, groups, 7, periods

Question.3.
In Modern Periodic Table, there are ___________ horizontal rows called _________ and ________ vertical columns called ___________.

seven, periods, eighteen, groups

Question.4.
Elements with eight electrons in their outermost energy shell are called ___________.

Noble gases

Question.5.
Anomalies in arrangement of elements based on increasing __________ mass could be removed when element discovered by Moseley.

atomic

Question.6.
If two elements have the same number of valence electrons, then they belong to the same _________ of the periodic table.

Group

Question.7.
Dobereiner grouped the elements into triads and Newlands gave the ____________.

Law of Octaves.

Question.8.
The law of triads was given by __________.

Dobereiner

Question.9.
Valency of an element is equal to the number of valence electrons which show similar _________ properties.

chemical

Question.10.
According to Modern periodic law, the elements are arranged in the periodic table in the order of their increasing _______________.

Atomic number

Question.11.
Mendeleev arranged the elements in increasing order of their __________ and according to their _________ properties.

Atomic masses, Chemical

Question.12.
___________ arranged the known elements in order of their increasing atomic weight in the form of a table called Periodic Table.

Mendeleev

Question.13.
The elements in groups, 1, 2 and 13 to 18 are known as ____________ elements.

Main group

Question.14.
The valency of an atom is equal to its _____________.

Combining capacity

Question.15.
______________ showed that group of three elements called triad had similar properties.

Dobereiner

Question.16.
The atomic size in a period _____________.

Decreases

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