CBSE Class 10 Science 2017 · Paper 31(B)/C · Question 9
Why are elements classified ? Which fundamental property of elements is used in the classification of elements in the modern periodic table ? Name and state the law based on this property. Write the number of groups and periods in this periodic table.
Answer
Elements are classified to study them systematically; atomic number is the property used; the Modern Periodic Table has 18 groups and 7 periods.
Elements are classified so that the large number of elements, and their compounds, can be studied systematically: elements with similar properties are grouped together, which makes their properties easier to study and remember and lets an element's properties be predicted from its position in the table.
The fundamental property used in the classification of elements in the Modern Periodic Table is the atomic number.
The law based on it is the Modern Periodic Law: properties of elements are a periodic function of their atomic number.
The Modern Periodic Table has 18 groups and 7 periods.
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