Question

What is the basis of modern periodic table? Why lithium with atomic number 3 and
potassium with atomic number 19 are placed in group one? What will be the atomic
numbers of the first two elements in second group?
(CBSE 2016)
M intha nolative nostinn of metals, non-metals and metalloids in group 13-​

Answer 1

Answer:the basis of modern periodic table is according to the increase in atomic number.

Lithium and Potassium are placed in group 1 as they have 1 valence electrons in their valence shell.....

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Explanation:

Answer 2

Answer:

HI...!!

THE PROPERTIES OF ELEMENTS ARE PERIODIC FUNCTION OF THEIR ATOMIC NUMBER.

ELECTRONIC CONFIGURATION OF LITHIUM IS 2,1 AND OF POTASSIUM IS 2,8,8,1 .BOTH OF THEM CONTAIN 1 ELECTRON IN THEIR OUTERMOST SHELL. SO THEIR GROUP IS 1.

ATOMIC NUMBERS OF FIRST TWO ELEMENTS IN GROUP 2 WILL BE BERYLLIUM AND MAGNESIUM BECAUSE GROUP 2 SO OUTERMOST SHELL CONTAINS 2 ELECTRONS .AND WHEN MOVING IN A GROUP NO OF SHELLS KEEPS ON INCREASING

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