Atoms of the same element having same atomic number but different mass number are called isotopes. Since the atomic number of all the isotopes of a given element is same, the number of electrons present in them is also the same. Because of the same number of electrons, their electronic configuration and hence the chemical properties of the isotopes are also the same.

S. Chand's ICSE CHEMISTRY Book -1 CLASS- 9>Chapter 4 - Atomic Structure>Questions>Q 9

EASY

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IMPORTANT

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${}_{12}^{24}{Mg}$ and ${}_{12}^{26}{Mg}$ are symbols of two isotopes of magnesium.
Give reasons why the two isotopes of magnesium have different mass numbers.

Important Questions on Atomic Structure

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IMPORTANT

S. Chand's ICSE CHEMISTRY Book -1 CLASS- 9>Chapter 4 - Atomic Structure>Questions>Q 10

Sulphur has an atomic number of

16

and a mass number of

32

. State the number of protons and neutrons present in the nucleus of sulphur. Draw a simple diagram to show the arrangement of the electrons in an atom of sulphur.

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IMPORTANT

S. Chand's ICSE CHEMISTRY Book -1 CLASS- 9>Chapter 4 - Atomic Structure>Questions>Q 11

Elements $X, Y$ and $Z$ have atomic numbers $6, 9$ and $12$ respectively. Which of the above elements will:

(a) forms anion or negative ion.

(b) forms cation or positive ion.

(c) has $4$ electrons in the outermost orbit.

HARD

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IMPORTANT

S. Chand's ICSE CHEMISTRY Book -1 CLASS- 9>Chapter 4 - Atomic Structure>Questions>Q 12

According to Dalton’s Atomic Theory, atoms of the same element are identical in all aspects. But according to the Modern Atomic theory, this postulate is proved wrong. Explain.

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S. Chand's ICSE CHEMISTRY Book -1 CLASS- 9>Chapter 4 - Atomic Structure>Questions>Q 13

What is the relation between the number of protons and the number of electrons in an atom?

EASY

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IMPORTANT

S. Chand's ICSE CHEMISTRY Book -1 CLASS- 9>Chapter 4 - Atomic Structure>Questions>Q 14

How do metals differ from non-metals in ion formation.

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