Complete the following table. Atomic number Mass number Number of neutrons Number of protons Number of electrons Name of the element 9 — 10 — — — 16 — 16 — — — — 24 — — 12 Magnesium — 2 — 1 — — — 1 0 1 1 —

The atomic number is defined as the number of protons found in the nucleus of an atom. It is numerically equal to the number of electrons in it. We know that, mass number is the sum of number of protons and neutrons in an atom. That is, number of neutrons can be obtained by subtracting number of protons from the mass number. Therefore, the given table can be completed as, Atomic number Mass number Number of neutrons Number of protons Number of electrons Name of the element 9 19 10 9 9 Fluorine 16 32 16 16 16 Sulphur 12 24 12 12 12 Magnesium 1 2 2 1 1 Deuterium 1 1 0 1 1 Hydrogen

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Science Standard 9>Chapter 11 - Atomic Structure>textbook exercises>Q i

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The correct electronic configuration of potassium is

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Important Questions on Atomic Structure

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Science Standard 9>Chapter 11 - Atomic Structure>textbook exercises>Q ii

State whether true or false. If false, correct the statement.

In an atom, electrons revolve around the nucleus in fixed orbits.

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Science Standard 9>Chapter 11 - Atomic Structure>textbook exercises>Q ii

State whether true or false. If false, correct the statement.

Isotopes of an element have different atomic numbers.

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Science Standard 9>Chapter 11 - Atomic Structure>textbook exercises>Q ii

State whether true or false. If false, correct the statement.

Electrons have negligible mass and charge.

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Science Standard 9>Chapter 11 - Atomic Structure>textbook exercises>Q ii

State whether true or false. If false, correct the statement.

Smaller the size of the orbit, lower is the energy of the orbit.

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Science Standard 9>Chapter 11 - Atomic Structure>textbook exercises>Q ii

State whether true or false. If false, correct the statement.

The maximum number of electrons in $L$ shell is $10$ .

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Science Standard 9>Chapter 11 - Atomic Structure>textbook exercises>Q iii

Calcium and Argon are examples of a pair of _____.(isobars/isotones/isotopes)

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Science Standard 9>Chapter 11 - Atomic Structure>textbook exercises>Q v

Complete the following table.

Atomic number	Mass number	Number of neutrons	Number of protons	Number of electrons	Name of the element
$9$	—	$10$	—	—	—
$16$	—	$16$	—	—	—
—	$24$	—	—	$12$	Magnesium
—	$2$	—	$1$	—	—
—	$1$	$0$	$1$	$1$	—