Leaving Cert Chemistry Atomic Structure: 5. (a) (i) How many (i) protons

5. (a) (i) How many (i) protons, (ii) neutrons, are there in an atom of potassium-39? (ii) How are the electrons arranged in shells in this atom? (iii) What is the valency of potassium? (b) In November 2006, a former Soviet agent, Alexander Litvinenko, died in London - Leaving Cert Chemistry - Question 5 - 2007

Question 5

5.-(a)-(i)-How-many-(i)-protons,-(ii)-neutrons,-are-there-in-an-atom-of-potassium-39?-(ii)-How-are-the-electrons-arranged-in-shells-in-this-atom?-(iii)-What-is-the-valency-of-potassium?--(b)-In-November-2006,-a-former-Soviet-agent,-Alexander-Litvinenko,-died-in-London-Leaving Cert Chemistry-Question 5-2007.png

5. (a) (i) How many (i) protons, (ii) neutrons, are there in an atom of potassium-39? (ii) How are the electrons arranged in shells in this atom? (iii) What is the ... show full transcript

Worked Solution & Example Answer:5. (a) (i) How many (i) protons, (ii) neutrons, are there in an atom of potassium-39? (ii) How are the electrons arranged in shells in this atom? (iii) What is the valency of potassium? (b) In November 2006, a former Soviet agent, Alexander Litvinenko, died in London - Leaving Cert Chemistry - Question 5 - 2007

Step 1

(i) How many (i) protons, (ii) neutrons, are there in an atom of potassium-39?

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Answer

An atom of potassium-39 has:

Protons: 19 (this is the atomic number of potassium).
Neutrons: To find the number of neutrons, subtract the atomic number from the mass number:

$ext{Neutrons} = ext{Mass Number} - ext{Atomic Number} = 39 - 19 = 20$

Step 2

(ii) How are the electrons arranged in shells in this atom?

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Answer

The electron arrangement for a potassium atom (atomic number 19) is as follows:

First Shell: 2 electrons
Second Shell: 8 electrons
Third Shell: 8 electrons
Fourth Shell: 1 electron

Thus, the electronic configuration is 2, 8, 8, 1.

Step 3

(iii) What is the valency of potassium?

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Answer

The valency of potassium is 1. This means potassium can lose one electron to achieve a stable electronic configuration.

Step 4

(i) Name the French scientist who discovered radioactivity in 1896.

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Answer

The French scientist who discovered radioactivity in 1896 is Henri Becquerel.

Step 5

(ii) Name the Polish born scientist who received the Nobel prize in 1911 for the isolation of the radioactive elements polonium and radium.

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Answer

The Polish born scientist is Marie Curie.

Step 6

(iii) What is meant by the term half-life? What are alpha particles?

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Answer

The term half-life refers to the time taken for half of a sample of a radioactive substance to disintegrate or decay.

Alpha particles are helium nuclei, composed of two protons and two neutrons, emitted during radioactive decay.

Step 7

(i) Name this scientist.

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Answer

The scientist who discovered the nucleus of the atom is Ernest Rutherford.

Step 8

(ii) Name the element he bombarded with alpha particles.

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Answer

The element he bombarded with alpha particles is Gold.

(i) How many (i) protons, (ii) neutrons, are there in an atom of potassium-39?

(ii) How are the electrons arranged in shells in this atom?

(iii) What is the valency of potassium?

(i) Name the French scientist who discovered radioactivity in 1896.

(ii) Name the Polish born scientist who received the Nobel prize in 1911 for the isolation of the radioactive elements polonium and radium.

(iii) What is meant by the term half-life? What are alpha particles?

(i) Name this scientist.

(ii) Name the element he bombarded with alpha particles.

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