(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
(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 vale... show full transcript
Worked Solution & Example Answer:(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
How many (i) protons, (ii) neutrons, are there in an atom of potassium-39?
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Answer
In an atom of potassium-39, there are 19 protons and 20 neutrons. The atomic number of potassium is 19, which indicates the number of protons, while the mass number is 39, allowing us to calculate the number of neutrons as follows:
How are the electrons arranged in shells in this atom?
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Answer
The electrons in a potassium atom are arranged in shells according to the energy levels. The configuration for potassium is:
2 electrons in the first shell,
8 electrons in the second shell,
8 electrons in the third shell,
1 electron in the fourth shell.
Thus, it can be expressed as: 2, 8, 8, 1.
Step 3
What is the valency of potassium?
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Answer
The valency of potassium is 1. This is because potassium has one electron in its outermost shell that it can easily lose to achieve a stable electron configuration.
Step 4
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
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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The Polish-born scientist who received the Nobel Prize in 1911 for the isolation of the radioactive elements polonium and radium is Marie Curie.
Step 6
What is meant by the term half-life? What are alpha particles?
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Answer
Half-life is defined as the time taken for half of a sample of a radioactive substance to disintegrate or decay. In the case of polonium-210, this half-life is 138 days.
Alpha particles are a type of radiation consisting of helium nuclei, which are composed of 2 protons and 2 neutrons.
Step 7
Name this scientist.
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The scientist shown in the bottom picture, who discovered the nucleus of the atom, is Ernest Rutherford.
Step 8
Name the element he bombarded with alpha particles.
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Answer
The element that Rutherford bombarded with alpha particles to discover the nucleus is gold.
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