Magnesium is a metal in Group 2 and Period 3 of the Periodic Table - OCR Gateway - GCSE Chemistry: Combined Science - Question 11 - 2020 - Paper 1
Question 11
Magnesium is a metal in Group 2 and Period 3 of the Periodic Table.
Fig. 11.1 shows the arrangement of electrons in an atom of magnesium.
(a) What is the approxima... show full transcript
Worked Solution & Example Answer:Magnesium is a metal in Group 2 and Period 3 of the Periodic Table - OCR Gateway - GCSE Chemistry: Combined Science - Question 11 - 2020 - Paper 1
Step 1
What is the approximate size of an atom of magnesium?
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Answer
The approximate size of an atom of magnesium is 1.6×10−10m. This value is within the range of atomic sizes for elements.
Step 2
Explain why magnesium is found in Group 2 and Period 3 of the Periodic Table.
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Answer
Magnesium is located in Group 2 because it has two electrons in its outermost shell, indicative of alkaline earth metals. It is in Period 3 as it has three electron shells.
According to Fig. 11.1, magnesium has the electron configuration of 1s² 2s² 2p⁶ 3s², which supports its classification in Period 3.
Step 3
Complete the balanced symbol equation for the reaction of magnesium with oxygen.
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Answer
The balanced equation is:
4extMg+extO2→2extMg2extO.
Step 4
Explain how an atom of magnesium reacts to form a magnesium ion.
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Answer
When magnesium reacts, it tends to lose its two outer electrons to achieve a stable electron configuration, forming a magnesium ion ( ext{Mg}^{2+}). According to Fig. 11.1, this results in a complete outer shell resembling the nearest noble gas configuration.
Step 5
Explain why these two atoms are isotopes of magnesium.
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Answer
These two atoms are isotopes because they have the same number of protons (12) but different numbers of neutrons. Isotopes of an element vary in mass due to the difference in neutron count.
Step 6
Complete the table to show the number of protons and neutrons in each isotope of magnesium.
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Answer
Isotope
Number of protons
Number of neutrons
²⁴₁₂Mg
12
12
²⁵₁₂Mg
12
13
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