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 approximat... 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 1.6imes10−10m.
Step 2
Explain why magnesium is found in Group 2 and Period 3 of the Periodic Table.
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Answer
Magnesium is found in Group 2 because it has two electrons in its outer shell, which is characteristic of alkaline earth metals. Additionally, it is in Period 3 because it has three electron shells as indicated in Fig. 11.1.
Step 3
Complete the balanced symbol equation for the reaction of magnesium with oxygen.
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Answer
The balanced symbol equation is:
ightarrow 2 MgO$$
Step 4
Explain how an atom of magnesium reacts to form a magnesium ion.
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Answer
An atom of magnesium loses two electrons to form a magnesium ion (Mg²⁺). This occurs because magnesium has two electrons in its outer shell, and losing them allows it to achieve a stable electronic configuration, similar to that of neon.
Step 5
Explain why these two atoms are isotopes of magnesium.
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Answer
The two atoms are isotopes of magnesium because they have the same number of protons (12) but differ in the number of neutrons. For example, 24Mg has 12 neutrons, while 25Mg has 13 neutrons.
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
24Mg
12
12
25Mg
12
13
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