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9 (a) An aluminum atom has the atomic number 13 and the mass number 27 - Edexcel - GCSE Chemistry - Question 9 - 2019 - Paper 1
Question 9
9 (a) An aluminum atom has the atomic number 13 and the mass number 27. Which row shows the numbers of subatomic particles present in an aluminium ion, Al$^{3+}$? (... show full transcript
Worked Solution & Example Answer:9 (a) An aluminum atom has the atomic number 13 and the mass number 27 - Edexcel - GCSE Chemistry - Question 9 - 2019 - Paper 1
Step 1
(a) Which row shows the numbers of subatomic particles present in an aluminium ion, Al$^{3+}$?
Answer
An aluminum ion, Al, has an atomic number of 13, which means it has 13 protons. The mass number is 27, which represents the total number of protons and neutrons. To find the number of neutrons, we can subtract the number of protons from the mass number:
Number of neutrons = Mass number - Number of protons = 27 - 13 = 14.
Since it is an ion with a +3 charge, it has lost 3 electrons, resulting in 10 electrons (13 - 3). Thus, the correct row is:
Protons: 13 | Neutrons: 14 | Electrons: 10.
Step 2
(b) Starting with 1.35g of magnesium, calculate the maximum mass of magnesium oxide that could be formed in this reaction.
Answer
To calculate the maximum mass of magnesium oxide (MgO) that can be formed:
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Calculate moles of magnesium (Mg):
Molar mass of magnesium = 24.0 g/mol
Number of moles of magnesium =
ext{moles} = rac{ ext{mass}}{ ext{molar mass}} = rac{1.35 ext{g}}{24.0 ext{g/mol}} = 0.05625 ext{ mol}
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Use the balanced equation:
According to the equation, 2 moles of Mg produce 2 moles of MgO. Therefore, 0.05625 moles of Mg will produce the same amount of MgO:
ightarrow 0.05625 ext{ mol MgO}$$
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Calculate the maximum mass of MgO formed:
Molar mass of MgO = 24.0 (Mg) + 16.0 (O) = 40.0 g/mol
Mass of MgO = moles × molar mass =
Thus, the maximum mass of magnesium oxide that could be formed is 2.25 g.
Step 3
Step 4
(d) Explain how sodium and chlorine atoms form the ions in sodium chloride and how the ions are arranged in the solid sodium chloride.
Answer
Sodium (Na) has the electronic configuration of 2.8.1, indicating it has one electron in its outer shell. Chlorine (Cl), on the other hand, has a configuration of 2.8.7, meaning it needs one more electron to complete its outer shell.
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Formation of Ions:
- Sodium loses its one valence electron to achieve a stable electronic configuration like neon, becoming a sodium ion (Na) with a +1 charge.
- Chlorine gains this electron to complete its outer shell, becoming a chloride ion (Cl) with a -1 charge.
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Ionic Bonding:
- The oppositely charged ions (Na and Cl) attract each other due to electrostatic forces, forming ionic bonds.
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Arrangement in Solid Sodium Chloride:
- In solid sodium chloride, the ions are arranged in a crystal lattice structure, maximizing the attractive interactions between the Na and Cl ions and minimizing repulsive forces. Each sodium ion is surrounded by six chloride ions, and vice versa, which gives the solid its characteristic properties.