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2 (a) An aluminium atom has the atomic number 13 and the mass number 27 - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2019 - Paper 1

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2 (a) An aluminium 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:2 (a) An aluminium atom has the atomic number 13 and the mass number 27 - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2019 - Paper 1

Step 1

an aluminium atom has the atomic number 13 and the mass number 27

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Answer

The atomic number indicates the number of protons, which is 13. The mass number is the sum of protons and neutrons. Therefore, the number of neutrons can be calculated as follows:

Number of neutrons=Mass number−Atomic number=27−13=14\text{Number of neutrons} = \text{Mass number} - \text{Atomic number} = 27 - 13 = 14
This gives us an aluminum ion Al3+Al^{3+}, which will have 13 protons, 14 neutrons, and 10 electrons.

Step 2

magnesium burns in excess oxygen

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The balanced equation is:

2Mg+O2→2MgO2Mg + O_2 \rightarrow 2MgO

To find the maximum mass of magnesium oxide formed from 1.35g of magnesium, we first calculate the moles of magnesium:

Moles of Mg=massmolar mass=1.3524.0=0.05625 moles\text{Moles of } Mg = \frac{\text{mass}}{\text{molar mass}} = \frac{1.35}{24.0} = 0.05625 \text{ moles}

According to the balanced equation, 2 moles of Mg produce 2 moles of MgO. Hence, 0.05625 moles of Mg will produce 0.05625 moles of MgO. Now we calculate the mass of magnesium oxide:

Mass of MgO=moles×molar mass=0.05625×(24.0+16.0)=0.05625×40.0=2.25g\text{Mass of } MgO = \text{moles} \times \text{molar mass} = 0.05625 \times (24.0 + 16.0) = 0.05625 \times 40.0 = 2.25 g

Thus, the maximum mass of magnesium oxide that can be produced is 2.25g.

Step 3

sodium reacts with chlorine

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Answer

The electronic configuration of the sodium ion (Na+^+) after losing one electron is 2.8.
The electronic configuration of the chloride ion (Cl−^-) after gaining one electron is 2.8.8.

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