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Ionic compounds contain ions - Edexcel - GCSE Chemistry: Combined Science - Question 3 - 2016 - Paper 1
Question 3
Ionic compounds contain ions. (a) The numbers of electrons, neutrons and protons in four particles, W, X, Y and Z, are shown in Figure 5. Explain which particle, W... show full transcript
Worked Solution & Example Answer:Ionic compounds contain ions - Edexcel - GCSE Chemistry: Combined Science - Question 3 - 2016 - Paper 1
Step 1
Explain which particle, W, X, Y or Z, is a negative ion.
Answer
To determine which particle is a negative ion, we need to compare the number of electrons and protons for each particle. A negative ion occurs when there are more electrons than protons, resulting in a net negative charge.
- For particle W: 9 electrons, 9 protons (neutral)
- For particle X: 10 electrons, 12 protons (net charge -2, negative ion)
- For particle Y: 16 electrons, 16 protons (neutral)
- For particle Z: 18 electrons, 18 protons (neutral)
Thus, particle X is the negative ion because it has more electrons than protons.
Step 2
Calculate the relative formula mass of calcium nitrate, Ca(NO₃)₂.
Answer
To calculate the relative formula mass of calcium nitrate, we need to sum the atomic masses of all the atoms in the formula Ca(NO₃)₂.
- Calcium (Ca): 1 × 40 = 40
- Nitrogen (N): 2 × 14 = 28
- Oxygen (O): 6 × 16 = 96 (since there are 3 oxygen atoms in each nitrate ion and there are 2 nitrate ions)
Now, add them together:
Thus, the relative formula mass of calcium nitrate is 164.