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Ionic compounds contain ions - Edexcel - GCSE Chemistry - Question 4 - 2016 - Paper 1
Question 4
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 - Question 4 - 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 consider the balance between electrons and protons. A negative ion has more electrons than protons.
- Particle W: 9 electrons, 9 protons (neutral)
- Particle X: 10 electrons, 12 protons (neutral)
- Particle Y: 16 electrons, 12 protons (negative ion, as it has more electrons than protons)
- Particle Z: 18 electrons, 16 protons (negative ion, as it has more electrons than protons)
Therefore, both particle Y and particle Z can be classified as negative ions. However, the specific answer is that either Y or Z is correct.
Step 2
Calculate the relative formula mass of calcium nitrate, Ca(NO₃)₂.
Answer
The formula of calcium nitrate is Ca(NO₃)₂. To calculate its relative formula mass, we first break it down:
- Calcium (Ca): 1 atom × 40 = 40
- Nitrate (NO₃): Each nitrate has 1 nitrogen and 3 oxygens.
- Nitrogen: 2 atoms × 14 = 28
- Oxygen: 6 atoms × 16 = 96
Now, we add all the values together to find the total:
Thus, the relative formula mass of calcium nitrate is 164.