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2019 is the 150th anniversary of the periodic table's creation by Dmitri Mendeleev - Scottish Highers Chemistry - Question 2 - 2019
Question 2
2019 is the 150th anniversary of the periodic table's creation by Dmitri Mendeleev. The patterns identified by Mendeleev form the basis of the modern periodic table.... show full transcript
Worked Solution & Example Answer:2019 is the 150th anniversary of the periodic table's creation by Dmitri Mendeleev - Scottish Highers Chemistry - Question 2 - 2019
Step 1
Explain why the first ionisation energy shows an increase going from lithium to neon.
Answer
The first ionisation energy increases from lithium to neon due to the increasing nuclear charge, which causes electrons to be held more tightly. As we move across the period, the number of protons increases, enhancing the attraction between the nucleus and electrons.
Step 2
Explain why the first ionisation energy of potassium is less than the first ionisation energy of lithium.
Answer
The first ionisation energy of potassium is less than that of lithium because potassium has an additional electron shell (more shells). This increases electron shielding, which reduces the effective nuclear charge felt by the outermost electron, making it easier to remove.
Step 3
Step 4
Explain fully the increase between the 5th and 6th ionisation energies of nitrogen.
Answer
The increase between the 5th and 6th ionisation energies of nitrogen is significant because removing the 6th electron involves overcoming a stronger attraction. This electron is removed from a more stable, fully filled subshell, which requires much more energy.
Step 5
Explain fully why the ionic radius of phosphorus is greater than the ionic radius of aluminium.
Answer
Phosphorus has more electrons (15) compared to aluminium (13), which gives it a greater ionic radius. Additionally, phosphorus forms anions (like P^3-) while aluminium typically forms cations (like Al^3+). The added electron-electron repulsion in phosphorus's anion contributes to a larger radius.
Step 6
Predict whether the structure of barium oxide, BaO, is similar to caesium chloride or sodium chloride.
Answer
To predict the structure of barium oxide, we calculate the radius ratio. The radius ratio for BaO is approximately 0.64. Since this is closer to the radius ratio of sodium chloride (0.52) than caesium chloride (0.96), the structure of BaO is more similar to sodium chloride.