Module 3 - Periodic Table and Energy - Exam Questions Flashcards
Why does Xenon have a lower first ionisation energy than neon? (3)
Xe has a bigger atomic radius Xe has more shielding Lower nuclear attraction
Na melting point: 98°C Mg melting point: 639°C Explain the difference in melting point (3)
Mg ions have a greater charge Mg has more electrons Mg has greater attraction between ions and electrons
Sulphur exists as S8 molecules, and chlorine as Cl2. Explain why S has a higher melting point than Cl (2)
S8 and Cl2 have intermolecular forces S8 has stronger intermolecular forces than Cl2
Why does atomic radius decrease across a period? (3)
Nuclear charge increases Shielding remains the same Greater attraction
Why does first ionisation energy increase across a period? (3)
Atomic radius decreases Nuclear charge increases Shielding remains the same
Define first ionisation energy (3)
Energy change when each atom in 1 mole of gaseous atoms loses an electron
Explain why first ionisation energy of B is less than that of Be (2)
In B, electron being removed is at a higher energy An s electron is lost in Be and a p electron is lost in B
Explain why first ionisation energy of O is less than that of N (2)
In N, all 2p electrons are unpaired In O, 2p electron removed is paired so has repulsion that makes removal easier.
Describe what would be seen when a magnesium ribbon is added to excess dilute HCl (2)
Effervescence Mg dissolves
Describe the difference between Mg and Sr reacting with HCl (1)
Sr would be a quicker reaction
Predict the formulas of: Barium oxide and barium nitride (2)
BaO Ba3N2
Describe and explain the trend down group 2 of reactivity with water (5)
Reactivity increases down the group Atomic radii increase More shielding Nuclear attraction decreases Easier to remove outer electrons
A student reacts calcium exactly with HCl in solution. After adding more calcium it still reacts, explain this (2)
Calcium reacts with water producing calcium hydroxide Ca(s) + H2O(l) -> Ca(OH)2(aq) + H2(g)
Explain why samples of magnesium oxide become contaminated with magnesium carbonate over time (1)
MgO reacts with CO2
CO2 can be prepared by which reaction of carbonates (1)
Thermal decomposition
How do indigestion tablets containing CaCO3 work? (2)
CaCO3 neutralises HCl CaCO3 + 2HCl → CaCl2 + H2O + CO2
Write the equation and conditions for chlorine reacting with sodium hydroxide to form bleach (2)
2NaOH + Cl2 -> NaCl + NaClO + H2O Cold and dilute NaOH
Define disproportionation (1)
The simultaneous oxidation and reduction of the same element
Which reagent would need to be added to calcium iodide to prove it contained iodide ions? (1)
Silver nitrate
A solution contains CaBr2 and CaCl2, along with silver nitrate, which other reagent is added to prove iodide ions are present? (1)
Concentrated NH3
Which reaction type is forming AgCl from adding silver nitrate to chloride ions? (1)
Precipitation
Use bond breaking and bond making to explain why some reactions are exothermic (2)
Bond breaking absorbs energy and bond making releases energy More energy released then absorbed
Suggest three reasons why standard enthalpy changes of combustion are lower experimentally than theoretically (3)
Heat released to the surroundings Incomplete combustion Non-standard conditions
Define enthalpy change of combustion (2)
The enthalpy change for the complete combustion of 1 mol of a substance