🔮 Trend Forecaster: Periodic Predictions
Cambridge IGCSE Chemistry (0620) · 15 Questions · 34 Marks · Data Analysis Focus
The boiling points of the halogens are: F₂ = −188°C, Cl₂ = −34°C, Br₂ = +59°C, I₂ = +184°C. Predict the physical state of bromine (Br₂) at room temperature (20°C). Justify your answer using the trend.
The melting points of Group I metals are: Li = 181°C, Na = 98°C, K = 63°C, Rb = 39°C. Predict whether caesium (Cs) would be solid or liquid at 35°C. Explain the trend.
The noble gases have the following boiling points: He = −269°C, Ne = −246°C, Ar = −186°C, Kr = −153°C. Predict whether xenon (Xe) would be a gas at −100°C.
Chlorine is a pale green gas at room temperature. Bromine is a red-brown liquid. Using the trend in Group VII, predict the appearance of iodine (I₂) at room temperature (20°C) and its physical state.
Sodium reacts vigorously with cold water, melting and moving across the surface. Potassium reacts more violently, igniting with a lilac flame. Predict what you would observe when rubidium (Rb) is added to cold water.
The densities (g/cm³) of Group I metals are: Li = 0.53, Na = 0.97, K = 0.86, Rb = 1.53, Cs = 1.87. A student claims the density of K should be between Na and Rb. Evaluate this claim and suggest why the actual density of K (0.86) appears to break the trend.
The melting points of Period 3 chlorides are: NaCl = 801°C, MgCl₂ = 714°C, AlCl₃ = 193°C, SiCl₄ = −68°C. Estimate the approximate melting point of PCl₃ and predict its bonding type.
The atomic radii (pm) of Group II elements are: Be = 112, Mg = 160, Ca = 197, Sr = 215. Estimate the atomic radius of barium (Ba) and explain the trend.
The first ionisation energies (kJ/mol) of noble gases are: He = 2372, Ne = 2081, Ar = 1521, Kr = 1351. Estimate the first ionisation energy of xenon (Xe) and explain the trend.
The electronegativity values of halogens are: F = 4.0, Cl = 3.0, Br = 2.8. Estimate the electronegativity of iodine (I) and suggest what value you would predict for astatine (At).
Element X is below potassium (K) in Group I of the Periodic Table. Predict and explain whether element X would be more or less reactive than potassium.
Fluorine reacts violently with most substances. Chlorine is reactive but less so. Bromine requires more forcing conditions. Predict whether iodine (I₂) would react with aqueous potassium bromide (KBr) and explain your reasoning.
Iron displaces copper from copper sulfate solution. Zinc displaces iron from iron sulfate solution. Predict whether copper would displace zinc from zinc sulfate solution. Use the reactivity series to justify your answer.
A mystery element Q is in Period 3. It reacts slowly with cold water but vigorously with dilute hydrochloric acid, forming a salt and hydrogen gas. Identify the most likely group of element Q and predict whether element Q would react with steam.
Carbon can reduce copper(II) oxide but cannot reduce aluminium oxide at laboratory temperatures. Explain this observation using the reactivity series and predict whether hydrogen could reduce aluminium oxide.
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