The Periodic Table: chemical periodicity：练习题

Which element in Period 3 has the highest melting point?

A solid oxide of a Period 3 element is added to water. The resulting solution has a pH of approximately 2.
Which oxide could this be?

An element M is in Period 3. Its oxide is insoluble in water but dissolves in both dilute hydrochloric acid and hot aqueous sodium hydroxide.
Which statement about element M is correct?

Which statement correctly describes the trend in atomic radius across Period 3 from sodium to chlorine?

What are the maximum oxidation numbers of the elements magnesium, aluminum, and sulfur in their respective oxides?

State the variation in the maximum oxidation number of the Period 3 elements from sodium to sulfur in their oxides.

Explain why silicon has a much higher melting point than phosphorus.

Explain why a solution of aluminium chloride, \( \text{AlCl}_3 \), is acidic while a solution of magnesium chloride, \( \text{MgCl}_2 \), is neutral.

(a) State and explain the trend in atomic radius for the elements across Period 3 from sodium to chlorine.
(b) Explain why the ionic radius of phosphorus, \(P^{3-}\), is significantly larger than the ionic radius of silicon, \(Si^{4+}\).

The melting points of the elements in Period 3 show a specific trend: Na (371 K), Mg (923 K), Al (933 K), Si (1683 K), P (317 K), S (392 K).
(a) Explain the increase in melting point from sodium to aluminium.
(b) Explain why silicon has the highest melting point in the period.
(c) Explain the decrease in melting point from silicon to phosphorus.