The Periodic Table: chemical periodicity：练习题

A liquid chloride of a Period 3 element reacts vigorously with water to form a cloudy mixture and a solution with a pH of approximately 2.
Which element is present in this chloride?

A student investigates the properties of two Period 3 chlorides, X and Y.
- X is a white solid that dissolves in water to form a solution with a pH of approximately 7.
- Y is a liquid at room temperature that reacts violently with water, producing white fumes and a solution with a pH of approximately 2.

Which row correctly identifies the structure and bonding of X and Y?

Which property shows a clear decrease across Period 3 from sodium to argon?

An element Z in Period 3 has the highest melting point in the period.
Which statement about element Z is correct?

The melting points of the Period 3 elements show a distinct trend. Which element has the highest melting point in Period 3, and what is the primary reason for this?

State the observation when a small piece of sodium metal is added to a trough of cold water and write the balanced chemical equation for the reaction, including state symbols.

Explain why the ionic radius of the phosphorus ion, \(P^{3-}\), is larger than the ionic radius of the silicon ion, \(Si^{4+}\), despite both ions having the same electronic configuration.

Describe the reaction of magnesium with water and with steam, providing balanced equations for both reactions and stating any differences in the observations.

Consider the elements sodium, magnesium, and aluminum in Period 3.
(a) State the trend in electrical conductivity for these three elements.
(b) Explain this trend by referring to the number of delocalised electrons and the nature of metallic bonding in these elements.
(c) When magnesium reacts with water, the reaction is much slower than that of sodium. Provide the equation for the reaction of magnesium with steam and state the observations made.

The chlorides of Period 3 elements exhibit a variety of behaviors when added to water.
(a) Describe what you would observe when phosphorus(V) chloride, \(PCl_5\), is added to water. Write an equation for the reaction and state the approximate pH of the resulting solution.
(b) Explain why sodium chloride, \(NaCl\), forms a neutral solution when dissolved in water, whereas silicon(IV) chloride, \(SiCl_4\), produces an acidic solution. Include an equation for the reaction of \(SiCl_4\) with water.