Group 1 (alkali metals) – lithium, sodium and potassium：練習問題

Which gas is produced when sodium reacts with water?

Which of the following observations is unique to the reaction of potassium with water compared to lithium or sodium?

A student observes the reaction of an alkali metal with water. The metal floats on the surface, melts into a shiny ball, and moves rapidly while fizzing. A small lilac flame is briefly seen. Which statement best explains the reactivity of this metal compared to others in the same group in terms of its electronic configuration?

Which of the following describes the correct trend in melting points as you go down Group 1 from lithium to potassium?

What is the correct electronic configuration of a sodium atom (atomic number 11)?

State the color observed in a flame test for sodium ions and potassium ions.

Predict the observation when a small piece of rubidium is added to water, based on the trend in reactivity seen in lithium, sodium, and potassium. Provide a reason for your prediction.

Explain why potassium is more reactive than lithium. Your answer should refer to the distance between the outer electron and the nucleus, and the strength of the attraction between them.

Lithium, sodium, and potassium are all alkali metals found in Group 1 of the Periodic Table.

a) Describe two observable differences when a small piece of lithium, sodium, and potassium are separately added to water.

b) Explain the trend in reactivity of these three elements with water, referring to their atomic structure.

c) Write a balanced chemical equation for the reaction of sodium with water.

A student investigates the properties and reactivity of the Group 1 elements: lithium, sodium, and potassium.

a) When a small piece of potassium is added to a large trough of water containing universal indicator, it reacts much more vigorously than lithium.

i) State two observations that are unique to the reaction of potassium with water compared to the reaction of lithium with water. (2)

ii) Write a balanced chemical equation, including state symbols, for the reaction between potassium and water. (2)

b) The reactivity of Group 1 elements increases down the group. Explain this trend in terms of the electronic configurations of the atoms. (3)

c) Rubidium is the element directly below potassium in Group 1. Predict two properties of rubidium based on its position in the group. (1)