The Periodic Table：練習問題

Which of the following statements about elements in The Periodic Table is true?

Consider the elements in Group 1 (alkali metals) and Group 17 (halogens) of the Periodic Table. As we move down each group, how do the melting points of the elements change, and what is the underlying trend in reactivity for Group 1 elements?

Elements X, Y, and Z have consecutive atomic numbers represented by the expressions \( n-1 \), \( n \), and \( n+1 \). If element Y is a noble gas located in Period 2 of the Periodic Table, which of the following statements correctly describes the positions and chemical properties of elements X and Z?

State the chemical symbol for the element Sodium and identify whether it is a metal or a non-metal.

Explain why the chemical reactivity of elements in Group 1 increases as the atomic number increases, whereas the reactivity of elements in Group 17 decreases as the atomic number increases, by referring to their electronic configurations and the distance between the nucleus and the valence shell.

The reactivity of elements in The Periodic Table varies according to their electronic arrangements. Compare the reactivity of Group 1 (alkali metals) and Group 18 (noble gases). Explain why Group 1 elements are highly reactive while Group 18 elements are chemically inert in terms of their outer shell electrons.

The Periodic Table organizes elements based on their atomic number and chemical properties. Use your knowledge of groups and periods to answer the following:

(a) Explain why elements in the same group of the Periodic Table exhibit similar chemical properties. (1 mark)
(b) Compare the properties of Metals and Non-metals. State two physical properties that are generally different between these two categories. (2 marks)
(c) Sodium (Group 1) and Magnesium (Group 2) are in the same period. Which element is more reactive? Justify your answer based on their position in the Periodic Table. (2 marks)

The Periodic Table organizes elements in a way that allows us to predict their properties. Use your knowledge of periods and groups to answer the following questions regarding elements in Period 3 and Group 1:

(a) Describe the trend in atomic size as you move from left to right across Period 3. (1 mark)

(b) Compare Sodium (Na) and Chlorine (Cl). Identify which one is a metal and which one is a non-metal. Explain how their positions in the Periodic Table relate to their ability to conduct electricity. (2 marks)

(c) Argon (Ar) is the last element in Period 3. Explain why Argon exists as single atoms (monoatomic) and does not react with other elements, referring to its electronic arrangement. (2 marks)

(d) When Magnesium (Mg) reacts with Oxygen (O), it forms Magnesium Oxide (\( \text{MgO} \)). Describe the change in the electronic arrangement of a Magnesium atom when it becomes a \( \text{Mg}^{2+} \) ion. (1 mark)

(e) Within Group 1 (alkali metals), Potassium (K) is placed below Sodium (Na). Explain why Potassium is more reactive than Sodium in terms of the distance between the nucleus and the outermost electron. (2 marks)