f.4 chem atomic structure
1..which of the following statements concerning elements in the same group of the periodic table are correct?
(1)they all have the same number od outermost shell electrons in their atoms.
(2)the reactivity always increases down the group.
(3)the number of occupied electron shells in their atoms increases down the group.
A. (1)and (2)only
B (1)and (3)only
C (2)and (3)only
2..elements X has an isotope 31.15 X which of the following statements concerning X IS/ARE CORRECT?
(1)X belongs to group V of the periodic table.
(2)X is a metal.
(3) X has very high melting and boiling points.
C (1)and (3)only
D (2)and (3)only
- 土扁Lv 77 年 前最佳解答
The answer is : B. (1) and (3) only
For halogens (Group VII elements), the reactivity decreases down the group.
The answer is : A. (1) only
Atomic number = 15
Electronic configuration : 2, 8, 5
The atom has 5 electrons in the outermost shell. Hence, the element belongs toGroup V.
Group V elements are non-metals.
X has low melting point and boiling point.
X has simple molecular structure, and the molecules are held together by weakvan der Waals forces.資料來源： 土扁