Вопрос
Answer (score: 1): Z-Which two atoms of elements lack two electrons to complete the external level? (1) Br (2) Se 3) 0 4) F 5) Li Answer (score: 1):
Решения
4.2
(304 Голоса)
Жанна
профессионал · Репетитор 6 лет
Ответ
2.3
Объяснение
The question is asking which two atoms of elements lack two electrons to complete their outermost electron shell. Atoms strive to have a full outermost electron shell, which typically consists of eight electrons. This is known as the octet rule. 1. Br (Bromine) has an atomic number of 35, which means it has 35 electrons. Its electron configuration is [Ar] 3d10 4s2 4p5. It has seven electrons in its outermost shell and needs one more electron to complete it. 2. Se (Selenium) has an atomic number of 34, which means it has 34 electrons. Its electron configuration is [Ar] 3d10 4s2 4p4. It has six electrons in its outermost shell and needs two more electrons to complete it.3. O (Oxygen) has an atomic number of 8, which means it has 8 electrons. Its electron configuration is 1s2 2s2 2p4. It has six electrons in its outermost shell and needs two more electrons to complete it.4. F (Fluorine) has an atomic number of 9, which means it has 9 electrons. Its electron configuration is 1s2 2s2 2p5. It has seven electrons in its outermost shell and needs one more electron to complete it.5. Li (Lithium) has an atomic number of 3, which means it has 3 electrons. Its electron configuration is 1s2 2s1. It has one electron in its outermost shell and needs one more electron to complete it.From the above analysis, Se and O are the two elements that lack two electrons to complete their outermost electron shell.