Page 62 - Chemistry eBook

more positively charged electrons.
(3) A positively charged nucleus is surrounded
by one or more negatively charged electrons.
(4) A positively charged nucleus is surrounded
11 The eleme arranged in
(1) atomic (2) atomic
by one or more positively charged electrons.
Sample Regents Questions
12 What is th most electron with the most energy? ZnO?
5 Which atom in the ground state has an outer-
(1) Cs (3) Li (2) K (4) Na
6 Which particle has the least mass?
(1) zinc oxi (2) zinc oxa
13 Which ato configuratio
(1) neon (2) radon
(1) alpha particle (2) beta particle
Choice # 1
Jan 2(30)12n#eu5tron (4) proton
Answer
P.S./Chem.–Jan. ’12
[2]
Explanation:
1. Let’s check out Reffy (p. 9) to see which one of these elements has the highest
atomic number. The atomic numbers of the four elements listed are 55, 19, 3, and 11. 2. Atomic number = number of electrons. The more electrons there are, the more shells
they occupy.
3. If Cs has 55 electrons, it needs 4 shells (2-8-18-27). The other atoms only need two or
three shells. The fourth shell has more energy than the third and second shell. Because C has the most shells, its outermost electron has the most energy.
m n
e
d l
m
62 © UNIT 2: ATOMIC STRUCTURE