Thomas Edison State College
General Chemistry I with Labs (CHE-121)
Section no.: OL009
Semester and year: FEB2015
Written Assignment 2: Atomic Structure and Chemical Compounds
Answer all assigned questions and problems, and show all work.
1
What is the mass number of an iron atom that has 28 neutrons?
(3 points)
2
Calculate the number of neutrons of
239
Pu.
(3 points)
3
Write the appropriate symbol for each of the following isotopes: (a)
Z
= 11,
A
= 23; (b)
28,
A
= 64
(6 points)
(Reference: Chang 2.17)
a
23
b)
11
Na
28
4
Define, with two examples, the following terms: (a) alkali metals, (b) alkaline earth metal,
(c) halogens, and (d) noble gases
.
(8 points)
Z
=
64
Ni
(Reference: Chang 2.22)
a
Alkali metals (1A): Lithium (Li); Sodium (Na)
b
Alkaline earth metal (2A): Magnesium (Mg); Calcium (Ca)
c
Halogen (7A): Fluorine (F); Chlorine (Cl)
d
Noble gases (8A): Helium (He); Neon (Ne)
5
Identify the following as elements or compounds: (a) NH
3
, (b) N
2
, (c) CO, (d) Co, and
(e)
He.
(5 points)
6
