Answer all assigned questions and problems, and show all work. What is the mass
ID: 498079 • Letter: A
Question
Answer all assigned questions and problems, and show all work.
What is the mass number of an iron atom that has 28 neutrons? (3 points)
(Reference: Chang 2.13)
Calculate the number of neutrons of 239Pu. (3 points)
(Reference: Chang 2.14)
Write the appropriate symbol for each of the following isotopes: (a) Z = 11, A = 23; (b) Z = 28, A = 64 (6 points)
(Reference: Chang 2.17)
Define, with two examples, the following terms: (a) alkali metals, (b) alkaline earth metal, (c) halogens, and (d) noble gases. (8 points)
(Reference: Chang 2.22)
Identify the following as elements or compounds: (a) NH3, (b) N2, (c) CO, (d) Co, and (e) He. (5 points)
Give the numbers of protons and electrons in each of the following: (a) Na+, (b) Ca2+, (c) Al3+, (d) I–, (e) O2–, (f) N3–, and (g) He. (14 points)
Write the molecular formula of glycine, an amino acid present in proteins.
Carbon = 2 atoms
Hydrogen = 5 atoms
Nitrogen = 1 atom
Oxygen = 2 atoms. (3 points)
(Reference: Chang 2.47)
Which of the following compounds are likely to be ionic? Which are likely to be molecular? (a) SiCl4, (b) LiF, (c) BaCl2, (d) B2H6 , (e) KCl, and (f) C2H4 (6 points)
(Reference: Chang 2.49)
What is the difference between inorganic compounds and organic compounds? (4 points)
(Reference: Chang 2.51)
Name the following compounds. (22 points)
Na2CrO4
K2HPO4
HBr (gas)
HBr (in water
Li2CO3
K2Cr2O7
FeO
PF3
NH4NO2
Al(OH)3
TiCl4
CuSO4 5H2O
Write the formulas for the following compounds: (18 points)
rubidium nitrite
potassium sulfide
calcium hydrogen phosphate
iodine heptafluoride
ammonium sulfate
copper (II) nitrite
calcium hydroxide
dihydrogen sulfide
sodium hydride
The following table gives the number of electrons, protons, and neutrons in atoms or ions of four elements, identified only as A, B, C, and D. Write the isotopic symbol for each element. (8 points)
Atom or Ion of Element
No. of protons
No. of electrons
No. of neutrons
Isotopic symbol
A
5
5
5
B
7
10
7
C
19
18
20
D
30
28
36
Atom or Ion of Element
No. of protons
No. of electrons
No. of neutrons
Isotopic symbol
A
5
5
5
B
7
10
7
C
19
18
20
D
30
28
36
Explanation / Answer
* Mass number of Fe = Number of protons in Fe + number of neutrons in Fe
= Atomic number of Fe + Number of neutrons in Fe
= 26 + 28
= 54
* *
Number of neutrons = Mass number - atomic number
= 239 - 94
= 145
* * *
(a) 2311Na
(b) 6428Ni
****
(a) Alkali metals: Group '1' elements are called as alkali metals. Because their oxides solution are basic in nature and the elemetns are metllic in nature.
ex: Li, Na, K, Rb, Cs
(b) Alkaline earth metals: Group '2' elements are called as alkaline earth metals. Because of their oxides and hydroxide solutions are basic in nature. And their oxides are resistant to heat. The elements are metallic in nature.
ex: Be, Mg, Ca, Sr, Ba
(c) Halogens: The elemetns which can form the sea slats.
Ex: F, Cl, Br, I
(d) Noble gases: The elements which are inert in nature but exhibits reactivity at extreme conditions.
Ex: He, Ne, Ar, Kr, Xe, Rn
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