CHEM 1405 - CHAPTER: 4 MODELS OF THE ATOM
PRACTICE PROBLEMS
Q1. Analysis of 3.800g of glucose gives 1.520g of carbon, 0.2535g of hydrogen and
2.027g of oxygen. Calculate the mass percentage of each element.
Q2: Find out the sign and magnitude of charge of the following species and also the
atomic number and atomic mass
a. 12 p, 12 n and 10 e(b). 6 p, 8 n and 6 e(c). 8 p, 8 n and
10e
Q3: Find the number of protons, neutrons and electrons.
a) 40Ca
b) 31P
c) 238U
20
15
92
Q4: Complete the following table by filling the blanks.
p
n
e
mass
16
__
__
32
___
___
17
35
___
144
___
234
6
8
____
___
Element
Q5: Calculate the number of electrons, protons and neutrons in the following
species.
238
232
58
80
2+
-92U
90Th
28 Ni
35 Br
Q6: Calculate the average atomic mass of Ne, which is composed of three different
isotopes of atomic masses 20.00 amu, 21.00 amu and 22.00 amu. The natural
abundance of each isotope is 90.92%, 0.257% and 8.82% respectively.
Q7: Mg consists of three isotopes of masses 24.0 amu, 25.0 amu and 26.0 amu. With
abundances of 78.70%, 10.13% and 11.17% respectively. Calculate the average
atomic mass of Mg.
Q8. How many electrons are there in a p sub shell?
Q9. What is the maximum number of electrons in a d sub shell?
Q10. What happens to the energy of shells as it goes farther away from the nucleus?
Q11. Find the number and type of sub shells in the 4th and 5th shell of an atom.
Q12: How many and what kind of sub shells are allowed in the energy shell with
principal quantum number 5? Also, calculate the maximum number of electrons.
Q13. Find the electronic configuration and the core configuration of the following
elements.
Carbon, Sodium, Aluminum, Phosphorus, Nitrogen, Neon, Oxygen, Scandium,
Iron, Chromium and Copper
Q14: Name the elements described by the following electronic configuration.
a)
He
2s2,2p1
b)
Ne
3s2,3p5
c)
Q15: Write down the electronic configuration of K+ , Cl - ,
Ar
Ca 2+
Q16: Find compact electronic configuration for the following elements.
a) Br b) S c) C
d) Fe
4s2
,
N
3-