KASDI MERBAH-OUARGLA UNIVERSITY
Faculty of Hydrocarbons, Renewable Energies, Earth and Universe Sciences
Department of Drilling and Oil Site Mechanics
Academic year: 2024/2025 Module: Structure of the matter Level: 1: 1st year STH
TD Series No. 4: Periodic classification
Exercise 01:
1. Consider the following atoms: 7N, 17Cl, 19K, 21Sc, 24Cr, 26Fe, 29Cu, 33As,
Give the electronic configurations of the atoms. Show the valence electrons for each
atom. In deduce the number of valence electrons. Give their position in the periodic table
Are these atoms paramagnetic or diamagnetic? Justify.
2. Give the most stable ion: Cl, K, Fe
3. Molybdenum 42Mo and silver 47Ag both exhibit an anomaly to the Klechkowsky rule.
To write the expected configuration while respecting Klechkowsky's rule, then compare
to the actual configuration (see periodic table course).
4. For level n=2, how many types of atomic orbitals are there? Name them. For each of
the orbitals atomic, give the quantum numbers which correspond to it
5. Associate the orbitals thus defined 3s, 4p, 6d and 5f with electronic wave functions
Exercise 02:
Give the electronic configurations, the atomic number and the group of A, B, C knowing
that:
a- A3+ has the structure of Neon, a noble gas which belongs to the second period.
b- B belongs to the same period of A. B is missing 2 electrons to have the configuration of
a rare gas.
c-C + has the noble gas configuration which belongs to the period of B.
Exercise 03: Consider the following elements of the periodic table: A, B, X and Y
A is an element of the 4th period with 3rd singles. B has an atomic number corresponding
to: ZB= 2ZA – 14. The last electron of element X is characterized by the following four
quantum numbers: (n=4; l=2; m=0; s=+1/2). Element Y belongs to the same column as
32Ge and to the same period as 16S
1) Give the possible electronic configurations for element A.
2) If element A belongs to column 5
a) What would be the atomic number of element A?
b) Deduce the atomic number of element B and give its electronic configuration
3) From the given quantum numbers, give the electronic configuration and the atomic
number of elements
4) Give the electronic configuration of 32Ge and 16S
- Deduce the electronic configuration of element Y and its atomic number
Exercise 04:
1. Establish the 19K and 21Sc electronic configuration
2. Using Slater's rules, determine the effective nuclear charge of the last electron in 19K
and 21Sc
3. Calculate the 1first ionization energy for 21Sc and the second ionization energy for 19K.
Data for Slater calculations: En= - 13.6 Z2/n2
; rn= 0.53 n2 /Z
Slater screen constants:
Electron type Same group electron Electron of groups (n-1) Electron of groups < (n-1)
1s 0.30
ns , np 0.35 0.85 1.00
nd , nf 0.35 1.00 1.00
4. Compare the atomic radius, ionization energy and electronegativity of the following
elements: 55Cs, 9F, 19K, 7N, 3Li
