Classification of periodic elements Flashcards
How would you justify the filling of 18 electrons in the 5th period of the periodic table?
the 5th. It’s the feeling of 5th shell. This period has 4d, 5s, 5p available orbitals. The total number of available orbitals are 9 and therefore the maximum number of electrons that can be accommodated is 18.
Arrange the following elements in the increasing order of their metallic character
Si, Be, Mg, Na, P
P<Si<Be<Mg<Na
On the basis of quantum numbers, justify that the sixth period of the period of the periodic table should have 32 elements.
The sixth period of the periodic table begins with n=6. It involves the filling of 6s, 4f, 5d and 6p subshell in the increasing order of energy. The total number of orbitals available are 16 and therefore, the maximum number of electrons that can be accommodate is 32. Thus the sixth period of the periodic table should have 32 elements.
halogen configuration
ns2np5
The first I.E values of the 3rd period elements. Na, Mg, Si are respectively 496, 737 and 786. Predict whether the 1st IE value for Al will be more close to 575 or 760 mol-1 respectively. Justify
It will be more close to 575 kJ mol-1 because the value of AL should be lower than that of Mg. This is due to effective shielding of 3p electrons form the nucleus by 3s electrons.
the E.G.E of Cl is 349 kJmol-1. How much energy is kJ is released when 1gm of chlorine is converted completely to Cl- ions in the gaseous state?
energy released when 35.5 g (1 mol) is completely converted= 349 kJ
so when 1 g of Cl=349/35.5*1=9.83kJ
WHat is the significance of the terms “isolated gaseous atom” and ground state while defining the IE and E.G.E?
Isolated gaseous atom means that the atom should be free from other atoms in the gaseous state. No energy should be required to separate it further from other atoms. Ground state means the lowest state possible for that atom. These terms are used for comparison purposes.
Energy of an electron in the ground state of the H atom is -2.18* 10^-18. Calculate the IE of atomic hydrogen in terms of J mol-1
IE is the amount of energy required to remove the electron form ground state to infinity.
Energy at ground state = -2.1810^-18J
Energy of e- at infinity=0
therefore the energy to remove the e- = 0-(-2.18 10^-18)=2.1810^-18
Amount of energy required to remove one mol of e- from 1 mol of H atoms=2.18 * 10-186.02210^23
therefore IE of H= 13.13010^5 Jmol-1
O has lower IE than N and F
Oxygen has 4 e- in 2p orbitals and 2 of the four 2p electrons must occupy the same 2p orbital resulting in increased e-e repulsion. On the other hand, N has a stable half-filled configuration, while F has greater nuclear charge. Therefore, o has IE less than N as well as F.
Which of the elements Na, Mg, SI and P would have a greater difference between the 1st and 2nd IE ? explain
Among these elements, Na is an alkali metal and has only one electron in its valence shell (3s^1). Therefore, Its IE is very low. After the removal of one e-, it acquires neon gas configuration i.e, (1s^2 2s^2 2p^6). Therefore, its IE2 is expected to be very high. Consequently, the difference in first and second ionization enthalpies would be greatest in case of Na.
