Which of the following is a pseudo-noble-gas electron configuration?

1)5 2) Al3+ and Se2- 3)S2−, Cl−, K+    and  Na+, Mg2+, Al3+ Explanation: 1) Atomic number of Fe is 26. This means it has 26 protons and 26 electrons. The electron configuration is as followed:
⇒Fe-1s2 2s2 2p6 3s2 3p6 3d6 4s2 ⇒a neutral atom of iron would have two electrons in the 4s sublevel and six electrons in the 3d sublevel. Fe3+ has 3 electrons less than Fe, so 23 electrons. ⇒The electron configuration for the Fe3+ ion is 1s2 2s2 2p6 3s2 3p6 3d5.  ⇒The positive charge of three in this ion shows that the atom lost three electrons. ⇒Electrons are taken from the outermost electron shell first, eliminating the two in the 4s sublevel. The other lost electron is then taken from the 3d sublevel. ⇒d subshell can occupy 10 electrons (in 5 orbitals). Pairing of electrons take place only after each orbital is singly occupied (Hund’s rule).

So, there are 5 electrons in the d subshell. So, each d orbital is singly occupied (unpaired).

This means there are 5 unpaired electrons in Fe3+ 2) noble gas configuration means they have 8 electrons on the the outer shell. ⇒Cr3+ : Cr has 24 electrons of which 1 electron on the outer shell, so Cr3+ is not in the noble gass electron configuration ⇒1
s
2  2
s
2  2
p
6  3
s
2  3
p
6  4
s
0  3
d
3 ⇒Note that it is  4
s
1  3
d
5  and not  4
s
2  3
d
4  because a half filled  d  orbital is more stable than a partially filled  d  orbital. ⇒Al3+: Al has 13 electrons, of which 3 are on the outer shell. Al3+ has 3electrons less, this means it loses the 3 electrons on the outer shell. So Al3+ has 10 electrons, of which 8 on the outer shell. This means it’s in the noble gas electron configuration. ⇒The electron configuration of an aluminum ion, Al3+, is 1s2, 2s2, 2p6 ⇒Se2-: Se has 34 electrons, of which 6 are on the outer shell. Se2- has 2 electrons more, this means it gains 2 electrons on the outer shell. So Se2- has 36 electrons, of which 8 on the outer shell. This means it’s in the noble gas electron configuration. ⇒1
s
2  2
s
2 2
p
6  3
s
2  3
p
6  3
d
10  4
s
2  4
p
6 3) Isoelectronic species means those species which have same no. of total electrons : S2-, Cl-,K+ : ⇒S has 16 electrons, S2- has 2 electrons more so 18 electrons ⇒Cl has 17 electrons,Cl- has 1 electron more so 18 electrons ⇒K has 19 electrons, K+ has 1 electron less so 18 electrons ⇔This is an isoelectronic set because they all have 18 electrons ⇔in order of increasing radius : S2- > Cl- > Al3+ : because in Sé- are the most electrons added. Na+,Mg2+,Al3+ ⇒Na has 11 electrons, Na+ has 1 electron less so 10 electrons ⇒Mg has 12 electrons, Mg2+ has 2 electrons less so 10 electrons ⇒Al has 13 electrons, Al3+ has 3 electrons less so 10 electrons ⇔This is an isoelectronic set because they all have 10 electrons ⇔in order of increasing radius : Na+ >Mg2+ > Al3+ : because in Sé- are the most electrons added. Na+,K+,Li+ ⇒Na has 11 electrons, Na+ has 1 electron less so 10 electrons ⇒K has 19 electrons, K+ has 1 electron less so 18 electrons ⇒Li has 3 electrons, Li+ has 1 electron less so 2 electrons ⇔This is no isoelectronic set 4) ⇒Pb is a metal. It’s part of the p-block and the carbon group. It forms a Pb-ion ( Pb2+) ⇒ K is an alkalimetal ( so part of the metals). It forms K-ion (K+) ⇒ Xe is a nonmetal and part of the noble gasses. It doesn’t form an ion, because it has 8 electrons on the outer shell, why it’s stable. ⇒Al is a metal. It forms an Al3+ ion ⇒Iodine is a halogene., so a nonmetal. It forms I-, ion

1 Explanation: For non metals to attain a noble gas configuration, they gain the number of electrons needed to attain the noble gas configuration of the noble gas at the end of their periods. This means that these non metals would only take up the configuration of the last element on their periods which of course is always a noble gas. The last element on the hydrogen period or more conservatively the only other element on the hydrogen period is helium, with an atomic number of 2. The atomic number is the number of protons in he nucleus of an atom. For an electrically neutral atom, the number of electrons equal the number of protons. Hence we can deduce that helium has 2 electrons while hydrogen has one electron. Thus for it to attain the configuration of helium, it just needs to gain one more electron

2 electrons E. neon Explanation: Metals lose electrons under certain conditions to attain a noble gas electron configuration. Magnesium has 12 electrons and its electron configuration is 1s² 2s² 2p6⁶ 3s² When magnesium loses 2 electrons, it acquires the electron configuration of neon (10 electrons).

Any element that would need to rid itself of three or more electrons to achieve a noble gas configuration (a transition metal), is extremely unlikely to do so.
Instead, an element will lose its incomplete sublevel (a lone 4s, 5s, etc. electron) that results with 18 electrons in the highest occupied energy level, and all of its orbitals filled. It now has a pseudo noble-gas electron configuration.
Example Zn2+, Cd2+ ions

D) He Explanation: Helium is in the first period. It only has 1 valence electron so it’s very reactive. (This could be completely wrong and I’m sorry if it is.)

Answer 6

Lithium loses one electron to fluorine and forms ionic bond, having formula . Explanation: Lithium is the element of the group 1 and period 2 which means that the valence electronic configuration is .
Fluorine is the element of the group 17 and period 2 which means that the valence electronic configuration is .
Thus, lithium loses 1 electron and become positively charged. Fluorine on the other hand accepts this electron and become negatively charged. This is done in order that the octet of the atoms are complete.  These both ions then form ionic bond as their will be electrostatic interaction between the two oppositely charged ions. Thus, the formula of calcium chloride is .

Answer 7

The correct statement is : The atom gains five electrons. Explanation: Aluminum has the atomic number of 13. The electronic configurations of aluminum is given: So, in order to gain stability of noble gases aluminium ether have to gain 5 electrons or loose three elections. By gaining five electrons its electron configuration gets same as that of the argon’s electronic configuration. So, the charge on the aluminium ion will be (5-).

The two statements are all True for group 7 and 8 elements. Explanation: The Group 7 elements are known as the halogens. They are reactive non-metals and are always found in compounds with other elements. Chlorine, bromine and iodine are all halogens. Chlorine, bromine and iodine are the three common Group 7 elements. Group 7 elements form salts when they react with metals. The term ‘halogen’ means ‘salt former’. In addition to the discription given to norble gases in the question which is true, norble gases;     are inert gases located on the right of the periodic table.     have a full-set of valence electrons, so they’re stable, unreactive     are colorless, odorless and tasteless.     have low melting and low boiling points.     can be found in small amounts in the Earth’s crust and the Earth’s atmosphere.

To achieve a noble gas electronic configuration, the overall charge has to be 0 as noble suggest stable. For such configuration to happen, in your syllabus, when the question mentions LOSING / GAINING electrons, it is referring to ionic bonding. For ionic bonding to occur, metal atom must be bonded to a non-metal atom. A metallic ion like sodium ion is always +1 charge A non-metallic ion like chlorine ion is always -1 charge. So for a stable Sodium Chloride/NaCl to achieve a noble(stable) state, an electron will be lost chlorine ion where this electron will be gained by sodium ion. When chlorine ion (-1 charge) loses an electron, it becomes 0 charge, which is stable. When sodium ion(+1 charge) gains an electron, it becomes 0 charge which is stable. And hence both are stable and formed the stable noble compound called NaCl.

0

Silver has to give up one electron in order to achieve a pseudo-noble gas electronic configuration.

Leave a Comment