Periodic Table And Electronic Configuration
Class 10th Chemistry Part I Kerala Board Solution
- Which are the subshells in which electrons are filled in the s block elements of the third…
- Which are the subshells in which electrons are filled in the s block elements of the third…
- When the last electron of an atom was filled in the 3d subshell, the subshell electronic…
- Pick out the wrong ones from the subshell electronic configurations given below. a) 1s^2…
- The element X in group 17 has 3 shells. If so, a) Write the subshell electronic…
- The element Cu with atomic number 29 undergoes chemical reaction to form an ion with…
- Certain subshells of an atom are given below. 2s, 2d, 3f, 3d, 5s, 3p a) Which are the…
Let Us Assess
Question 1.Which are the subshells in which electrons are filled in the s block elements of the third period? Write the subshell electronic configuration of the last element of this period.
Answer:
The subshells in which electrons are filled in the s block elements of the third period are 1s,2s,2p,3s.
18Ar– 1s2 2s2 2p6 3s2 3p6
The s block elements of the third period are Na and Mg. So 1s,2s,2p,3s are the subshells in which electrons are filled.
The last element of third period is Argon which has atomic number 18.
Question 2.
Which are the subshells in which electrons are filled in the s block elements of the third period? Write the subshell electronic configuration of the last element of this period.
Answer:
The subshells in which electrons are filled in the s block elements of the third period are 1s,2s,2p,3s.
18Ar– 1s2 2s2 2p6 3s2 3p6
The s block elements of the third period are Na and Mg. So 1s,2s,2p,3s are the subshells in which electrons are filled.
The last element of third period is Argon which has atomic number 18.
Question 3.
When the last electron of an atom was filled in the 3d subshell, the subshell electronic configuration was recorded as 3d8. Answer the questions related to this atom.
• Complete subshell electronic configuration
• Atomic number
• Block
• Period number
• Group number
Answer:
Complete subshell electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s2 3d8
Atomic number = 28
Block = d-block
Period number = 4
Group number = 10
It is the electronic configuration of Ni. Ni is the element of d-block. Ni has atomic number 28 and it is the element of 4 period and 10 group in periodic table.
Question 4.
Pick out the wrong ones from the subshell electronic configurations given below.
a) 1s2 2s2 2p7
b) 1s2 2s2 2p2
c) 1s2 2s2 2p5 3s1
d) 1s2 2s2 2p6 3s2 3p6 3d2 4s1
e) 1s2 2s2 2p6 3s2 3p6 3d2 4s2
Answer:
The wrong electronic configurations are a), c), d).
In a) 1s2 2s2 2p7, p subshell can have a maximum of only 6 electrons.
In c) 1s2 2s2 2p5 3s1, According to Aufbau rule electrons will be filled first in that subshell which has less energy and when less energy subshell will become full filled then after this next subshell will be filled.
In d) 1s2 2s2 2p6 3s2 3p6 3d2 4s1, here 4s subshell will be full filled first and after this 3d subshell will fill because 4s subshell has less energy than 3d subshell.
Question 5.
The element X in group 17 has 3 shells. If so,
a) Write the subshell electronic configuration of the element.
b) Write the period number
c) What will be the chemical formula of the compound formed if the element X reacts with element Y of the third period which contains one electron in the p subshell?
Answer:
a) Subshell electronic configuration = 1s2 2s2 2p6 3s2 3p5
b) Period number = 3
c) Chemical formula when element X reacts with element Y= YX3
Element X has 3 shells means it is the element of 3 period. So, element X is Chlorine which is the element of 3 period and 17 group.
And element Y of the third period has 3 valence electrons because there is one electron in a 3p subshell and 2 electrons are in 3s subshell because s subshell filled first than p subshell. So, the chemical formula will be YX3.
Question 6.
The element Cu with atomic number 29 undergoes chemical reaction to form an ion with oxidation number +2.
a) Write down the subshell electronic configuration of this ion.
b) Can this element show variable valency? Why?
c) Write down the chemical formula of one compound formed when this element reacts with chlorine (17Cl).
Answer:
a) Cu2+ = 1s2 2s2 2p6 3s2 3p6 3d9
b) Yes. Because in d-block elements there is very small energy difference between the outer most s subshell and the penultimate d subshell. Hence under suitable conditions, the electrons of d subshell also take part in chemical reactions. So, Cu shows variable valency.
c) CuCl2
Cu shows +2 oxidation state and Cl shows -1 oxidation states in the chemical reaction so when these two elements will react then the chemical formula will be CuCl2.
Question 7.
Certain subshells of an atom are given below. 2s, 2d, 3f, 3d, 5s, 3p
a) Which are the subshells that are not possible?
b) Give the reason.
Answer:
a) 2d, 3f
b) In the first shell, there is only 1s subshell because this shell can have a maximum of only 2 electrons. So 1p subshell does not exist.
In the second shell, there are 2s and 2p subshells because this shell can have a maximum of 8 electrons. So 2d does not exist.
In the third shell, there are 3s, 3p, and 3d subshells because this shell can have a maximum of 18 electrons. So 3f does not exist.
In fourth shell, there are 4s, 4p, 4d and 4f subshells because this shell can have maximum of 32 electrons.
Extended Activities
Question 1.A part of the periodic table is given below. The symbols of elements given in the columns are not real.
a) Which are the elements having only one electron in the 4s subshell?
b) Which is the element in s block with the smallest atomic radius?
c) Which are the elements likely to form coloured compounds?
d) Which is the metal with the highest reactivity?
e) Which is the element with the least reactivity?
f) Which is the element in which the last electron is filled in the 4p sub shell? Find its atomic number.
g) Frame as many questions as possible to get each element in this table as the answer.
Answer:
a) A and C.
Since the element has one electron in a 4s subshell so from this we can find that this element of 4 periods and 1 group.
In d-block elements, the group number will be equal to the sum of total electrons of s subshell and the electrons in preceding d subshell. So A and C are the elements which have one electron in 4s subshell.
b) E
When we go from up to down in a group then a number of shells increases so the radius is also increased. Therefore, the element with the smallest radius in s block is E.
c) D and C
d-block elements (transition elements) form coloured compounds due to the presence of transition element ions. So, element D and C will form coloured compounds.
d) A
Since A is in the bottom in group 1 and the size of A is greater than the other metals due to increment in shells. So, A will loss his 1 electron more easily than other metals and will make compound easily.
e) F
Noble gases are less reactive due to full filled octet. So, F is less reactive.
f) H, Atomic number = 35
If we compare this periodic table ‘s part to the modern periodic table then H is Br which has atomic number 35 and so electronic configuration will be 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5. We can also calculate atomic number by count the elements 2+8+8+17=35.
g)
(i) The lightest metal in s-block?
(ii) The second lightest metal in s-block?
(iii) Which metal is important for strong bones?
(iv) Which transition element ‘s chloride is blue in the dry state?
(v) Which is the most reactive element in the periodic table?
(vi) Which noble gas is used in welding along with Helium?
(vii) Which element in halogen family is used for unsaturation test?
(viii) Which element is used with zinc to make brass alloy?