Tag: classification of elements- the periodic table

Questions Related to classification of elements- the periodic table

Define the relation among the $EN,\,IE\;and\;E.A.$

chemistry classification of elements- the periodic table periodic trends in physical properties properties and trend trends in periodic table electronic configuration and valency electron configuration

  1. $EN=\displaystyle\frac{IE\times EA}{2}$

  2. $EN=IE+EA$

  3. $2EN=IE-EA$

  4. $EN=\displaystyle\frac{IE+EA}{2}$

  5. $EN=\displaystyle\frac{IE-EA}{2}$

Show answer
Correct Option: D
Explanation:

The correct relationship is $EN = \dfrac {IE+EA}{2}$
According to mulliken's scale, the electronegatiity is the average value of ionization potential and electron affinity of an atom.

An element $X$ has $IP = 1681$ kJ/mole and $EA =-333$ kJ/mole then its electronegativity is:

chemistry classification of elements- the periodic table periodic trends in physical properties properties and trend trends in periodic table electronic configuration and valency electron configuration

  1. $(1681 + 333) / 544$

  2. $(1681 - 333 )/ 544$

  3. $(1681 + (-333)) / 2$

  4. $\dfrac{208\sqrt{1681+333}}{544}$

Show answer
Correct Option: C
Explanation:

Robert S. Mulliken proposed that the arithmetic mean of the first ionization energy ($E i$) and the electron affinity ($E _{ea}$) should be a measure of the tendency of an atom to attract electrons. As this definition is not dependent on an arbitrary relative scale, it has also been termed absolute electronegativity, with the units of kilojoules per mole or electron volts.
                                        <img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/44e7db9c2cb1be249c807e9435c4d11788ea2efc" class="mwe-math-fallback-image-inline" alt="\chi =(E{\rm {i}}+E_{\rm {ea}})/2\,">

The ${ Z } { eff }$ for
3d electron of Cr
4s electron of Cr
3d electron of ${ Cr }^{ 3+ }$
3s electron of ${ Cr }^{ 3+ }$ are _________ respectively.

chemistry classification of elements- the periodic table periodic trends in physical properties properties and trend trends in periodic table electronic configuration and valency electron configuration

  1. 4.6, 2.95, 4.95, 8.05

  2. 4.95, 2.05, 4.6, 8.05

  3. 4.6, 2.95, 5.3, 12.75

  4. none of these

Show answer
Correct Option: C
Explanation:

Cr ${ 1s }^{ 2 }\quad { 2s }^{ 2 }\quad { 2p }^{ 6 }\quad { 3s }^{ 2 }\quad { 3p }^{ 6 }\quad { 3d }^{ 5 }\quad { 4s }^{ 1 }$

${ 24 }^{ - }$
Using later's rule:
for $3de^{ - }\quad { Z } _{ eff }=24-(4\times 0.35)-(18\times 1)=4.6$
for $4se^{ - }\quad { Z } _{ eff }=24-(0\times 0.35)-(13\times 0.85)-(10\times 1)=2.95$
$Cr^{ 3+ }\quad ({ 1s }^{ 2 }\quad { 2s }^{ 2 }\quad { 2p }^{ 6 }\quad { 3s }^{ 2 }\quad { 3p }^{ 6 }\quad { 3d }^{ 3 })$
for $3de^{ - }\quad { Z } _{ eff }=24-(2\times 0.85)-18=5.3$
for $3se^{ - }\quad { Z } _{ eff }=24-(7\times 0.35)-(8\times 0.85)-(2\times 1)=12.75$
                                         ${ s }^{ 1 }p^{ 6 }$           $2({ s }^{ 2 }p^{ 6 })$                    ${ 1s }^{ 2 }$

In laboratory burners, we use

chemistry classification of elements- the periodic table introduction to periodic table necessity of classification need for classification

  1. Producer gas

  2. Oil gas

  3. Gobar Gas

  4. None of the above

Show answer
Correct Option: B
Explanation:

In laboratory burners , oil gas is generally used oil gas is mixture of $CH _4 + CO + CO _2 + H _2$

Hence, the correct option is B

Who was the first to classify the elements into metals and non-metals?

chemistry classification of elements- the periodic table introduction to periodic table necessity of classification need for classification

  1. Meyer

  2. Mendeleev

  3. Lavoisier

  4. None of the above

Show answer
Correct Option: C
Explanation:

Lavioser was the first person to classify elements into metals and non metal. The concept of metalloids came in later

The elements posses stable electronic configuration are called as __________.

chemistry classification of elements- the periodic table introduction to periodic table necessity of classification need for classification

  1. Transition metals

  2. Non-transition metals

  3. Noble gases

  4. None of these

Show answer
Correct Option: C
Explanation:

Noble gases have stable configuration of $ns^2 np^6$ with their octet completely filled which, gives them stability. Helium has exception.

According to classification of elements most of non-metals are placed in ________ block.

chemistry classification of elements- the periodic table introduction to periodic table necessity of classification need for classification

  1. $s$ - block

  2. $p$ - block

  3. $d$ - block

  4. $f$ - block

Show answer
Correct Option: B
Explanation:

The $p$ - block is the area of the periodic table containing columns $3A$ to column $8A$ (columns$ 13-18$), including noble gas, all non metals, metals and metalloids. 

After the classification of elements study of elements become____________.

chemistry classification of elements- the periodic table introduction to periodic table necessity of classification need for classification

  1. difficult

  2. easy

  3. both A and B

  4. None of these

Show answer
Correct Option: B
Explanation:

 Elements with similar chemical properties generally fall into the same group in the periodic table, and the elements in the same period tend to have similar properties.Thus, it is relatively easy to predict the chemical properties of an element if one knows the properties of the elements around it.

Classification of elements are done on the basis of ___________.

chemistry classification of elements- the periodic table introduction to periodic table necessity of classification need for classification

  1. atomic number

  2. atomic weight

  3. valency

  4. none of these

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Correct Option: A
Explanation:

Based on the modern periodic law, the elements are arranged into rows and columns based on their atomic number. There are 18 columns, called groups and 7 rows, called periods. 

The physical properties of elements changes according to_____________.

chemistry classification of elements- the periodic table introduction to periodic table necessity of classification need for classification

  1. classification of elements in groups and periods

  2. classification of elements in groups

  3. classification of elements in periods

  4. None of these

Show answer
Correct Option: A
Explanation:

The physical properties (notably, melting and boiling points) of the elements in a given trend in vary from group to group and from period to period.


Hence the correct option is A.