Q: Why is Hydrogen placed in group \$I\$ of the modern periodic table ?

Hydrogen is placed in group \$I\$ of the modern periodic table due to following reasons:-\$(1)\$ It shows outer electronic configuration similar to group \$I\$ elements (i.e.\$1s^{1}\$).\$(2)\$ It readily looses its electron to form \$H^{+}\$ ion which resembles the electropositive character of group \$I\$ elements.\$(3)\$ It shows \$+1\$ oxidation state like alkali i.e. group \$I\$ elements.\$(4)\$ Hydrogen also acts as a strong reducing agent like alkali metals and also forms binary compounds with electronegative elements which resembles the group \$I\$ elements.

Q: Hydrogen occupies a unique position in Modern Periodic Table.

Hydrogen has electron configuration of \$ 1s^{1}\$.To become stable it can either accept to get helium configuration that is a stable configuration or it can even donate one electron. Hence it is very confusing where to place either in the metals group as it donates or in nonmetal group as it accepts an electron. Hence it occupies a unique position in the periodic table.

Q: Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.

Hydrogen with atomic number 1 and electronic configuration \$1s^1\$ is the first element in the periodic table. It resembles alkali metals as well as halogens. Hence, its position is anomalous. Some chemists argue that hydrogen should be placed along with alkali metals whereas other chemist argue that hydrogen should be placed with halogens.

Q: Among \$NH_3\$, \$H_2O\$ and \$HF\$, which would you expect to have highest magnitude of hydrogen bonding and why?

The electronegativity of \$N, O\$ and \$F\$ is much higher than the electronegativity of \$H\$. Hence, \$\displaystyle NH_3, H_2O \$ and \$ HF \$ forms hydrogen bonds. \$F\$ is most electronegative and the magnitude of negative charge on \$F\$ and positive charge on \$H\$ is highest and thus, the \$H\$ bonding is strongest in \$HF\$.

Question 1

Why is Hydrogen placed in group $I$ of the modern periodic table ?

Accepted Answer

Hydrogen is placed in group $I$ of the modern periodic table due to following reasons:-$(1)$ It shows outer electronic configuration similar to group $I$ elements (i.e.$1s^{1}$).$(2)$ It readily looses its electron to form $H^{+}$ ion which resembles the electropositive character of group $I$ elements.$(3)$ It shows $+1$ oxidation state like alkali i.e. group $I$ elements.$(4)$ Hydrogen also acts as a strong reducing agent like alkali metals and also forms binary compounds with electronegative elements which resembles the group $I$ elements.

Question 2

What do you understand by (i) electron-deficient, (ii) electron-precise, and (iii) electron-rich compounds of hydrogen?

Accepted Answer

(i) Electron deficient compounds of hydrogen do not have sufficient number &#10;of electrons to form normal covalent bonds. Examples include hydrides of&#10; group 13 such as $\displaystyle BH_3, AlH_3 $ etc. They exist in &#10;polymeric forms such as $\displaystyle B_2H_6, Al_2H_6 $. Thus, they &#10;make up their deficiency.(ii) Electron precise compounds of hydrogen contain sufficient valence &#10;electrons to form covalent bonds. Examples include group 14 hydrides &#10;$\displaystyle CH_4,SiH_4, GeH_4, SnH_4, PbH_4 $ etc. These compounds &#10;have tetrahedral shape.(iii) Electron rich compounds of hydrogen contain excess valence electrons to form covalent bonds.Examples include group 15 and group 17 hydrides such as $\displaystyle NH_3, PH_3, HCl, HBr $ etc. These compounds contains lone pairs of electrons.

Question 3

Hydrogen occupies a unique position in Modern Periodic Table.

Accepted Answer

Hydrogen has electron configuration of $ 1s^{1}$.To become stable it can either accept to get helium configuration that is a stable configuration or it can even donate one electron. Hence it is very confusing where to place either in the metals group as it donates or in nonmetal group as it accepts an electron. Hence it occupies a unique position in the periodic table.

Question 4

Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.

Accepted Answer

Hydrogen with atomic number 1 and electronic configuration $1s^1$ is the first element in the periodic table. It resembles alkali metals as well as halogens. Hence, its position is anomalous. Some chemists argue that hydrogen should be placed along with alkali metals whereas other chemist argue that hydrogen should be placed with halogens.

Question 5

Among $NH_3$, $H_2O$ and $HF$, which would you expect to have highest magnitude of  hydrogen bonding and why?

Accepted Answer

The electronegativity of $N, O$ and $F$ is much higher than the electronegativity of $H$. Hence, $\displaystyle NH_3, H_2O $ and $ HF $ forms hydrogen bonds. $F$ is most electronegative and the magnitude of negative charge on $F$ and positive charge on $H$ is highest and thus, the $H$ bonding is strongest in $HF$.

Question 6

Which of the following explanation is best for not placing hydrogen with alkali metals or halogen?

Accepted Answer

The ionization energy of hydrogen is too high for group of alkali metals, but too low for halogen group.

Question 7

Hydrogen resembles halogens in many respects for which several factors are responsible. Of the following factors which one is the most important in this respect?

Accepted Answer

Hydrogen resembles halogens as it has similar tendency to gain a single electron to attain stable noble gas configuration. The electronic configuration of hydrogen is $1s^1$. It needs one more electron to attain stable electronic configuration of hellium, a noble gas. The electronic configuration of halogen is $ns^2np^5$. It needs one more &#10;electron to attain stable electronic configuration of a noble &#10;gas.

Question 8

Which of the following statement is correct regarding hydrogen?

Accepted Answer

Hydrogen has +1 oxidation state in compounds with more electronegative elements e.g. $HF$. It has -1 oxidation state in compounds with more electropositive elements like $NaH$. In the above compounds with $Na$ and $F$ show +1 and -1 oxidation state respectively.

Question 9

Write the similarities of hydrogen with alkali metals.

Accepted Answer

There are following similarities of hydrogen with alkali metals1. Electronic Configuration: The electronic configuration of hydrogen is $1s^1$ which is similar to the outmost electronic configuration of alkali metals $(ns^1)$. Som it is placed with alkali metals in group $1$2. Electropopsitive Character: Hydrogen can from unipositive ion by losing one electron like alkali metals.e.g., $H \to H^+ + e^-$$Na\to Na^+ + e^-$3. Oxidation State: Hydrogen exhibits oxidation state of $+1$ ion the compounds of hydrogen which is similar to alkali metals.4. Valency: Valency of hydrogen is $1$ like alkali metals.5. Reaction with Non-metals: Like alkali metals, hydrogen dorms binary compounds with non-metal,6. Reducing nature: Hydrogen is a good reducing agent like alkali metals.

Question 10

Is it possible for the atom of an element to have one electron, one proton or no neutron? If so, name the element.

Accepted Answer

Yes, it is true for the common, stable isotope of hydrogen (protium) which is represented as $_{1}^{1}\textrm{H}$

Revise with Concepts

Position of Hydrogen in the Periodic Table

Learn with Videos

Why is Hydrogen placed in group $I$ of the modern periodic table ?

What do you understand by (i) electron-deficient, (ii) electron-precise, and (iii) electron-rich compounds of hydrogen?

Hydrogen occupies a unique position in Modern Periodic Table.

Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.

Among $N H_{3}$ , $H_{2} O$ and $H F$ , which would you expect to have highest magnitude of hydrogen bonding and why?

Which of the following explanation is best for not placing hydrogen with alkali metals or halogen?

Hydrogen resembles halogens in many respects for which several factors are responsible. Of the following factors which one is the most important in this respect?

Which of the following statement is correct regarding hydrogen?

Write the similarities of hydrogen with alkali metals.

Is it possible for the atom of an element to have one electron, one proton or no neutron? If so, name the element.

Revise with Concepts

Position of Hydrogen in the Periodic Table

Learn with Videos

Why is Hydrogen placed in group I of the modern periodic table ?

What do you understand by (i) electron-deficient, (ii) electron-precise, and (iii) electron-rich compounds of hydrogen?

Hydrogen occupies a unique position in Modern Periodic Table.

Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.

Among NH3​, H2​O and HF, which would you expect to have highest magnitude of hydrogen bonding and why?

Which of the following explanation is best for not placing hydrogen with alkali metals or halogen?

Hydrogen resembles halogens in many respects for which several factors are responsible. Of the following factors which one is the most important in this respect?

Which of the following statement is correct regarding hydrogen?

Write the similarities of hydrogen with alkali metals.

Is it possible for the atom of an element to have one electron, one proton or no neutron? If so, name the element.

Why is Hydrogen placed in group $I$ of the modern periodic table ?

Among $N H_{3}$ , $H_{2} O$ and $H F$ , which would you expect to have highest magnitude of hydrogen bonding and why?