Classification of Elements and Periodicity in Properties
89565
What will be the order of Ist ionisation energy?
1 Li $>\mathrm{Na}>\mathrm{K}$
2 $\mathrm{K}>\mathrm{Li}<\mathrm{Na}$
3 $\mathrm{Na}>\mathrm{Li}>\mathrm{K}$
4 $\mathrm{Li}>\mathrm{K}>\mathrm{Na}$
Explanation:
On moving from top to bottom in a group ionisation energy decreases because atomic size increases and due to lessening of the nucleus by inner electrons. This means that $\mathrm{Li}$ will be having highest ionisation energy and $\mathrm{K}$ will be having the lowest energy. So, the ionisation energy of $\mathrm{Li}, \mathrm{Na}$ and $\mathrm{K}$ are 520 $\mathrm{kJ} / \mathrm{mole}, 496 \mathrm{~kJ} / \mathrm{mole}$ and $419 \mathrm{~kJ} / \mathrm{mole}$ respectively.
JIPMER-2006
Classification of Elements and Periodicity in Properties
89566
Generally, the first ionization energy increases along a period. But there are some exceptions. One which is not an exception is
1 $\mathrm{N}$ and $\mathrm{O}$
2 $\mathrm{Na}$ and $\mathrm{Mg}$
3 $\mathrm{Mg}$ and $\mathrm{Al}$
4 $\mathrm{Be}$ and $\mathrm{B}$
Explanation:
Na belongs to IA group and $\mathrm{Mg}$ belongs to IIA group. On moving form left to right in a period, first ionization energy increases, thus, IE of $\mathrm{Mg}$ is greater than the IE of $\mathrm{Na}$. IE order $\mathrm{Mg}>\mathrm{Na}$
2010
Classification of Elements and Periodicity in Properties
89573
Four successive members of the first row transition elements are listed below with their atomic numbers. Which one of them is expected to have the highest third ionisation enthalpy?
1 Vanadium $(\mathrm{Z}=23)$
2 Manganese $(Z=25)$
3 Chromium $(\mathrm{Z}=24)$
4 $\operatorname{Iron}(\mathrm{Z}=26)$
Explanation:
The electronic configuration of $\mathrm{Mn}$ is${ }_{25} \mathrm{Mn}=1 \mathrm{~s}^2, 2 \mathrm{~s}^2, 2 \mathrm{p}^6, 3 \mathrm{~s}^2, 3 \mathrm{p}^6, 4 \mathrm{~s}^2, 3 \mathrm{~d}^5$ Third electron which is removed in third ionization potential belong to $3 \mathrm{~d}^5$ subshell. The $3 \mathrm{~d}^5$ subshell has highest stability because of it is a half-filled subshell so, Mn shows highest third ionization potential.
NEET-2005
Classification of Elements and Periodicity in Properties
89575
Which element has maximum first ionisation potential?
1 $\mathrm{Cs}$
2 $\mathrm{F}$
3 $\mathrm{Na}$
4 $\mathrm{He}$
Explanation:
On moving from left to right in a period generally ionisation energy increases helium (He) is stable configuration is remove one electron from filled $\mathrm{s}$-subshell. The required is more due to filled $1 \mathrm{~s}$ orbital. Hence, the first ionisaiton energy is maximum in $\mathrm{He}$.
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Classification of Elements and Periodicity in Properties
89565
What will be the order of Ist ionisation energy?
1 Li $>\mathrm{Na}>\mathrm{K}$
2 $\mathrm{K}>\mathrm{Li}<\mathrm{Na}$
3 $\mathrm{Na}>\mathrm{Li}>\mathrm{K}$
4 $\mathrm{Li}>\mathrm{K}>\mathrm{Na}$
Explanation:
On moving from top to bottom in a group ionisation energy decreases because atomic size increases and due to lessening of the nucleus by inner electrons. This means that $\mathrm{Li}$ will be having highest ionisation energy and $\mathrm{K}$ will be having the lowest energy. So, the ionisation energy of $\mathrm{Li}, \mathrm{Na}$ and $\mathrm{K}$ are 520 $\mathrm{kJ} / \mathrm{mole}, 496 \mathrm{~kJ} / \mathrm{mole}$ and $419 \mathrm{~kJ} / \mathrm{mole}$ respectively.
JIPMER-2006
Classification of Elements and Periodicity in Properties
89566
Generally, the first ionization energy increases along a period. But there are some exceptions. One which is not an exception is
1 $\mathrm{N}$ and $\mathrm{O}$
2 $\mathrm{Na}$ and $\mathrm{Mg}$
3 $\mathrm{Mg}$ and $\mathrm{Al}$
4 $\mathrm{Be}$ and $\mathrm{B}$
Explanation:
Na belongs to IA group and $\mathrm{Mg}$ belongs to IIA group. On moving form left to right in a period, first ionization energy increases, thus, IE of $\mathrm{Mg}$ is greater than the IE of $\mathrm{Na}$. IE order $\mathrm{Mg}>\mathrm{Na}$
2010
Classification of Elements and Periodicity in Properties
89573
Four successive members of the first row transition elements are listed below with their atomic numbers. Which one of them is expected to have the highest third ionisation enthalpy?
1 Vanadium $(\mathrm{Z}=23)$
2 Manganese $(Z=25)$
3 Chromium $(\mathrm{Z}=24)$
4 $\operatorname{Iron}(\mathrm{Z}=26)$
Explanation:
The electronic configuration of $\mathrm{Mn}$ is${ }_{25} \mathrm{Mn}=1 \mathrm{~s}^2, 2 \mathrm{~s}^2, 2 \mathrm{p}^6, 3 \mathrm{~s}^2, 3 \mathrm{p}^6, 4 \mathrm{~s}^2, 3 \mathrm{~d}^5$ Third electron which is removed in third ionization potential belong to $3 \mathrm{~d}^5$ subshell. The $3 \mathrm{~d}^5$ subshell has highest stability because of it is a half-filled subshell so, Mn shows highest third ionization potential.
NEET-2005
Classification of Elements and Periodicity in Properties
89575
Which element has maximum first ionisation potential?
1 $\mathrm{Cs}$
2 $\mathrm{F}$
3 $\mathrm{Na}$
4 $\mathrm{He}$
Explanation:
On moving from left to right in a period generally ionisation energy increases helium (He) is stable configuration is remove one electron from filled $\mathrm{s}$-subshell. The required is more due to filled $1 \mathrm{~s}$ orbital. Hence, the first ionisaiton energy is maximum in $\mathrm{He}$.
Classification of Elements and Periodicity in Properties
89565
What will be the order of Ist ionisation energy?
1 Li $>\mathrm{Na}>\mathrm{K}$
2 $\mathrm{K}>\mathrm{Li}<\mathrm{Na}$
3 $\mathrm{Na}>\mathrm{Li}>\mathrm{K}$
4 $\mathrm{Li}>\mathrm{K}>\mathrm{Na}$
Explanation:
On moving from top to bottom in a group ionisation energy decreases because atomic size increases and due to lessening of the nucleus by inner electrons. This means that $\mathrm{Li}$ will be having highest ionisation energy and $\mathrm{K}$ will be having the lowest energy. So, the ionisation energy of $\mathrm{Li}, \mathrm{Na}$ and $\mathrm{K}$ are 520 $\mathrm{kJ} / \mathrm{mole}, 496 \mathrm{~kJ} / \mathrm{mole}$ and $419 \mathrm{~kJ} / \mathrm{mole}$ respectively.
JIPMER-2006
Classification of Elements and Periodicity in Properties
89566
Generally, the first ionization energy increases along a period. But there are some exceptions. One which is not an exception is
1 $\mathrm{N}$ and $\mathrm{O}$
2 $\mathrm{Na}$ and $\mathrm{Mg}$
3 $\mathrm{Mg}$ and $\mathrm{Al}$
4 $\mathrm{Be}$ and $\mathrm{B}$
Explanation:
Na belongs to IA group and $\mathrm{Mg}$ belongs to IIA group. On moving form left to right in a period, first ionization energy increases, thus, IE of $\mathrm{Mg}$ is greater than the IE of $\mathrm{Na}$. IE order $\mathrm{Mg}>\mathrm{Na}$
2010
Classification of Elements and Periodicity in Properties
89573
Four successive members of the first row transition elements are listed below with their atomic numbers. Which one of them is expected to have the highest third ionisation enthalpy?
1 Vanadium $(\mathrm{Z}=23)$
2 Manganese $(Z=25)$
3 Chromium $(\mathrm{Z}=24)$
4 $\operatorname{Iron}(\mathrm{Z}=26)$
Explanation:
The electronic configuration of $\mathrm{Mn}$ is${ }_{25} \mathrm{Mn}=1 \mathrm{~s}^2, 2 \mathrm{~s}^2, 2 \mathrm{p}^6, 3 \mathrm{~s}^2, 3 \mathrm{p}^6, 4 \mathrm{~s}^2, 3 \mathrm{~d}^5$ Third electron which is removed in third ionization potential belong to $3 \mathrm{~d}^5$ subshell. The $3 \mathrm{~d}^5$ subshell has highest stability because of it is a half-filled subshell so, Mn shows highest third ionization potential.
NEET-2005
Classification of Elements and Periodicity in Properties
89575
Which element has maximum first ionisation potential?
1 $\mathrm{Cs}$
2 $\mathrm{F}$
3 $\mathrm{Na}$
4 $\mathrm{He}$
Explanation:
On moving from left to right in a period generally ionisation energy increases helium (He) is stable configuration is remove one electron from filled $\mathrm{s}$-subshell. The required is more due to filled $1 \mathrm{~s}$ orbital. Hence, the first ionisaiton energy is maximum in $\mathrm{He}$.
Classification of Elements and Periodicity in Properties
89565
What will be the order of Ist ionisation energy?
1 Li $>\mathrm{Na}>\mathrm{K}$
2 $\mathrm{K}>\mathrm{Li}<\mathrm{Na}$
3 $\mathrm{Na}>\mathrm{Li}>\mathrm{K}$
4 $\mathrm{Li}>\mathrm{K}>\mathrm{Na}$
Explanation:
On moving from top to bottom in a group ionisation energy decreases because atomic size increases and due to lessening of the nucleus by inner electrons. This means that $\mathrm{Li}$ will be having highest ionisation energy and $\mathrm{K}$ will be having the lowest energy. So, the ionisation energy of $\mathrm{Li}, \mathrm{Na}$ and $\mathrm{K}$ are 520 $\mathrm{kJ} / \mathrm{mole}, 496 \mathrm{~kJ} / \mathrm{mole}$ and $419 \mathrm{~kJ} / \mathrm{mole}$ respectively.
JIPMER-2006
Classification of Elements and Periodicity in Properties
89566
Generally, the first ionization energy increases along a period. But there are some exceptions. One which is not an exception is
1 $\mathrm{N}$ and $\mathrm{O}$
2 $\mathrm{Na}$ and $\mathrm{Mg}$
3 $\mathrm{Mg}$ and $\mathrm{Al}$
4 $\mathrm{Be}$ and $\mathrm{B}$
Explanation:
Na belongs to IA group and $\mathrm{Mg}$ belongs to IIA group. On moving form left to right in a period, first ionization energy increases, thus, IE of $\mathrm{Mg}$ is greater than the IE of $\mathrm{Na}$. IE order $\mathrm{Mg}>\mathrm{Na}$
2010
Classification of Elements and Periodicity in Properties
89573
Four successive members of the first row transition elements are listed below with their atomic numbers. Which one of them is expected to have the highest third ionisation enthalpy?
1 Vanadium $(\mathrm{Z}=23)$
2 Manganese $(Z=25)$
3 Chromium $(\mathrm{Z}=24)$
4 $\operatorname{Iron}(\mathrm{Z}=26)$
Explanation:
The electronic configuration of $\mathrm{Mn}$ is${ }_{25} \mathrm{Mn}=1 \mathrm{~s}^2, 2 \mathrm{~s}^2, 2 \mathrm{p}^6, 3 \mathrm{~s}^2, 3 \mathrm{p}^6, 4 \mathrm{~s}^2, 3 \mathrm{~d}^5$ Third electron which is removed in third ionization potential belong to $3 \mathrm{~d}^5$ subshell. The $3 \mathrm{~d}^5$ subshell has highest stability because of it is a half-filled subshell so, Mn shows highest third ionization potential.
NEET-2005
Classification of Elements and Periodicity in Properties
89575
Which element has maximum first ionisation potential?
1 $\mathrm{Cs}$
2 $\mathrm{F}$
3 $\mathrm{Na}$
4 $\mathrm{He}$
Explanation:
On moving from left to right in a period generally ionisation energy increases helium (He) is stable configuration is remove one electron from filled $\mathrm{s}$-subshell. The required is more due to filled $1 \mathrm{~s}$ orbital. Hence, the first ionisaiton energy is maximum in $\mathrm{He}$.