name:
teacher:
q2 chemistry: u3l7 successive ionization energy date:
prepwork: successive ionization energy practice
1. **which atom has a higher second ionization energy? beryllium or lithium? why?
2. circle the element in each of the following sets would you expect to have the lowest third ionization energy, ie₃? briefly explain your reasoning.
a. **na, mg, al
reasoning:
b. *k, ca, sc
reasoning:
c. li, al, b
reasoning:

Question

Accepted Answer

### 1. Which atom has a higher second ionization energy? Beryllium or lithium? Why?
# Brief Explanations:
Lithium ($Li$) has the electron configuration $1s^{2}2s^{1}$. After losing one electron (first ionization), it has the stable $1s^{2}$ (helium - like) configuration. Removing a second electron from this stable configuration requires a large amount of energy. Beryllium ($Be$) has the electron configuration $1s^{2}2s^{2}$. After the first ionization ($Be^{+}:1s^{2}2s^{1}$), the second ionization is removing an electron from the $2s$ orbital, but it is not as stable as the noble - gas configuration of $Li^{+}$ after first ionization.
# Answer:
Lithium has a higher second ionization energy. Because after the first ionization, $Li^{+}$ has a stable noble - gas ($He$ - like) configuration ($1s^{2}$), and removing a second electron from this very stable configuration requires more energy compared to $Be^{+}$ ($Be^{+}$ has the configuration $1s^{2}2s^{1}$ after first ionization).

### 2.
#### a. $Na$, $Mg$, $Al$
# Brief Explanations:
Sodium ($Na$) has the electron configuration $[Ne]3s^{1}$. After two ionizations ($Na^{2 +}:[Ne]$), the third ionization is removing an electron from the stable $Ne$ - like core. Magnesium ($Mg$) has $[Ne]3s^{2}$. After two ionizations ($Mg^{2+}:[Ne]$),  the third ionization is also from the stable core. Aluminium ($Al$) has $[Ne]3s^{2}3p^{1}$. After two ionizations ($Al^{2+}:[Ne]3s^{1}$), the third ionization is removing an electron from the $3s$ orbital (less stable than the core for $Na^{2+}$ and $Mg^{2+}$).
# Answer:
$Al$ has the lowest third ionization energy. $Al^{2+}$ has the electron configuration $[Ne]3s^{1}$, and removing the $3s$ electron is easier compared to removing an electron from the stable $Ne$ - like core ($[Ne]$) for $Na^{2+}$ and $Mg^{2+}$.

#### b. $K$, $Ca$, $Sc$
# Brief Explanations:
Potassium ($K$) has $[Ar]4s^{1}$. After two ionizations ($K^{2+}:[Ar]$), third ionization is from the stable core. Calcium ($Ca$) has $[Ar]4s^{2}$. After two ionizations ($Ca^{2+}:[Ar]$), third ionization is from the stable core. Scandium ($Sc$) has $[Ar]3d^{1}4s^{2}$. After two ionizations ($Sc^{2+}:[Ar]3d^{1}$), the third ionization is removing a $3d$ electron (less tightly bound than the core electrons for $K^{2+}$ and $Ca^{2+}$ as $3d$ has a higher energy and is more shielded in the multi - electron atom).
# Answer:
$Sc$ has the lowest third ionization energy. $Sc^{2+}$ has the electron configuration $[Ar]3d^{1}$, and the $3d$ electron is less tightly bound (due to higher energy and shielding) compared to the electrons in the stable $Ar$ - like core for $K^{2+}$ and $Ca^{2+}$.

#### c. $Li$, $Al$, $B$
# Brief Explanations:
Lithium ($Li$) has $[He]2s^{1}$. After two ionizations ($Li^{2+}:[He]$), third ionization is from the stable core. Aluminium ($Al$) has $[Ne]3s^{2}3p^{1}$. After two ionizations ($Al^{2+}:[Ne]3s^{1}$), third ionization is from $3s$. Boron ($B$) has $[He]2s^{2}2p^{1}$. After two ionizations ($B^{2+}:[He]2s^{1}$), the third ionization is removing a $2s$ electron. The $2s$ orbital in $B^{2+}$ is lower in energy (more tightly bound) than the $3s$ orbital in $Al^{2+}$ (due to the smaller principal quantum number $n = 2$ compared to $n=3$ for $Al^{2+}$'s $3s$ electron).
# Answer:
$Al$ has the lowest third ionization energy. $Al^{2+}$ has the electron configuration $[Ne]3s^{1}$, and the $3s$ electron is less tightly bound (higher $n$ value, more shielded) compared to the $2s$ electron in $B^{2+}$ ($B^{2+}:[He]2s^{1}$) and the electron in the stable core ($[He]$) for $Li^{2+}$.

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QUESTION IMAGE

Question

Explanation:

1. Which atom has a higher second ionization energy? Beryllium or lithium? Why?

Answer:

2.

a. \(Na\), \(Mg\), \(Al\)