Question

e) Iodine
1. Write the complete electron configuration.
2. What is the valence shell? 3. How many valence electrons are there? 4. How many electrons between the nucleus and valence shell are there? 5. What is the noble gas configuration for this atom?

Answer 1

Certainly! Let's go through the information about iodine (I), which has an atomic number of 53.

### 1. Complete Electron Configuration
Iodine has a total of 53 electrons. The complete electron configuration is:

\[
\text{I: } 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^5
\]

### 2. Valence Shell
The valence shell is the outermost shell of an atom that contains electrons. For iodine, the valence shell is the 4th shell (n=4).

### 3. Valence Electrons
To find the number of valence electrons for iodine, we look at the electrons in the outermost shell (4s and 4p in this case):

- 4s has 2 electrons
- 4p has 5 electrons

Thus, iodine has a total of \(2 + 5 = 7\) valence electrons.

### 4. Electrons Between the Nucleus and Valence Shell
To determine the number of electrons between the nucleus and the valence shell, we count the electrons in the inner shells:

- 1st shell (n=1): 2 electrons (1s)
- 2nd shell (n=2): 8 electrons (2s and 2p)
- 3rd shell (n=3): 18 electrons (3s, 3p, and 3d)

So, the total number of inner shell electrons is \(2 + 8 + 18 = 28\) electrons.

### 5. Noble Gas Configuration
The noble gas configuration for iodine can be represented by using the nearest noble gas that precedes it, which is krypton (Kr, atomic number 36). The noble gas configuration for iodine is:

\[
\text{[Kr]} 4s^2 4p^5
\]

### Summary:
1. Complete Electron Configuration: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^5\)
2. Valence Shell: n=4
3. Valence Electrons: 7
4. Electrons Between Nucleus and Valence Shell: 28
5. Noble Gas Configuration: \([Kr] 4s^2 4p^5\)