Let's identify the elements based on their electron configurations:
1. Configuration: [tex]$[He] 2s^2$[/tex]
- This configuration indicates that the element has completed the electron configuration up to Helium (which has 2 electrons) and has an additional 2 electrons in the 2s orbital.
- This makes the total electron count as [tex]$2 (\text{from Helium}) + 2 (\text{from } 2s^2) = 4$[/tex] electrons.
- The element with 4 electrons is Beryllium (Be).
2. Configuration: [tex]$[Ne] 3s^2 3p^5$[/tex]
- This configuration shows that the element has completed the electron configuration up to Neon (which has 10 electrons) and has additional electrons in the 3s and 3p orbitals.
- Adding these electrons gives us: [tex]$10 (\text{from Neon}) + 2 (\text{from } 3s^2) + 5 (\text{from } 3p^5) = 17$[/tex] electrons.
- The element with 17 electrons is Chlorine (Cl).
3. Configuration: [tex]$[Xe] 6s^2$[/tex]
- This configuration indicates that the element has completed the electron configuration up to Xenon (which has 54 electrons) and has an additional 2 electrons in the 6s orbital.
- Thus, the total electron count is [tex]$54 (\text{from Xenon}) + 2 (\text{from } 6s^2) = 56$[/tex] electrons.
- The element with 56 electrons is Barium (Ba).
4. Configuration: [tex]$[\operatorname{Ar}] 4s^2 3d^9$[/tex]
- This configuration shows that the element has completed the electron configuration up to Argon (which has 18 electrons) and has additional electrons in the 4s and 3d orbitals.
- Adding these electrons gives us: [tex]$18 (\text{from Argon}) + 2 (\text{from } 4s^2) + 9 (\text{from } 3d^9) = 29$[/tex] electrons.
- The element with 29 electrons is Copper (Cu).
So the elements corresponding to the given electron configurations are:
- [tex]$[He] 2s^2$[/tex]: Beryllium (Be)
- [tex]$[Ne] 3s^2 3p^5$[/tex]: Chlorine (Cl)
- [tex]$[Xe] 6s^2$[/tex]: Barium (Ba)
- [tex]$[\operatorname{Ar}] 4s^2 3d^9$[/tex]: Copper (Cu)
