To determine the noble-gas notation electron configuration for Calcium (Ca) and Promethium (Pm), let's break it down step by step.
### Calcium (Ca)
1. Identify the Atomic Number:
- Calcium has an atomic number of 20, meaning it has 20 electrons.
2. Identify the Noble Gas Preceding Calcium:
- The noble gas preceding Calcium in the periodic table is Argon (Ar), which has an atomic number of 18. This means that Argon has 18 electrons.
3. Electron Configuration for Argon (Ar):
- The full electron configuration for Argon is: [tex]\(1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^6\)[/tex].
4. Continue the Electron Configuration Beyond Argon:
- Since Argon has 18 electrons, Calcium needs 2 more electrons to reach 20. These additional electrons will go into the next available orbitals.
- The next available orbital is the 4s orbital.
5. Write the Final Electron Configuration for Calcium:
- The electron configuration for Calcium, incorporating the noble gas notation, is: [tex]\([Ar] 4s^2\)[/tex].
### Promethium (Pm)
1. Identify the Atomic Number:
- Promethium has an atomic number of 61, meaning it has 61 electrons.
2. Identify the Noble Gas Preceding Promethium:
- The noble gas preceding Promethium in the periodic table is Xenon (Xe), which has an atomic number of 54. This means that Xenon has 54 electrons.
3. Electron Configuration for Xenon (Xe):
- The full electron configuration for Xenon is: [tex]\(1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^6\ 4s^2\ 3d^{10}\ 4p^6\ 5s^2\ 4d^{10}\ 5p^6\)[/tex].
4. Continue the Electron Configuration Beyond Xenon:
- Since Xenon has 54 electrons, Promethium needs 7 more electrons to reach 61. These additional electrons will go into the next available orbitals.
- Following Xenon, the next available orbitals are in the 4f and 6s orbitals.
- The first 2 electrons go into the 6s orbital.
- The following 5 electrons go into the 4f orbital.
5. Write the Final Electron Configuration for Promethium:
- The electron configuration for Promethium, incorporating the noble gas notation, is: [tex]\([Xe] 4f^5\ 6s^2\)[/tex].
Hence, the noble-gas notation electron configurations are:
- [tex]\( \text{Ca:} \ [Ar] 4s^2 \)[/tex]
- [tex]\( \text{Pm:} \ [Xe] 4f^5 6s^2 \)[/tex]
