راديوم (Ra)
راديوم is the chemical element with atomic number 88 and symbol Ra. It is a فلز قلوي ترابي in period 7, group 2, with a standard atomic weight of 226 u.
حقائق أساسية
- Z
- 88
- Atomic weight
- 226 u no stable isotope
- Category
- فلز قلوي ترابي
- State at 298 K
- Solid
- Occurrence
- from decay, radioactive
- Discovered
- 1898
- CAS
- 7440-14-4
الخصائص المقيسة
| Property | Value | Source |
|---|---|---|
| Electronegativity | 0.9 | National Center for Biotechnology Information (NIH) |
| Melting point | 973 K | National Center for Biotechnology Information (NIH) |
| Boiling point | 1,413 K | National Center for Biotechnology Information (NIH) |
| Density stp | 5 g/cm³ | National Center for Biotechnology Information (NIH) |
| Atomic radius empirical | 283 pm | National Center for Biotechnology Information (NIH) |
| Ionization energy 1st | 509.3 kJ/mol | National Center for Biotechnology Information (NIH) |
التوزيع الإلكتروني
- Noble gas notation
- [Rn] 7s²
- Full notation
- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶ 7s²
- Electrons per shell
- 2, 8, 18, 32, 18, 8, 2