Nuklida · radioaktif · alami
Kalium-40 (⁴⁰K)
Kalium-40 (⁴⁰K) adalah isotop radioaktif kalium dengan 19 proton dan 21 neutron (nomor massa 40). Waktu paruhnya 1,248 miliar tahun (± 0,003 miliar tahun), meluruh terutama lewat peluruhan beta minus (β⁻). Kelimpahan alaminya 0.000 117(1).
Data nuklida
- Unsur
- Kalium (K, Z = 19)
- Nomor massa (A)
- 40
- Proton (Z)
- 19
- Neutron (N)
- 21
- Massa atom
- 39.963998165 ± 0.00000006 u
- Waktu paruh
- 1,248 miliar tahun (± 0,003 miliar tahun)
- Mode peluruhan
- Peluruhan beta minus (β⁻) ( 89,28 %), Peluruhan beta plus (β⁺) ( 10,72 %)
- Inti anak
- Kalsium-40 (⁴⁰Ca), Argon-40 (⁴⁰Ar)
- Kelimpahan alami
- 0.000 117(1)
- Tahun penemuan
- 1935
- Sumber data
- IAEA Atomic Mass Data Center (NUBASE) and IUPAC CIAAW, via PubChem
Kegunaan isotop kalium
- The mole fraction of 40K, n(40K)/n(K), is used to study the effects of potassium in soil on the growth of plants. Plants need potassium to promote growth and reproduction, and potassium also helps plants resist drought and diseases. The mole fraction of 40K is being studied at different depths in several soil types to determine how soil properties affect the fractionation of 40K.
- The amount ratio n(40K)/n(40Ar) is used in potassium-argon dating by geologists, archaeologists, and paleoanthropologists to determine the age of rocks. This dating method is based on the radioactive decay of 40K, having a half-life of 1.248×109 years, to 40Ar. When lava crystalizes, 40Ar can no longer escape and begins increasing in concentration in a rock (Fig. IUPAC.19.1),.
Reaksi inti
Isotop kalium lainnya
³¹K, ³²K, ³³K, ³⁴K, ³⁵K, ³⁶K, ³⁷K, ³⁸K, ³⁹K, ⁴¹K, ⁴²K, ⁴³K, ⁴⁴K, ⁴⁵K, ⁴⁶K, ⁴⁷K, ⁴⁸K, ⁴⁹K, ⁵⁰K, ⁵¹K, ⁵²K, ⁵³K, ⁵⁴K, ⁵⁵K, ⁵⁶K, ⁵⁷K, ⁵⁸K, ⁵⁹K