Astatine Valence Electrons
Why astatine has 7
Astatine has 85 electrons, arranged as 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p5. The highest shell is n = 6, holding 6s2 6p5, so 2 + 5 = 7.
Astatine is in group 17; for groups 13–18 subtract 10 from the group number.
What that means for bonding
Astatine needs 1 more electron to complete an octet, so it tends to gain one (forming At−) or share one in a single covalent bond.
Electrons per shell: 2, 8, 18, 32, 18, 7. See the astatine electron configuration and orbital diagram or the full astatine data sheet.
Same group, same count
Astatine valence electrons FAQ
How many valence electrons does astatine have?
Astatine has 7 valence electrons. Its electron configuration is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁵, and the outermost shell (n = 6) holds 6s² + 6p⁵.
How do you find the valence electrons of astatine?
Astatine is in group 17; for groups 13–18 subtract 10 from the group number.
How many bonds does astatine form?
Astatine needs 1 more electron to complete an octet, so it tends to gain one (forming At−) or share one in a single covalent bond.
What is the Lewis dot structure of astatine?
The symbol At with 7 dots around it, one per valence electron, placed singly on each side before any side is paired.
How many core electrons does astatine have?
78: 85 electrons in total minus the 7 valence electrons.