86
Rn
Radon
222
Radon
Noble gas
Radon is element 86, symbol Rn. It sits in period 6, group 18, and weighs 222.
Their outer shell is already full, so they barely react with anything.
- Atomic number
- 86
- Atomic weight
- 222
- Period
- Period 6
- Group
- Group 18
- Block
- p block
- Electron configuration
- [Xe] 6s2 4f14 5d10 6p6
- Outer-shell electrons
- 8
- Neutrons
- 136
The periodic table
Rows are periods, columns are groups. Tap any square to open that element.
1H2He3Li4Be5B6C7N8O9F10Ne11Na12Mg13Al14Si15P16S17Cl18Ar19K20Ca21Sc22Ti23V24Cr25Mn26Fe27Co28Ni29Cu30Zn31Ga32Ge33As34Se35Br36Kr37Rb38Sr39Y40Zr41Nb42Mo43Tc44Ru45Rh46Pd47Ag48Cd49In50Sn51Sb52Te53I54Xe55Cs56Ba57La58Ce59Pr60Nd61Pm62Sm63Eu64Gd65Tb66Dy67Ho68Er69Tm70Yb71Lu72Hf73Ta74W75Re76Os77Ir78Pt79Au80Hg81Tl82Pb83Bi84Po85At86Rn87Fr88Ra89Ac90Th91Pa92U93Np94Pu95Am96Cm97Bk98Cf99Es100Fm101Md102No103Lr104Rf105Db106Sg107Bh108Hs109Mt110Ds111Rg112Cn113Nh114Fl115Mc116Lv117Ts118Og
Others in the same group
Neighbours by number
How to read this
- A row (period) is the number of electron shells. Elements in period 3 carry three of them.
- A column (group) tells you how many electrons sit in the outer shell — which is why a group behaves alike.
- Atomic weight runs at roughly twice the atomic number: about as many neutrons as protons.
- The 28 lanthanides and actinides are drawn below the table. Slotting them in would stretch it to 32 columns.
Frequently asked questions
Q. What are Radon's number and symbol?
Element 86, symbol Rn, atomic weight 222.
Q. Where does it sit in the table?
Period 6, group 18 — a noble gas.
Q. What is its electron configuration?
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6, or [Xe] 6s2 4f14 5d10 6p6 for short.
Q. How many neutrons does it have?
Rounding the atomic weight and subtracting the atomic number gives 136. The exact count depends on the isotope.