8
O
Oxygen
15.999
Oxygen
Nonmetal
Oxygen is element 8, symbol O. It sits in period 2, group 16, and weighs 15.999.
Poor conductors that tend to take on electrons and become negative ions.
- Atomic number
- 8
- Atomic weight
- 15.999
- Period
- Period 2
- Group
- Group 16
- Block
- p block
- Electron configuration
- [He] 2s2 2p4
- Outer-shell electrons
- 6
- Neutrons
- 8
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 Oxygen's number and symbol?
Element 8, symbol O, atomic weight 15.999.
Q. Where does it sit in the table?
Period 2, group 16 — a nonmetal.
Q. What is its electron configuration?
1s2 2s2 2p4, or [He] 2s2 2p4 for short.
Q. How many neutrons does it have?
Rounding the atomic weight and subtracting the atomic number gives 8. The exact count depends on the isotope.