11
Na
Sodium
22.99
Sodium
Alkali metal
Sodium is element 11, symbol Na. It sits in period 3, group 1, and weighs 22.99.
They give up their single outer electron so readily that water sets them off.
- Atomic number
- 11
- Atomic weight
- 22.99
- Period
- Period 3
- Group
- Group 1
- Block
- s block
- Electron configuration
- [Ne] 3s1
- Outer-shell electrons
- 1
- Neutrons
- 12
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 Sodium's number and symbol?
Element 11, symbol Na, atomic weight 22.99.
Q. Where does it sit in the table?
Period 3, group 1 — a alkali metal.
Q. What is its electron configuration?
1s2 2s2 2p6 3s1, or [Ne] 3s1 for short.
Q. How many neutrons does it have?
Rounding the atomic weight and subtracting the atomic number gives 12. The exact count depends on the isotope.