13
Al
Aluminium
26.982
Aluminium
Post-transition metal
Aluminium is element 13, symbol Al. It sits in period 3, group 13, and weighs 26.982.
The metals to the right of the transition block: softer, with lower melting points.
- Atomic number
- 13
- Atomic weight
- 26.982
- Period
- Period 3
- Group
- Group 13
- Block
- p block
- Electron configuration
- [Ne] 3s2 3p1
- Outer-shell electrons
- 3
- Neutrons
- 14
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 Aluminium's number and symbol?
Element 13, symbol Al, atomic weight 26.982.
Q. Where does it sit in the table?
Period 3, group 13 — a post-transition metal.
Q. What is its electron configuration?
1s2 2s2 2p6 3s2 3p1, or [Ne] 3s2 3p1 for short.
Q. How many neutrons does it have?
Rounding the atomic weight and subtracting the atomic number gives 14. The exact count depends on the isotope.