78
Pt
Platinum
195.08
Platinum
Transition metal
Platinum is element 78, symbol Pt. It sits in period 6, group 10, and weighs 195.08.
Metals filling an inner shell as they go, giving several oxidation states and colour.
- Atomic number
- 78
- Atomic weight
- 195.08
- Period
- Period 6
- Group
- Group 10
- Block
- d block
- Electron configuration
- [Xe] 6s2 4f14 5d8
- Neutrons
- 117
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 Platinum's number and symbol?
Element 78, symbol Pt, atomic weight 195.08.
Q. Where does it sit in the table?
Period 6, group 10 — a transition metal.
Q. What is its electron configuration?
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d8, or [Xe] 6s2 4f14 5d8 for short.
Q. How many neutrons does it have?
Rounding the atomic weight and subtracting the atomic number gives 117. The exact count depends on the isotope.