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Tin (Sn)

Tin is the 50th element, a post-transition metal in the p-block. Its standard atomic weight is 118.711.

Period 5Group 14p-blockPost-transition metal
50Sn

Tin

118.711

What the table records

Atomic number
50
Standard atomic weight
118.711
Group
14
Period
5
Block
p-block
Category
Post-transition metal
Electron configuration
[Kr] 4d10 5s2 5p2
Valence electrons
4
Typical valence
2
Van der Waals radius
2.25 Å
Covalent radius
1.39 Å

The configuration above is the aufbau order.

How to read these numbers

The standard atomic weight is an average over the isotopes as they occur naturally, which is why it is rarely a whole number. It is the figure a molar mass calculation uses. Work in mass spectrometry wants the monoisotopic mass of a single isotope instead, which is a different number.

The two radii are not the same measurement. The covalent radius is half the distance between two bonded atoms of the element; the van der Waals radius is how close a non-bonded atom gets before repulsion takes over, and is always the larger. Space-filling models are drawn with the second, ball-and-stick models with the first — which is why the same molecule looks so different in the two.