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Yttrium

Yttrium (Y) is a transition metal with atomic number 39 and an atomic mass of 88.906. Its electron configuration is [Kr] 4d1 5s2.

Yttrium key data

Symbol Y
Atomic number 39
Atomic mass (standard atomic weight) 88.906
Molar mass 88.906 g/mol
Protons 39
Neutrons (most abundant isotope, yttrium-89) 50
Electrons (neutral atom) 39
Category Transition metal
Period 5
Group 3
Block d-block
Noble gas notation [Kr] 4d1 5s2
Full electron configuration 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d1 5s2
Electrons per shell 2, 8, 18, 9, 2

Atomic mass: IUPAC CIAAW abridged standard atomic weights, 2024. Most abundant isotope: NIST Atomic Weights and Isotopic Compositions.

The values are facts and free to use; this page’s selection and presentation are © 2026 ScienceQuest.

Measured properties of yttrium

From PubChem, the US National Institutes of Health. Public domain.

Melting point 1795 K (1521.9 °C), 29th of 103 by melting point
Boiling point 3618 K (3344.9 °C), 24th of 93 by boiling point
Density 4.47 g/cm³, 67th of 96 by density
State at room temperature Solid
Electronegativity 1.22 (Pauling), joint 77th of 95 by electronegativity
Van der Waals radius 219 pm, 36th of 99 by atomic radius
First ionisation energy 6.217 eV (599.8 kJ/mol), 67th of 102 by first ionisation energy
Electron affinity 0.307 eV (29.6 kJ/mol), 51st of 57 by electron affinity
Common oxidation states +3
Discovered 1794

Each rank counts down from the highest value, among the elements PubChem’s table gives one for, and links to that property ranked across the whole table. All of them are collected under periodic trends.

Yttrium electron configuration

The full electron configuration of yttrium is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d1 5s2. With the noble-gas core collapsed it is [Kr] 4d1 5s2, and the outermost subshell is 5s2.

Bohr model of yttrium (Y): a nucleus and five shells holding 2, 8, 18, 9 and 2 electrons from the inside out.
Bohr model of yttrium (Y). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.
Orbital box diagram of yttrium (Y), [Kr] 4d1 5s2, with the krypton core drawn as one bar: one box per orbital, filled by Hund’s rule, showing one unpaired electron, in 4d.
Orbital diagram of yttrium (Y). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.

Why group and block follow from this is set out in how the periodic table maps electron configuration, and the electron configuration of every element is listed on one page.

Mass of one yttrium atom

A molar mass is grams per mole, so dividing by the Avogadro constant gives the mass of a single atom, or for an element with more than one natural isotope the average mass of its atoms, and the reciprocal gives how many atoms sit in a gram.

Mass of one atom

  1. one atom = 88.906 / (6.02214076 × 10²³)
  2. = 1.4763 × 10⁻²² g

Atoms in one gram

  1. atoms per gram = 6.02214076 × 10²³ / 88.906
  2. = 6.7736 × 10²¹ atoms

Yttrium on the periodic table

Yttrium is in period 5, group 3, in the d-block.

Group 3 is scandium, yttrium and then either lanthanum and actinium or lutetium and lawrencium, depending on which convention a table follows.

The rest of period 5

Work with yttrium