Yttrium at a glance
- Atomic number
- 39
- Symbol
- Y
- Atomic mass
- 88.906 u
- Category
- Transition metal
- Group / period
- 3 / 5
- Electron configuration
- [Kr] 4d 1 5s 2
- State at 25 °C
- Solid
- Melting point
- 1526 °C
- Boiling point
- 3336 °C
- Density
- 4.469 g/cm³
- Electronegativity
- 1.22
- 1st ionization energy
- 600 kJ/mol
- Oxidation states
- +3
- Discovered
- 1794
Atomic structure
A neutral yttrium atom has 39 protons and 39 electrons, and its most common isotope carries about 50 neutrons. One atom weighs about 1.48 × 10⁻²⁵ kg, so a mole of yttrium (6.022 × 10²³ atoms) weighs 88.906 g. That nucleus holds 1.28 neutrons for every proton. The electrons fill 5 shells (K 2, L 8, M 18, N 9, O 2), which gives the configuration [Kr] 4d 1 5s 2. As a d-block element, both its outer s electrons and its inner d electrons can take part in bonding, which is why it shows more than one oxidation state. It has only one stable isotope, Y-89. No other element has a stable isotope with mass number 89, so Y-89 has no stable isobars; its neighbours on that line decay into it or away from it.
Physical properties
At room temperature (25 °C) yttrium is a solid. It melts at 1526 °C and boils at 3336 °C, so it stays liquid across a 1810-degree range. It stays solid in a candle flame (about 1000 °C) but would melt in molten iron (1538 °C). Its density is 4.469 g/cm³, 4.47 times as dense as water. Its atoms have a radius of about 180 pm (Strontium next door is 200 pm). In the solid, its atoms pack into a hexagonal close-packed lattice.
Chemical behaviour
Its electronegativity is 1.22 on the Pauling scale. Pulling off its outermost electron takes 600 kJ/mol, less than Scandium above it (633 kJ/mol). A bond between yttrium and chlorine would be mostly ionic, with an electronegativity difference of 1.9. It releases 30 kJ/mol when it gains an extra electron. Its common oxidation states are +3, so in compounds you will usually meet it as Y³⁺. Group 3 also holds Scandium, which shares its outer-shell pattern.
Where it comes from
It makes up 33 mg/kg of Earth's crust, the 29th most abundant element there. It was first identified in 1794, making it the 31st element to be discovered (counting the 11 known since antiquity together).