Ruthenium (Ru)
Ruthenium is element 44, a transition metal in group 8, period 5. A neutral atom has 44 protons, 57 neutrons and 44 electrons, 1 of them valence electrons.
Transition metal- Atomic number
- 44
- Atomic mass
- 101.1 u
- Valence electrons
- 1*
- Protons · neutrons
- 44 · 57
- Electrons per shell
- 2, 8, 18, 15, 1
- At room temperature
- solid
Bohr model of ruthenium
The Bohr model draws ruthenium as a nucleus of 44 protons and 57 neutrons, with its 44 electrons on 5 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 15 in shell 4, 1 in shell 5. Press Build the atom to watch the shells fill from the inside out. The outer ring (the O shell) is dashed: the electrons there are the ones that take part in chemistry.
Real electrons don't travel in neat circles. They live in fuzzy orbitals, shown below, but the Bohr picture is the quickest way to count shells and valence electrons.
Electron configuration of ruthenium
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹ 4d⁷
Short form (noble gas notation): [Kr] 5s¹ 4d⁷. The [Kr] stands for the electrons of krypton, the noble gas before it.
Ruthenium breaks the usual filling order. The Aufbau rule predicts 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d⁶, but experiments show the configuration above. The energy levels of the subshells are so close here that a different arrangement wins.
How many valence electrons does ruthenium have?
Ruthenium has 1 valence electron.
Ruthenium is a transition metal, so its valence electrons are less clear-cut than for main-group elements. It has 1 electron in its outermost shell (shell 5), and electrons in its inner d subshell can also take part in bonding.
Protons, neutrons and electrons
| Protons | 44 | equal to the atomic number |
|---|---|---|
| Electrons | 44 | equal to the protons in a neutral atom |
| Neutrons | 57 | mass number 101 − 44 protons |
Atoms of the same element can have different numbers of neutrons (isotopes). The count above uses the rounded atomic mass, the way it's taught in class.
Ruthenium properties
| Symbol | Ru |
|---|---|
| Category | Transition metal |
| Group · period · block | 8 · 5 · d |
| Atomic mass | 101.1 u |
| State at 25 °C | solid |
| Melting point | 2,607 K (2,330 °C, 4,230 °F) |
| Boiling point | 4,423 K (4,150 °C, 7,500 °F) |
| Density | 12.1 g/cm³ |
| Electronegativity (Pauling) | 2.2 |
| Atomic radius | 207 pm |
| First ionization energy | 7.361 eV |
| Electron affinity | 1.05 eV |
| Oxidation states | +3 |
| Common ion charge | +3 |
| Discovered | 1827 by Karl Ernst Claus |
Where ruthenium sits on the periodic table
Group 8: Iron, Osmium, Hassium.
Questions about ruthenium
How many valence electrons does ruthenium have?
Ruthenium has 1 valence electron in its outer shell; inner d or f electrons can also bond.
How many protons, neutrons and electrons does ruthenium have?
A neutral ruthenium atom has 44 protons and 44 electrons. Its most common form has about 57 neutrons (mass number 101 − 44 protons).
What is the electron configuration of ruthenium?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹ 4d⁷, written in short form as [Kr] 5s¹ 4d⁷.
What does the Bohr model of ruthenium look like?
A nucleus of 44 protons and 57 neutrons, circled by 5 electron shells holding 2, 8, 18, 15, 1 electrons.
What is the atomic number of ruthenium?
44. The atomic number is the number of protons in the nucleus, and it is what makes an atom ruthenium.