Nobelium (No)
Nobelium is element 102, an actinide in the actinide series (period 7). A neutral atom has 102 protons, 157 neutrons and 102 electrons, 2 of them valence electrons.
Actinide- Atomic number
- 102
- Atomic mass
- [259] u
- Valence electrons
- 2*
- Protons · neutrons
- 102 · 157
- Electrons per shell
- 2, 8, 18, 32, 32, 8, 2
- At room temperature
- solid
Bohr model of nobelium
The Bohr model draws nobelium as a nucleus of 102 protons and 157 neutrons, with its 102 electrons on 7 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 32 in shell 4, 32 in shell 5, 8 in shell 6, 2 in shell 7. Press Build the atom to watch the shells fill from the inside out. The outer ring (the Q 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 nobelium
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴
Short form (noble gas notation): [Rn] 7s² 5f¹⁴. The [Rn] stands for the electrons of radon, the noble gas before it.
How many valence electrons does nobelium have?
Nobelium has 2 valence electrons.
Nobelium is a actinide, so its valence electrons are less clear-cut than for main-group elements. It has 2 electrons in its outermost shell (shell 7), and electrons in its inner f and d subshell can also take part in bonding.
Protons, neutrons and electrons
| Protons | 102 | equal to the atomic number |
|---|---|---|
| Electrons | 102 | equal to the protons in a neutral atom |
| Neutrons | 157 | mass number 259 − 102 protons (for its longest-lived isotope, No-259) |
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.
Nobelium properties
| Symbol | No |
|---|---|
| Category | Actinide |
| Group · period · block | — · 7 · f |
| Atomic mass | [259] u |
| State at 25 °C | solid |
| Melting point | 1,100 K (827 °C, 1,520 °F) |
| Boiling point | — |
| Density | — |
| Electronegativity (Pauling) | 1.3 |
| Atomic radius | — |
| First ionization energy | 6.65 eV |
| Electron affinity | — |
| Oxidation states | +3, +2 |
| Common ion charge | +3, +2 |
| Discovered | 1957 by Joint Institute for Nuclear Research |
Where nobelium sits on the periodic table
Actinides: Actinium, Thorium, Protactinium, Uranium, Neptunium, Plutonium, Americium, Curium.
Questions about nobelium
How many valence electrons does nobelium have?
Nobelium has 2 valence electrons in its outer shell; inner d or f electrons can also bond.
How many protons, neutrons and electrons does nobelium have?
A neutral nobelium atom has 102 protons and 102 electrons. Its most common form has about 157 neutrons (mass number 259 − 102 protons).
What is the electron configuration of nobelium?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴, written in short form as [Rn] 7s² 5f¹⁴.
What does the Bohr model of nobelium look like?
A nucleus of 102 protons and 157 neutrons, circled by 7 electron shells holding 2, 8, 18, 32, 32, 8, 2 electrons.
What is the atomic number of nobelium?
102. The atomic number is the number of protons in the nucleus, and it is what makes an atom nobelium.