Phosphorus (P)
Element 15 · reactive nonmetal · group 15, period 3
Phosphorus is element 15, a reactive nonmetal in group 15 and period 3. Its electron configuration is [Ne] 3s2 3p3. That leaves 5 valence electrons in the outer shell, with the shells filling 2, 8, 5. It is 3 electrons short of a full octet, so it gains them and carries a charge of -3.
- 15 protons
- 5 valence e−
- -3
- p-block
Phosphorus Lewis dot structure
Phosphorus has 5 valence electrons, so its Lewis symbol carries 5 dots: one pair and three single dots. The dots go one to a side before any of them pair up, so the unpaired ones show exactly how many bonds the atom tends to form. The ion has gained 3 more to fill its shell, so all 8 are drawn as pairs.
Draw it in the Lewis structure generator →
Properties
| Atomic number | 15 |
|---|---|
| Symbol | P |
| Standard atomic weight | 30.974 u |
| Group | 15 |
| Period | 3 |
| Block | p-block |
| Category | reactive nonmetal |
| Electron configuration | 1s2 2s2 2p6 3s2 3p3 |
| Noble-gas notation | [Ne] 3s2 3p3 |
| Electrons per shell | 2, 8, 5 |
| Valence electrons | 5 |
| Common ionic charge | -3 |
| Electronegativity (Pauling) | 2.19 |
| Protons / electrons | 15 / 15 |
Electron configuration of phosphorus
Orbitals fill from the lowest energy upward. Writing that out for phosphorus gives 1s2 2s2 2p6 3s2 3p3, which is 1s2 2s2 2p6 3s2 3p3 in plain text.
Everything up to Ne is the same as in that noble gas, so it is usually abbreviated to [Ne] 3s2 3p3. The part outside the bracket is what does the chemistry.
| Subshell | Electrons | Capacity |
|---|---|---|
| 1s | 2 | 2 |
| 2s | 2 | 2 |
| 2p | 6 | 6 |
| 3s | 2 | 2 |
| 3p | 3 | 6 |
Phosphorus ion charge
Phosphorus commonly forms ions with a charge of -3.
It has 5 valence electrons, so it is 3 short of a full octet and 5 above an empty outer shell. An atom takes whichever route is shorter, which is why the charge comes out as it does.
Common questions
What is the Lewis dot structure of phosphorus?
The symbol P with 5 dots, one for each valence electron: one pair and three single dots. Dots go one to a side before any pair up, the same way electrons fill separate orbitals before sharing one. The P3- ion is drawn in brackets with all eight, because it has gained 3.
How many valence electrons does phosphorus have?
Phosphorus has 5 valence electrons. For a main-group element the count is the group number minus 10, and phosphorus is in group 15.
What is the electron configuration of phosphorus?
1s2 2s2 2p6 3s2 3p3, or [Ne] 3s2 3p3 written from the previous noble gas. Orbitals fill lowest energy first.
What is the charge of phosphorus?
Phosphorus commonly forms ions with a charge of -3. With 5 valence electrons it is 3 short of an octet and 5 above an empty shell, so it takes whichever route is shorter.
How many protons, electrons and neutrons does phosphorus have?
A neutral phosphorus atom has 15 protons and 15 electrons. Its standard atomic weight is 30.974, so the most common isotope has about 16 neutrons.
Phosphorus in Lewis structures
What the configuration above means in practice. Phosphorus brings 5 valence electrons to each of these, and the working on every one of them starts by counting exactly that.
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