Oxygen vs Nitrogen
Both are diatomic non-metals, so they share the same broad chemistry.
The differences in plain English
- They share period 2, the same row, so their outer electrons are in the same shell but they differ in how many there are: Oxygen has 6, Nitrogen has 5.
- Both are gass at room temperature.
- Oxygen is denser, only slightly more than Nitrogen (1.429 against 1.251 g/L).
- Nitrogen melts at -210 °C, Oxygen at -219 °C.
- An atom of Oxygen is only slightly heavier than an atom of Nitrogen (16.00 u against 14.01 u).
- Oxygen pulls electrons more strongly in a bond (electronegativity 3.44 against 3.04).
Side by side
| Oxygen | Nitrogen | |
|---|---|---|
| Atomic number | 8 | 7 |
| Symbol | O | N |
| Family | Diatomic non-metal | Diatomic non-metal |
| Group / period | 16 / 2 | 15 / 2 |
| State at room temperature | Gas | Gas |
| Atomic mass | 15.999 u | 14.007 u |
| Density | 1.429 g/L | 1.251 g/L |
| Melting point | -219 °C | -210 °C |
| Boiling point | -183 °C | -196 °C |
| Electronegativity | 3.44 | 3.04 |
| First ionisation energy | 1313.9 kJ/mol | 1402.3 kJ/mol |
| Electron configuration | [He] 2s2 2p4 | [He] 2s2 2p3 |
| Discovered by | Carl Wilhelm Scheele | Daniel Rutherford |
Oxygen
Oxygen is the element that sets fire to wood, turns iron to rust and keeps us alive. It is a colourless gas that forms about a fifth of the air, and it is chemically greedy, grabbing electrons from almost any other element it meets. That greed is the basis of burning, of rusting and of respiration, which is a slow, controlled burning of food inside our cells.
- Oxygen is the most abundant element in the Earth's crust, making up about 46 per cent of it by mass.
- About 65 per cent of the mass of the human body is oxygen, mostly as water.
Nitrogen
Take a breath. About 78 per cent of what just entered your lungs was nitrogen, and almost all of it will leave again unchanged. Nitrogen gas is made of pairs of atoms held together by a triple bond, one of the strongest in chemistry. That bond makes nitrogen so stable that most things ignore it, which is exactly why it fills the air rather than reacting away.
- About 78 per cent of the air by volume is nitrogen.
- The triple bond in a nitrogen molecule is one of the strongest chemical bonds known, which is why nitrogen gas is so unreactive.
Colour the bubbles by density or melting point and the difference jumps out.
More comparisons
Data from Periodic-Table-JSON (CC BY-SA); temperatures rounded to the nearest degree. Written by Anthony.