Rubidium (Rb): Bohr Model, Protons, Neutrons & Electrons
Rubidium is element number 37, an alkali metal in group 1, period 5. Its atom has 37 protons, 48 neutrons and 37 electrons arranged in 5 shells: 2, 8, 18, 8, 1.
Protons, neutrons and electrons in rubidium
ال atomic number of rubidium is 37, so every rubidium atom has 37 protons. A neutral atom has the same number of electrons, 37. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For rubidium-85, that is 85 − 37 = 48 neutrons. Rubidium has 2 stable isotopes, with 48, 50 neutrons.
How to draw the Bohr model of rubidium
- Draw the nucleus and write 37 p⁺ تم تصميم [الخدمة] لمتعلمين من جميع الأعمار، بما في ذلك طلاب المدارس. 48 n⁰ inside it.
- Draw the first shell and put 2 electrons on it (the first shell holds at most 2).
- Draw the second shell and put 8 electrons on it.
- Draw the third shell and put 18 electrons on it.
- Draw the fourth shell and put 8 electrons on it.
- Draw the fifth shell and put 1 electron on it.
- Check: 2 + 8 + 18 + 8 + 1 = 37 electrons, the same as the number of protons.
From potassium onwards the shells don’t simply fill as 2, 8, 8: the fourth shell starts before the third is full, so the real arrangement above (2, 8, 18, 8, 1) is the one to draw.
Electron configuration
The electron configuration of rubidium is [Kr] 5s¹. Its 1 outer electron decides how it reacts: it tends to lose it, forming Rb⁺ ions.
Key facts about rubidium
| Symbol | Rb |
|---|---|
| Atomic number | 37 |
| Relative atomic mass | 85.468 |
| Group · period · block | group 1 · period 5 · s-block |
| نوع | فلز قلوي |
| State at 25 °C | solid |
| أغلفة الإلكترون | 2, 8, 18, 8, 1 |
| Electron configuration | [Kr] 5s¹ |
| Valence electrons | 1 |
| Common ion | Rb⁺ |
| Electronegativity (Pauling) | 0.82 |
| First ionisation energy | 4.18 eV (403 kJ/mol) |
| Atomic radius (empirical) | 235 pm |
Where rubidium sits on the periodic table
الأسئلة الشائعة
How many protons, neutrons and electrons does rubidium have?
Rubidium has 37 protons and 37 electrons (atomic number 37). Its most common isotope, rubidium-85, has 85 − 37 = 48 neutrons.
What is the electron configuration of rubidium?
[Kr] 5s¹. In shells that is 2, 8, 18, 8, 1.
How many valence electrons does rubidium have?
1. Rubidium is in group 1, and its outer shell holds 1 electron.
Where is rubidium on the periodic table?
In group 1, period 5, in the s-block. It is an alkali metal.
