بيريليوم (Be): Bohr Model, Protons, Neutrons & Electrons
بيريليوم is element number 4, an alkaline earth metal in group 2, period 2. Its atom has 4 protons, 5 neutrons and 4 electrons arranged in 2 shells: 2, 2.
Protons, neutrons and electrons in beryllium
ال atomic number of beryllium is 4, so every beryllium atom has 4 protons. A neutral atom has the same number of electrons, 4. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For beryllium-9, that is 9 − 4 = 5 neutrons.
How to draw the Bohr model of beryllium
- Draw the nucleus and write 4 p⁺ تم تصميم [الخدمة] لمتعلمين من جميع الأعمار، بما في ذلك طلاب المدارس. 5 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 2 electrons on it.
- Check: 2 + 2 = 4 electrons, the same as the number of protons.
Electron configuration
The electron configuration of beryllium is [He] 2s². Its 2 outer electrons decide how it reacts: it tends to lose them, forming Be²⁺ ions.
Key facts about beryllium
| Symbol | Be |
|---|---|
| Atomic number | 4 |
| Relative atomic mass | 9.0122 |
| Group · period · block | group 2 · period 2 · s-block |
| نوع | فلز أرضي قلوي |
| State at 25 °C | solid |
| أغلفة الإلكترون | 2, 2 |
| Electron configuration | [He] 2s² |
| Valence electrons | 2 |
| Common ion | Be²⁺ |
| Electronegativity (Pauling) | 1.57 |
| First ionisation energy | 9.32 eV (899 kJ/mol) |
| Atomic radius (empirical) | 105 pm |
Where beryllium sits on the periodic table
الأسئلة الشائعة
How many protons, neutrons and electrons does beryllium have?
Beryllium has 4 protons and 4 electrons (atomic number 4). Its most common isotope, beryllium-9, has 9 − 4 = 5 neutrons.
What is the electron configuration of beryllium?
[He] 2s². In shells that is 2, 2.
How many valence electrons does beryllium have?
2. Beryllium is in group 2, and its outer shell holds 2 electrons.
Where is beryllium on the periodic table?
In group 2, period 2, in the s-block. It is an alkaline earth metal.
