The charge of an alpha particle is +2e = +3.2 × 10⁻¹⁹ coulombs (C). An alpha particle is identical to a helium-4 nucleus, consisting of 2 protons and 2 neutrons. Since each proton carries a charge of +1.6 × 10⁻¹⁹ C, the total charge of 2 protons gives the alpha particle a charge of +3.2 × 10⁻¹⁹ C.
Charge of alpha particle = +2e = +3.2 × 10⁻¹⁹ C.
An alpha particle consists of 2 protons + 2 neutrons (helium-4 nucleus).
Each proton has charge +e = +1.6 × 10⁻¹⁹ C; two protons give +2e.
Mass of alpha particle = 4 amu = 6.644 × 10⁻²⁷ kg.
Alpha particles have high ionising power but low penetrating power.
Alpha emission reduces the atomic number by 2 and mass number by 4.
Alpha particles are stopped by a sheet of paper or a few centimetres of air.
Composition of an alpha particle:
Properties:
| Property | Value |
|---|---|
| Charge | +2e = +3.2 × 10⁻¹⁹ C |
| Mass | 4 amu = 6.644 × 10⁻²⁷ kg |
| Mass number (A) | 4 |
| Atomic number (Z) | 2 |
| Speed in air | ~5–7% of speed of light |
| Penetrating power | Low (stopped by paper or skin) |
| Ionising power | Very high |
In alpha decay, a nucleus emits an alpha particle:
General equation: ²ᴬₓX → ²ᴬ⁻⁴ₓ₋₂Y + ⁴₂He (alpha particle)
Charge is conserved: Z (parent) = (Z−2) (daughter) + 2 (alpha)
Example — Radium-226 decay: ²²⁶₈₈Ra → ²²²₈₆Rn + ⁴₂He
Charge check: 88 = 86 + 2 ✓ Mass check: 226 = 222 + 4 ✓
The alpha particle (+2 charge) carries away 2 protons from the nucleus, reducing the atomic number by 2.
The charge of an alpha particle is +2e = +3.2 × 10⁻¹⁹ coulombs. It consists of 2 protons (each with charge +1.6 × 10⁻¹⁹ C) and 2 neutrons (no charge), giving a total positive charge of 2 × 1.6 × 10⁻¹⁹ = 3.2 × 10⁻¹⁹ C.
An alpha particle is a helium-4 nucleus, consisting of 2 protons and 2 neutrons. It has no electrons, giving it a net charge of +2 elementary charges (+3.2 × 10⁻¹⁹ C).
In alpha decay, the parent nucleus emits an alpha particle with charge +2e. The daughter nucleus has an atomic number 2 less than the parent. Charge is conserved: Z_parent = Z_daughter + 2.
A proton has charge +e = +1.6 × 10⁻¹⁹ C. An alpha particle has charge +2e = +3.2 × 10⁻¹⁹ C, which is exactly twice the charge of a proton. This is because an alpha particle contains two protons.
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