CHEM 1220: Radioactivity

alpha

• Mass # (A) down 4

• Atomic # (Z) down 2

Emits He⁴₂

Beta

• Mass # (A) remains constant

• Atomic # (Z) increases by 1 (neutron → proton)

• Also creates an accompanying electron

• (are positively charged)

Gamma

Is a high-energy photon & is nuclear (has no charge)

• nuclear reactions

Positron emission

Is the antiparticle of the electron (a positive (+) electron; NOT a proton)

• Mass # (A) remains constant

• Atomic # (Z) decreases by 1

A proton creates a positron and a neutron

Electron Capture

Creates a neutron from a proton (+) and an electron (–)

• Mass # (A) remains constant

• Atomic # (Z) decreases by 1

The nucleus ‘eats' an electron and combines it with a proton in the nucleus

If Z > 83

alpha

When too many neutrons & too few protons

beta

If it has too few neutrons & too many protons

positron

If it has too many protons

electron capture

If accompanying alpha or beta decay

gamma

C¹⁴₆ = E^A_Z

Z = 14 is the atomic number (sum of protons and neutrons)

A = 6 is the # of protons

• This example has 6 protons and 8 neutrons