Recall that in a neutral atom: atomic number = # protons = # electrons

neutral Tc → atomic number = 43 → number of electrons = 43

Use the shortened electron configuration by including a noble gas:

▪ The closest noble gas before Tc: Krypton (Kr)

▪ Electrons after Krypton (Kr): 5s²4d⁵

• Condensed electron configuration of neutral Tc:

Tc: [Kr]5s²4d⁵

• The (+4) charge in Tc⁴⁺ means that 4 electrons were removed from the neutral Tc

• Remove 4 electrons from the highest numbered orbital first (2 from 5s and 2 from 4d)

Electron configuration of Tc⁴⁺:

Tc4+: [Kr]4d³

To determine the number of unpaired electrons, draw the orbitals

3 unpaired electrons

Answer:

electron configuration: [Kr]4d³

unpaired electrons: 3

Determine which orbital will lose electrons if a Ca atom forms a cation of 2+ charge.