Why is potassium metal soft compared with many other metals?

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A periodic table element box for potassium shows atomic number 19, symbol K, atomic weight 39.0983, electron configuration [Ar]4s1, and name potassium. Icons indicate it is an alkali metal, solid at room temperature, body-centered cubic crystal structure, and has strongly basic higher-valence oxides. A key explains the symbols for alkali metals, solid state, body-centered cubic structure, and strong basicity. — potassium Properties of potassium.

Potassium metal is soft compared with many other metals because of its specific atomic and crystallographic structure. As an alkali metal, potassium possesses a relatively large atomic radius and a body-centred cubic crystal arrangement that is characterized by large interatomic distances and weak bond energies.1

These loose atomic arrays result in low cohesive forces between the atoms, which directly contribute to the metal's softness, low density, and low melting point. Unlike many other metals that feature more tightly packed structures, the weak metallic bonding in potassium allows the atoms to be displaced more easily, making the material soft enough to be cut with a knife.12