Alkali metals TRENDS

Atomic Mass- mass of an atom Li 6.941amu Na 22.99amu K 39.098amu Rb 85.468amu Cs 132.905amu Fr 223amu

Atomic size- radius of an atom Li 167pm Na 190pm K 243pm Rb 265pm Cs 298pm Fr n/a

reactivity- ability of an element to undergo chemical changes Reacts with water Na Reacts vigorously with water K Reacts violently with water Rb Explodes upon contact with water Cs Fr --

Shielding effect- full core shells blocking the positive nuclear force from reaching the valence shell Li 2 Na 10 K 18 Rb 36 Cs 54 Fr 86

Ionization energy- energy required to remove an electron Li 520 Na 496 K 419 Rb 403 Cs 376 Fr 380

Electronegativity- tendency of an atom to attract electrons Li 1 Na 0.9 K 0.8 Rb Cs 0.7 Fr