Periodic table trends Answers

Ionization energy vs. atomic number

Trends in Ionization Energy Noble gases exhibit the highest ionization energy Alkali metals exhibit the lowest ionization energy

Atomic radius vs. atomic number

Trends in Atomic Radius Alkali metals have the largest atomic radii Noble gases have the smallest atomic radius Atomic radius is inversely related to ionization energy. As atomic radius increases, ionization energy decreases.

Atomic Radius One half the distance between nuclei of identical atoms that are bonded together (the radius of an atom) Decreases across a period increasing positive nuclear charge more protons but same number of electron shells Increase down a group increasing number of electron shells outer electrons are farther from the nucleus

Ionization Energy The energy required to remove an electron from a neutral atom IE increases across a period Atoms are getting smaller, electrons are closer to the nucleus, stronger attractive force IE decreases down a group Atoms are getting larger, electrons are farther from the nucleus Outer electrons becomes increasingly more shielded from the nucleus by inner electrons Metals have characteristically low IE Nonmentals have high IE Noble gases have a very high IE Stable octet, full valence shell

Ionic Radius Radius of an ion (an atom that has gained or lost electrons) Cations have a smaller ionic radius than corresponding atom Protons outnumber electrons Less shielding of electrons Therefore, stronger attractive forces Anions have a larger ionic radius than corresponding atom Electrons outnumber protons Greater electron-electron repulsion Therefore, weaker attractive forces

Electron Affinity An atom’s ability to attract an electron Increases across a period Atomic radius decreases, stronger attractive forces Decreases down a group Atomic radius and shielding by inner electrons increases, weaker attractive force

Electronegativity An atom’s ability to attract electrons when bonded We will explore this more later

Electronegativity Electronegativity