Trends in the Periodic Table

Periodic Trends Many trends of elements can be explained by electron configuration and position on the periodic table What we are going to be looking at: Atomic Radius Electronegativity Ionization Energy

Atomic Radius The distance from the center of the nucleus to the outer most energy shell Down a Group: As you go down a group the atomic radius increases

Atomic Radius – Across a Period Have the same number of energy levels but as you go across the number of protons increases pulling in the outer electrons As you go across the period, the atomic radius becomes smaller

Electronegativity The ability of an atom to steal an electron from another atom. Electron Thieves

Electronegativity – Down a Group Li has fewer energy levels than sodium making it easier for the protons in the nucleus to grab another atom’s electron As you move down the electronegativity decreases – its harder to steal electrons

Electronegativity – Across a Period Both have the same number of energy levels, but Be has more protons pulling stronger on another atom’s electrons As you move across a period, the electronegativity increases – easier to steal electrons

Ionization Energy The ability of an atom to hold onto it’s outer electrons The bigger the value the harder to lose (the stronger it is holding its electrons)

Ionization Energy – Across a Period Both have the same number of energy levels, but Be has more protons pulling stronger on the outer most electron As you move across a period, the ionization energy increases (harder to lose outer electrons)

Ionization Energy – Down a Group Na has more energy levels (farther from protons) than Li making it easier to lose the outer electrons As you move down a group, the ionization energy decreases (easier to lose outer electrons)