Periodic Table: Trends

Atomic Radius

Down a group:AR ↑ because # of energy levels ↑

Across a period: Right to leftAR ↑ because of ↓ in p+ attraction to surrounding e-

Increasing

Increasing

1716 18

Increasing atomic radius

16 p+ in nucleus16 e- in 3 energy levels

Same Period on Periodic Table17 p+ in nucleus

17 e- in 3 energy levels18 p+ in nucleus

18 e- in 3 energy levels

SOME attraction between p+ in nucleus and e-

Large atom

MORE attraction between p+ in nucleus and e-

Smaller atom

MOST attraction between p+ in nucleus and e-

Smallest atom

Trend in Atomic Radius

BIGGEST

Atomic Radius Examples

Which element is larger? Explain. Silicon or Sulfur

Which element is smaller? Explain. Barium or Zirconium

Zr has 5 energy levels, Ba has 6, so Zr is smaller

Silicon’s p+ don’t attract the e- as close as Sulfur’s p+ do

NaMetalValence e-: 1

ClNonmetal

Valence e-: 7

Ionic radius vs Atomic Radius

Now Na has a +1 charge…smaller radius

And Cl has a -1 charge…larger radius

Cation < Atom < AnionFor radius:

Ionization Energy (IE) The energy required to remove one valence

electron from an atom to make a cation.

F

Kr

Be

C

Ionization Energy (IE)

Up a group: IE ↑ because # of

energy levels ↓ (more p+ and e- attraction)

Across a period: IE ↑ because of # of

valence e- increases

Ionization Energy

Increasing

Trend in Ionization EnergyHIGHEST

Ionization Energy: Examples

Which element has a higher ionization energy? Explain. Silicon or Sulfur

Which element has a lower ionization energy? Explain. Barium or Zirconium

S requires more E to remove an e-

because has 6 val e-, close to desired 8

Ba has more energy levels, so easier to take an e- away than Zr

The ability for an atom to attract electrons in a chemical bond (atoms strength)

Related to # of valence electrons

Related to p+ and e-

attraction

Electronegativity (EN)

F

H

Electronegativity (EN)

Increasing

Increasing

Up a group:EN ↑ because #

of energy levels ↓ (more p+ and e-

attraction)

Across a period: EN ↑ because

of # of valence e- increases

Trend in Electronegativity

HIGHEST

DO NOT include Noble Gases (don’t bond)

Electronegativity Examples

Which element is more electronegative? Explain. Silicon or Sulfur

Which element is less electronegative? Explain. Barium or Zirconium

S wants more e- because has 6 val e- only needs 2 more

Ba has 1 more energy level, so less attraction with highest energy e-