Chemistry Chapter 4

• Be    [He]2s^2  2 is the valence electron 
• Group number corresponds with valence electron

• Z
• number of protons in an atom

• Zeff 
• magnitude of positive charge the electron can feel 

because distance from nucleus and electron "shielding"

only H Z = zeff

Zeff = Z - σ (shielding constant)

Core b/c closer to nucleus so pulled in more thus shielding the nucleus from the other nucleus

L → R, Zeff ↑

• Metallic Radius - middle of atom to middle of atom
• Covalent Radius - atoms overlap and its middle to middle

• L → R, atomic radius ↓
• b/c more positive (and negative) charges which makes attraction stronger (Zeff ↑)

• Top → Bottom, Atomic Radius ↑
• b/c n↑ and distance from the nucleus ↑

minimum energy (KJ/mol) required to remove 1 mole of e- from 1 mole of an atom in the gas phase 

Cation forms

forms positive charge 

valence electron has been TAKEN

• L → R, Zeff ↑, IE↑
• Top → Bottom, IE ↓ (because further from nucleus)

note, if have higher IE, less likely for an e- to be removed

• paired electrons are harder to remove
• also harder to remove if its a half filled set

• energy released when an atom in the gas phase accepts an electron 
• anion form

forms negative charge

GIVEN a valence electron

L → R, EA ↑

Note: ↑in EA means its more likely for an atom to accept an e- 

if Zeff ↑, then adding more protons and it becomes easier to add e-

• L → R, MC ↓
• Top to bottom, MC ↑

Monoatomic ions - single atoms that's cation or anion

when atoms "become" like noble gases

• Zn2+
• Ag+
• Cu+/Cu2+
• Fe2+/Fe3+

• e- - e- repulsion ↓
• less shielding 
• ionic radius ↓

• e- - e- repulsion ↑
• more shielding 
• ionic radius increases ↑

• L → R, ionic radius ↓
• Top → Bottom, ionic radius ↑