Unit 7 - Ionic and Metallic Bonding

Ionic bonds

the electrostatic attraction between cations (metals) and anions (non-metals); electrons are transferred from cation to anion

Ex: SrCl₂

Electrolytes

solution with dissociated ionic compounds

Ionic compounds physical properties

• Solid at room temp

• High melting point

• Conduct electric currents when aqeuos or molten

When an ionic compound is put in water…

it dissociates; NaCl(s) → Na⁺(aq) + Cl^-(aq)

Polyatomic ion

made up of many atoms and carries an overall charge

Six polyatomic that must be memorized

OH^1- (hydroxide), NO₃^1- (nitrate), SO₄^2- (sulfate), CO₃^2- (carbonate), PO₄^3- (phosphate), NH₄¹⁺ (ammonium)

Lewis dot diagram

1 dot represents 1 valence electron

Ionic bonding with lewis dot structures

elements with valence electrons then show charge with brackets

Metallic bond

type of chemical bond that occurs between metal atoms

Ex: Fe

Model of valence electrons in metallic bonding name

Sea of electrons

Delocalized electrons

electrons are free flowing – they are no longer restricted to the atom they “belong” to

Physical properties of metals

• Malleable

• Shiny

• Ductile

Alloys

substance that combines more than one metal or mixes a metal with other non-metallic elements

When do you use roman numerals?

Only when dealing with transition metals (except silver which is always +1 and zinc which is always +2) and metals in groups 14 and 15