Ch7- Periodicity

* Bonding - Ionic Bonding (electrostatic attraction) * Way that atoms combine - atoms lose and gain e- * Forces holding particles together - strong ionic bonds between + and - ions * MP/BP - High ; strong ionic bonds between cations and anions which require large amount of energy to overcome * Electrical Conductivity - Doesn’t conduct electricity as solid, DOES conduct when molten/(aq) as ions are free to move

• Bonding: Covalent • Way that atoms combine: atoms share e- • Forces holding the particles together: strong covalent bonds between atoms • MP/BP- high ; strong covalent bonds between atoms which require a lot of energy to overcome • Electrical Conductivity: does NOT conduct electricity. No ions/electrons which can move. EXCEPT Graphite.

• Bonding: covalent • Way that atoms combine: atoms share electrons • Forces holding the particles together: weak intermolecular forces between molecules • MP/BP: Low ; weak intermolecular forces between molecules easy to break • Electrical Conductivity: Does NOT conduct electricity. no free to move ions/electrons.

• Bonding: Metallic • Way that atoms combine: atoms lose e- • Forces holding the particles together: strong metallic bonds between ions and delocalised e- • MP/BP: High ; strong metallic bonds between ions + delocalised e- require large amount of energy to overcome • Electrical Conductivity: conducts electricity when solid as it contains delocalised e- which are free to move.

• Charge on ions: the greater the charge, the greater the electrostatic attraction • Size of ions: generally, smaller the ion, the greater the electrostatic attraction. 1. As radius of cations increases down Gr1/2, MP decreases 2. Smaller ions can pack closer therefore have greater charge density, greater electrostatic attraction, ionic bond stronger, MP increases.

I.E. measures how easily an atom loses e- to form positive ions.

As you go down Gr7, BP increases, as the molecules are bigger, and there are more electrons, more Ar, stronger London Forces. Electronegativity decreases as Atomic Radius increases and more shielding so less attraction.

As you go down Gr7, the halogens get less reactive (larger atomic radius, therefore less nuclear attraction, so less likely to be readily accepting an electron)