Chapter 5 Key Concepts

Question 1

Why do electrons have opposite spin?

Answer 1

Opposite spin helps counteract the repulsion between the negative charges of the two electrons.

Question 2

Structure of ionic compounds

Answer 2

Each ion attracts oppositely charged ions in all directions making a giant ionic lattice

Question 3

Melting point and boiling point of ionic lattice

Answer 3

Solids at room temperature because not enuff energy to overcome bonds. High temp needed to overcome high electrostatic force of attraction.

Greater charge means stronger electrostatic attraction between ions
ionic radius affects melting point too.

Question 4

What needs to happen for an ionic lattice to dissolve in a polar solvent?

Answer 4

• ionic lattice breaks down

- water molecules attract and surround the ions

Question 5

Explain the conductivity of ionic lattices

Answer 5

Solid
-ions fixed
-no mobile charge carriers
Aq/liquid
-solid ionic lattice breaks down
-now ions are free to move as mobile charge carriers

Question 6

Why does a lone pair repel more than a bonded pair

Answer 6

-slightly closer to the nucleus
-occupies more space
Decreasing bond angle by 2.5 per LP

Question 7

Polar bonds but not a polar molecule?!

Answer 7

-dipoles are acting in opposite directions and exactly oppose each other cancelling each other out so overall dipole is zero

Question 8

Explain London forces

Answer 8

Exist between all molecules. Polar or otherwise

• movement of electrons makes a changing dispole in a molecule
• at any instant instantaneous dipole exists but it’s position is constantly shifting
• that induces dipole in neighbouring molecule
• induced dipole induces further dipoles which then attract one and other
• only temporary
• more electrons= larger instant and induced dipoles = greater induced di di interaction=stronger LF=increased bp