Solid Structures Flashcards
What are ionic solids made of?
Oppositely charged ions packed around each other.
What is the coordination number of caesium chloride?
8:8 (each ion is surrounded by 8 oppositely charged ions).
Why do ionic solids have high melting and boiling points?
Strong electrostatic attraction between oppositely charged ions requires a lot of energy to overcome.
Why are ionic solids brittle?
When layers shift, like charges align and repel each other, causing the crystal to break.
When do ionic solids conduct electricity?
When molten or dissolved in water, as the ions are free to move and carry charge.
Why are ionic solids electrical insulators as solids?
Ions are fixed in place and cannot move to carry charge.
Which ionic compounds are always soluble in water?
Group 1 compounds, nitrate compounds, and most halide compounds.
How do ionic solids dissolve in water?
Water molecules (which have a permanent dipole) surround and attract the ions.
How is each carbon atom bonded in diamond?
Each carbon bonds to four others in a tetrahedral arrangement.
Why does diamond have a high melting and boiling point?
Strong covalent bonds throughout the structure require a lot of energy to break.
Why is diamond extremely hard?
Each carbon atom is covalently bonded to four others in a strong 3D network, making the structure rigid.
Is diamond a conductor of electricity? Why or why not?
No, diamond is an electrical insulator because all electrons are involved in covalent bonding, so no free electrons are available to carry charge.
Why is diamond insoluble in water and other solvents?
The strong covalent bonds in the structure cannot be broken by interactions with solvent molecules.
Why is diamond used in cutting tools?
Its hardness allows it to cut through other materials without breaking.
What is the structure of graphite?
Hexagonal layers of carbon atoms held together by weak van der Waals forces. Each carbon makes 3 bonds with other carbon atoms.
Why is graphite a conductor?
Each carbon has one free (delocalised) electron per atom that can carry charge.
Why is graphite soft?
Layers can slide over each other due to weak van der Waals forces between them.
Why is graphite insoluble?
Covalent bonds in the structure are too strong to be broken by water molecules.
