Types of substance Flashcards
How are ionic compounds held together
The oppositely charged ions are strongly attracted to on another by electrostatic forces
What are the properties of ionic compounds
- High melting and boiling points
- Solid compounds don’t conduct electricity, only when molten or dissolved
- Many are soluble in water
Why do ionic compounds have high melting and boiling points
The strong attraction between ions requires a large amount of energy to overcome
Why can’t ionic compounds conduct electricity when solid
Although the particles are charged, they are fixed in place and can’t move
How are covalent bonds formed
When a pair of electrons is shared between two atoms
State some allotropes of carbon
- Diamond
- Graphite
- Graphene
What is structure of diamond
Diamond is made up of a network of carbon atoms that each form four covalent bonds
What are the properties of diamond
- High melting point
- Strong covalent bonds hold the atoms in a rigid lattice structure making diamond hard
- Cannot conduct electricity because it has no free electrons or ions
What is the structure of graphite
Each carbon atom only forms three covalent bonds, creating sheets of carbon atoms arranged in hexagons
What are the properties of graphite
- The layers are only held together weakly, so they’re free to move over each other
- High melting point
- Conducts electricity since each carbon atom has one delocalised electron
What is the difference between simple molecular substances and giant covalent structures
In giant covalent structures all atoms are bonded to each other
What is the structure of graphene
A single sheet of graphite that is one atom thick, making it a two-dimensional compound
What is the structure of fullerenes
- Shaped like closed tubes or hollow balls
- Mainly arranged in hexagons
How are particles arranged in metals
The electrons in the outer shell are delocalised. There are strong forces of electrostatic attraction between the metal ions and the shared electrons
Why are metals malleable
The layers of atoms in a pure metal can slide over each other
