7.3 Flashcards
What kind of structure do metals have?
Giant metallic structure and they have metallic bonding
What is the structure of metals?
Each atom donates an electron to a shared pool of electrons (delocalised electrons throughout the whole structure) Positive ions (cations) left behind Metallic bonding is the strong electrostatic attraction between the positively charged cations and delocalised electrons.
What are the properties of metals?
Strong metallic bonds
High electrical conductivity
High melting and boiling melts
Malleable since uniform layers of positive ions can slide over each other, the delocalised electrons prevent fragmentation
They are nearly always solid at room temp except mercury
Can metals conduct electricity?
Metals conduct electricity in solid and liquid states, and when voltage is applied, the delocalised electrons can move, carrying the charge.
Why is the melting and boiling point of metals high?
High temprature needed in order to provide enough energy to break the bonds (aka the strong electrostatic attraction) between cations and electrons. The strong attraction in most metals having a high MP and BP.
Are metals soluble?
No
What is the structure of non metallic elements?
These exist as simple covalently bonded molecules which form simple molecular lattice (giant covalent lattice)held by weak intermolecular forces- these structures have low melting and boiling points.
Noble gases are monatomic so have very weak induced dipole dipole forces
What do non metals like carbon, boron and silicon structure?
Giant covalent lattice
What is the structure of carbon and silicon?
Found in group 4 of the preodic table therefore contain 4 electrons in its outer shell to form 4 bonding regions- thus it has a tetrahedral structure with a 109.5 degrees bond angle.
What is the solubility of non metallic elements?
Giant covalent structures are always insoluble in all solvents because covalent bonds are too strong to be broken by interactions with the solvent.
Are non metals able to conduct electricty?
Diamond cannot conduct electricty while graphene and graphite can.
Why can’t diamond conduct electricity?
Because all 4 electrons are involved in covalent bonding therefore there are no free electrons to conduct electricty.
Tetrahedral structure
It is one of the hardest materials- macro molecular structure
It will not dissolve in any solvent
How can graphene conduct electricty?
Single layer of graphite composed of hexagonally arranged carbon atoms linked by strong covalent bonds.
Strong
Conducts electricity easily
Insoluble due to strong covalent bonds
How does graphite conduct electricty?
Parallel layers of hexagonally arranged carbon atoms, these layers stacked together by weak London forces between them. One carbon atom is bonded to 3 other carbon atoms in flat sheets leaving one delocalised electron carry the charge. The weak intermolecular forces between the layers make graphite a good lubricant since they can slide over each other
High melting point
The layers are quite far apart making it easy for them to slide over each other and also means it’s less dense than diamond
Insoluble in any solvent
What are the periodic trends in melting points?
Melting point increases from group 1 to group 4.
There is a sharp decrease in melting point between 4 and 5 (bcz these are simple molecular structures)
Melting points are low from 5 to 0
