C2 Chem Flashcards
Giant covalent structure
All atoms are covalently bonded in a massive network such as diamond
Are sometimes called macro molecular substances
Giant covalent structure has a high or low melting point?
High
Diamond properties
- Carbon atom is joined to four other covalent bonds
- Has high melting point because a lot of covalent bonds has to be broken
- is very hard because atoms are bonded in a rigid network
- it is an insulator because there are no free electrons to move around
Properties of graphite
- carbon atom is joined to three covalent bonds that forms layers
- very high melting point because a lot of covalent bonds have to be broke
- soft and slippery because the layers can slide over each other
- conductor because it has delocalized electrons
What are fullerenes?
How many carbon does it contain?
Are molecules made up of linked carbon rings
It contains 60 carbon atoms in a spherical shape
Simple molecular substance
- There are millions of separate but identical molecules such as water
Low melting and boiling points because it has weak intermolecular forces - Non conductive because the electrons are not free to move
What is an alloy?
A mixture of a metal with small amounts of other metals or carbon
Why can metals be bent and hammered into shape?
Because the layers of metal atoms can slide over each other easily whilst maintaining the metallic bonding
Why are alloys harder than pure metal?
Because different metal atoms in alloys jam up the metal structure that stops the layers of atoms from sliding past each other easily
What is a shape memory alloy?
Example?
An alloy that can return to its original shape after being deformed
Nitinol
What are the uses of a shape memory alloy such as nitinol?
Wires in dental braces
Structure of thermo softening polymers
- Long polymer chains are not joined up
- they soften and melt when heated because they have weak intermolecular forces
Stricture of thermosetting polymers
- polymer chains are joined to each other by strong covalent bonds that makes them not soften or melt
What are atoms?
A particle with no overall charge
What is an element?
Element is a substance made up of only 1 atom
What is a compound?
A substance made up of more than type of atom that are chemically joined together
How are compounds broken down?
By thermal decomposition or electrolysis
Rules for covalent bonding
- A pair of electrons are shared between 2 atoms
- between nonmetals only
Rules for ionic bonding
- electrons are transferred between 2 atoms
- occurs between metal and non metal
What is nanoScience?
The study of nanoparticles
Why are nanoparticles have different properties?
They have a much larger surface area to volume ratio
What are the uses of nanoparticles?
They can be used as sensors for example, to detect toxic lead ions
They can be used in clothes to kill bacteria and prevent smells
What are the concerns of nanoparticles?
- since they have different properties, they may be toxic
- they might be more reactive than bulk material
Definition of a nanoparticle?
A particle between 1 - 100 nanometer in size
