Chapter 7 Molecular compounds Flashcards
Why do simple covalent structures have low Melting point and boiling point?
The covalent bonds within these molecules are strong (covalent) but the bonds between molecules weak (intermolecular forces) and easy to break
Properties of simple covalent structures
- Usually gases or liquids at room temperature (if solid,
they are soft solids) - Low melting points and boiling points
- Do not conduct electricity
Why are Molecular compounds unable to conduct electricity?
There are no Free electrons due to the strong electrostatic forces between the positive nuclei and the negative electrons keeping them in place.
What is a Monomer?
Small molecules that join together
by covalent bonds
Which has a higher melting/boiling point , Polymer or Monomer? why?
Polymer due to the longer chains which contain more intermolecular forces
Long chains get tangled meaning they will need more energy to be broken
What is a polymer?
A long chain molecule made from many monomers joining together.
What are allotropes?
Different structural forms of the same element are called allotropes
What are molecules?
Molecules are atoms joined by covalent bonds
Can molecules be compounds or elements?
Both! Molecules can be compound ( such as water , H2O ) or element (Such as oxygen, O2)
What are some properties of fullerenes?
Fullerenes have weak intermolecular forces between molecules and so have low melting point these weak forces also make the soft and slippery.
What are the 4 types of carbon allotropes?
Fullerenes , Graphene , Graphite , Diamond
Is Fullerene simple of or complex molecules?
Simple
What Shape is Buckminsterfullerene?
Football
What are some properties of graphene?
Graphene has high melting point due to thew strong covalent bonds and can conduct electricity due to the delocalized electrons that carry electricity.
Is graphene simple or complex and why?
graphene is complex because it consists of a sheet of carbon atoms with no fixed formula
How many carbon atoms is Buckminsterfullerene?
60 carbon atoms
What is a Giant molecular structure?
Giant molecular structures have huge three-dimensional networks of carbon atoms linked by covalent bonds,
Tell me all the properties of Graphite? (5)
Graphite has a high melting point because of many strong covalent bonds that need a lot of energy to be broken. Graphite has three covalent bonds for each carbon atom. This gives graphite a layered structure and means that not all of its electrons are held in covalent bonds. This means it is a good electrical conductor due to the delocalized electrons. weak force’s of attraction allow the sheets of carbon to slide past each other which makes quite soft and useful as a lubricant
Tell me all the properties of Diamond? (5)
diamond has a high melting point because of many strong covalent bonds that need a lot of energy to be broken. Diamonds has four covalent bonds for each carbon atom. The carbon atoms are in a tetrahedral arrangement , joined by strong covalent bonds that gives diamond its extreme hardness and this is why it is used to make cutting tools. Graphite has a high melting point because of many strong covalent bonds that need a lot of energy to be broken.
What are the common properties of metals? (5)
- solids with high melting points
- shiny (when polished)
- malleable
- high density
- good conductors of electricity.
Why are metals malleable?
When you hit a metal, the layers of ions slide over
each other. The ‘sea’ of electrons holds the ions
together and so the metal changes shape instead of
breaking.
What is Metallic bonding?
Metallic bonding is the electrostatic forces of attraction between the positive metal ions and the negative sea of delocalized electron.
Which of the following has a higher electrical conductivity and why? Mg+2 and Na+
Mg+2 because is contributes 2 electrons to the sea of electrons while Na+ only contributes 1
What are the properties of Metallic bonding?
Hight Melting/boiling point
Solid at room temperature
Malleable
Conduct electricity when Solid or liquid
