C3 Structure and bonding Flashcards
What is a molecule?
A group of two or more atoms joined together by covalent bonds.
What is a substance?
A substance is matter that contains only one type of atom or molecule.
What is a covalent bond?
The attraction between 2 atoms that share one or more pairs of electrons.
What are the limitations of using the ball and stick method?
You cannot draw rotated bonds, and you cannot express 3D molecules.
Why do simple molecules have low melting and boiling points?
Because the forces of attraction are really low and easy to break. The intermolecular forces between the molecules are weak and can be broken at low temperatures ( less energy to break), meaning the low melting and boiling points.
Why do simple molecules not conduct electricity?
Because all the valence Electrons are bonded together and are unable to move.
What are simple molecular bonds?
Molecules containing a few atoms joined together by covalent bonds.
What are some examples of simple molecular bonds?
Hydrogen, chlorine, water and methane.
What are some properties of simple molecules?
Low ,melting and boiling points, no electrical conductivity, strong covalent bonds between atoms but weak intermolecular forces between molecules.
What is the general formula for alkanes?
CnH2n+2
n= carbon atoms
2= twice the number of carbons +2
What is an alkane?
A saturated hydrocarbon, eg methane, ethane
Word symbol for methane is?
CH4
Word symbol for ethane is?
C2H6
What is a giant covalent structure?
a structure in which very large numbers of atoms are joined together by covalent bonds in a regular network.
What is an intermolecular force?
A force of attraction that exists between molecules.
What are the properties of giant covalent structures?
High melting and boiling points, many very strong covalent bonds between atoms, not soluable in water, they are hard and do not conduct electricity. ( except graphite)
Why can graphite conduct electricity?
Graphite is able to conduct electricity because each carbon atom is has three bonds, leaving one delocalised electron that can move freely and carry charge, meaning it can conduct electricity.
Why is diamond unable to conduct electricity?
Diamond has a very strong covalent structure. It has 4 bonds per atom and no free electrons. This means that there are no electrons to conduct electricity and therefore diamond is unable to conduct electricity.
What is a lattice?
A closely packed, regular arrangement of particles.
What are some examples of giant covalent structures?
Diamond, graphite and silicon dioxide.
What is a polymer?
A long chain molecule that is formed by joining lots of smaller molecules (monomers) together.
Why is diamond hard?
Diamond is hard because it has a giant covalent structure, with strong covalent bonds between each atom.
Why is graphite slippery?
The weak attractive forces between graphites layers means that the layers can easily slide across eachother.
What is an allotrope?
Different structural forms of the same element. They have different physical and structural properties and therefore different uses.
What are some examples of allotropes?
Carbon has allotropes, e.g diamond, graphite and fullerenes.
What is diamond made of and what is its structure?
Diamond is made of carbon atoms bonded by covalent bonds.
It has a giant covalent structure, in a giant crystal lattice.
What is diamond used for?
Tip of a drill, jewellery
What is graphite made of and what is its structure?
Graphite is made of carbon atoms bonded by covalent bonding.
It has a giant covalent structure (layer like lattice)
What is graphite used for?
Pencil leads, nuclear reactor cores.