Topic 2 - Bonding, Structure and Properties of Matter Flashcards
How do you predict a substance’s state?
Below MP = Solid
Above BP = Gas
In the middle = Liquid
What are ions?
Ions are charged atoms which have either lost or gained an electron
Why do atoms gain or lose an electron?
They do this because they are trying to gain a full outer shell like a noble gas
Why do ionic bonds form?
Because oppositely charged ions are strongly attracted to one another by electrostatic forces to form an ionic bond
Do ionic compounds have a low or high MP and BP and why?
They have a high MP and BP because a greater amount of energy is needed to overcome the strong attraction between a particles
Why can ionic compounds conduct electricity when molten but not when solid?
This is because when they are solid they are in a fixed position and cannot carry a charge contrasted with being molten and able to move
Which groups form ions most readily and why?
Elements on groups 1,2,6 and 7 will most readily form ions because they only need to gain or lose 1/2 electrons to have a full outer shell
What do you use dot and cross diagrams for?
They show the number of electrons in an atom and how they change during a reaction
What type of atoms form covalent bonds?
Only non-metal atoms form covalent bonds with one another
Why do covalent bonds form?
They form covalent bonds in order to achieve a full outer shell
How do covalent bonds form and why are they so strong?
They form because two atoms share electrons, they are so strong because the nuclei of the atom is attracted to the electrons by electrostatic forces which are hard to overcome
Why don’t covalent bonds conduct electricity?
They do not have any delocalised or free moving particles that can carry charge within them
What is an allotrope?
Different structural forms of the same element in the same physical state
Define aqeous
It means ‘dissolved in water’
What are ionic compounds and what is their structure?
Compounds which only contain ionic bonds on the structure of a giant lattice
Why are ionic compounds so strong?
They have strong electrostatic forces in all directions
What are ions?
Charged particles
T/F: Metals lose an electron and non-metals gain electrons
True
What is a polymer and how are they bonded?
Polymers are long strings of repeating units which are joined by covalent bonds
Why do polymers have a lower MP and BP than giant covalent structures of ionic lattices?
This is because whilst the individual units are joined by strong covalent bonds, the whole structure is held together by weaker intermolecular forces
What are fullerene nanotubes and what are they used for?
These are tiny carbon cylinders which are great thermal and electrical conductors, they are tensile (don’t break when stretched); they are used in electronics to add strength without adding weight
What are fullerenes and what are they used for?
These are tubes of carbon in the shape of hexagons, pentagons or heptagons, these cages can form around other molecules and trap them inside (.e.g. tablets); they are great catalysts and effective lubricants
What is graphene and what is it used for?
This is just one layer of graphite meaning that it is one atom thick and 2D, ot can be added to materials to strengthen them without adding much weight; it can also conduct electricity thanks to delocalised electrons
What is graphite and what is it used for?
Each carbon forms three covalent bonds meaning there is one delocalised electron and graphite can conduct electricity, they form layers in hexagons and because there are no covalent bonds between layers it is soft and slippery
