C3: Structure & Bonding Flashcards
What happens in metallic bonding?
The particles which are atoms share delocalised electrons
How are ionic compounds held together?
By strong electrostatic forces of attraction between the oppositely charged ions.
What are ionic compounds always?
Giant
What large molecules have covalent bonds?
Polymers
What are 2 giant covalent structures?
Diamond and silicon dioxide
What does the amount of energy needed to change a substances state depend on?
The strength of the forces between the particles
What is the relationship between melting and boiling point, and the strength of the forces between particles?
The stronger the forces, the higher the melting and the boiling point
What are 3 limitations of the simple model?
The model has no forces, all the particles are represented as spheres and that they are solid
What are 2 properties of ionic compounds?
They have high melting and boiling points due to the large amount of energy needed to break the strong bonds and they conduct electricity when molten or dissolved due to ions being free to move around and carry charge
What are 3 properties of small molecules?
Gases or liquids, so low melting and boiling points, weak intermolecular forces (which break when heated) and do not conduct electricity as the molecules do not have an overall charge
What does each carbon atom in diamond form?
4 covalent bonds
What are 3 physical properties of diamond?
Hard, have high melting and boiling points, and do not conduct electricity
What does each carbon atom in graphite form?
3 covalent bonds
What shape are the rings in the layers of graphite?
Hexagonal
What is graphene useful for?
Electronics and composites
What are fullerenes?
Molecules of carbon atoms with hollow shapes
What shape was the buckminsterfullerene?
Spherical
What shape are carbon nanotubes? What are they useful for?
Cylindrical. Electronics, nanotechnology and materials
What are the diameters of nanoparticles?
Between 100 - 2500nm
What are some applications of nanoparticles?
Suncream, deodrants and catalysts
What type of structures do metals have?
Giant
Why are metals good conductors of electricity? Why are they good conductors of thermal energy?
Because they have delocalised electrons that carry electrical charge. This is because energy is transferred by the delocalised electrons
Why are the elements in group 3, 4, and 5 not considered ions?
Because they would have to lose or gain 3 or 4 electrons, which requires lots of energy
When do you know which way reactants go in half equations?
If the atom is becoming a positive ion and loses electrons, the electron is on the right
What is a disadvantage of displayed formulas when represent covalent bonds?
They don’t show the 3D shape of the molecule
What is a disadvantage of 3D model when representing covalent bonds?
Hard to predict what shape the molecule will make
What are examples of small molecular forces?
Ammonia, chlorine, water and methane
Why does the boiling point increase as you go down group 7?
Because the molecules get larger, so there are more intermolecular forces present
What are allotropes?
Different structural forms of the same element in the same physical state
Why is graphite soft?
No covalent bonds between layers, so can slide over each other
Why are nanoparticles seen to be dangerous?
They have a large SA:Vol ratio, so if a spark happened, it would be very dangerous for a large quantity. Also, if they’re used more and more, that would be found in the atmosphere easily, which could damage lungs if breathed in
