C2.3 Flashcards
Why can carbon form a vast array of organic compounds?
Because it forms four covalent bonds, creating families of similar compounds, chains, and rings.
How does graphite’s structure affect its properties?
Layers of hexagonal rings with weak intermolecular forces allow layers to slide, making it soft and slippery. It conducts electricity due to delocalized electrons.
What are the key properties of diamond and why?
Very hard, high melting point, and does not conduct electricity due to each carbon being covalently bonded to four others.
What affects the temperatures at which substances change state?
Strength of chemical bonds and intermolecular forces.
What are fullerenes and their significance?
Molecules of carbon atoms with hollow shapes, such as Buckminsterfullerene (C60). Used in nanotechnology and electronics.
How does energy transfer relate to changes of state?
Energy is transferred to melt/boil and transferred from the substance to condense/freeze.
Describe graphene and its uses
A single layer of graphite, known for strength and conductivity, useful in electronics and composites.
Why do ionic compounds have high melting/boiling points?
Due to strong electrostatic forces between ions, making them harder to overcome.
How can you predict the state of a substance at a given temperature?
Below melting point: Solid
Between melting and boiling point: Liquid
Above boiling point: Gas
What is the size of nanoparticles, and how do they compare to atoms?
1–100 nm across, smaller than fine particles (PM2.5) and coarse particles (PM10).
How do bond types relate to bulk material properties?
Ionic compounds, simple molecules, covalent structures, polymers, and metals differ due to bond strength and arrangement.
Why do nanoparticles have unique properties?
Their high surface area to volume ratio makes them more reactive and useful in catalysts, sensors, cosmetics, and electronics.
What are some uses of nanoparticulate materials?
Catalysts, selective sensors, stronger building materials, cosmetics, lubricant coatings, and small electrical circuits.
What are the possible risks of nanoparticulate materials?
Unknown long-term risks, potential medical issues with interaction in cells.
What type of bonds does diamond have?
Strong covalent bonds where each carbon atom is bonded to four others.
Why can graphite layers slide over each other?
There are no covalent bonds between layers, only weak intermolecular forces.
What shape are carbon atoms arranged in fullerenes?
Hexagonal rings, sometimes with rings of five or seven atoms.
What makes graphite similar to metals?
It has delocalized electrons that allow it to conduct electricity.
Why doesn’t diamond conduct electricity?
It has no free or delocalized electrons.
Why are carbon nanotubes useful?
They have high strength and conductivity, useful for nanotechnology and electronics.
How does graphene’s structure differ from graphite?
Graphene is a single layer of graphite, extremely thin and strong.
What is the structure of carbon nanotubes?
Cylindrical fullerenes with high length-to-diameter ratios.
What happens when energy is transferred to a substance?
It can cause melting (solid to liquid) or boiling (liquid to gas).
What happens when energy is transferred from a substance?
It can cause condensing (gas to liquid) or freezing (liquid to solid).
Why do macromolecular substances have high melting points?
Because breaking covalent bonds requires a large amount of energy.
How do ionic bonds affect boiling and melting points?
Strong electrostatic forces make them higher compared to simple molecules.
Why do simple molecular substances have low melting points?
Only weak intermolecular forces are overcome, not covalent bonds.
What happens to surface area to volume ratio as particle size decreases?
It increases significantly, making materials more reactive.
Why are nanoparticles more effective as catalysts?
Larger surface area allows more reactions to occur simultaneously.
Give two examples of nanoparticles in everyday products.
Sunscreen (no white marks) and deodorant.
What is PM2.5?
Fine particles with diameters between 100 and 2500 nm.
What is PM10?
Coarse particles with diameters between 1 x 10⁻⁵ m and 2.5 x 10⁻⁶ m.
How could nanoparticles improve building materials?
They could make them stronger and lighter.
Why are lubricant coatings with nanoparticles useful?
They reduce friction, ideal for artificial joints and gears.
How are nanoparticles used in electronics?
They conduct electricity, suitable for small electrical circuits.
What are the concerns about nanoparticles in medicine?
Their interaction with cells is not fully understood, posing potential risks.
