C1.1.3 - Limitations of the Particle Model Flashcards
What are atoms?
The smallest particles that make up a substance
What element has the smallest atom of all?
Helium atoms
If hydrogen only has 1 proton and 1 electron, Why is helium smaller when it has 4 times the atomic mass?
The two protons in helium pull the electron shell closer than just one does in hydrogen
What is the diameter of helium atoms?
62pm (62x10 to the power of -12)
Why is it difficult to draw particle diagrams of the gas state to scale?
In reality, the distance can be up to 55 times the diameter of the atom, which would be impossible to display on a small diagram
What are the forces between particles?
Electrostatic forces of attraction
What happens to the electrostatic forces when particle move further away from each other?
They get weaker
In which state are the electrostatic forces strongest?
Solid
In which state are the electrostatic forces weakest?
Gas
What are the limitations of the particle model?
The forces between particles, the size of particles and the space between particles are not taken into account
What happens to the volume of a substance when it melts?
It increases
Why does the volume of a substance slightly increase when melting?
Some of the forces of attraction are overcome and the particles can move around each other
What happens to the density of a substance when it melts?
It decreases
There is one exception to this where, when this melts, the density increases. What is this?
Ice, as it has a lattice structure meaning the particles move closer when melted
What is the one substance which decreases in volume when melted?
Ice, as it has a lattice structure rather than every particle being next to each other
