Chemistry history of atom + rate of reaction

Yr nine EOY

The plum pudding model was the first model of the atom - what did it look like?

It was a sphere of positive charge with negative electrons scattered inside of it

What experiment caused the model of the atom to be updated after the plum pudding model?

The alpha particles scattering experiment

What happened in the alpha particle scattering experiment?

In the alpha particle scattering experiment Rutherford blasted  positive alpha particles at a piece of gold foil 2 atoms thick

What were Rutherford’s observations and what did it prove?

Most particles went straight through - this proved atoms were mostly empty space. Some particles were deflected - proving the centre of the atom is positive. Sometimes a particle bounced straight back - proving the mass of the atom is concentrated in the centre.

What did the nuclear model look like?

The nuclear model contained a positive nucleus with electrons scattered inside the atom with a lot of empty space.

Shortly after the nuclear model was the Bohr model - what did that look like?

It contained a positive nucleus with electrons orbiting it at specific energy levels / shells

Which was discovered first protons or neutrons?

Protons

What do the halogens do to obtain a full outer shell?

They take one electron

Is it easier for the halogens to obtain a full outer shell going up or down the group?

It gets easier going up the group.

Why is Is it easier for the halogens to obtain a full outer shell going up the group?

This is because they gain more electrons going down the group. This makes the outer shell further from the nucleus. This makes the nuclear attraction weaker - making it more difficult going down the group to gain the electron.

What is rate of reaction?

Rate of reaction is how long it takes for a product to be completely formed or a reactants to be completely used up.

How do you calculate mean rate of reaction?

Total amount of product formed over total time

What are the factors that affect rate of reaction?

Temperature, surface area, concentration, pressure catalysts

How does temperature affect rate of reaction?

When the temperature is increased the particles gain more kinetic energy which makes them move around faster. This increases the chance of successful collisions.

How does surface area affect rate of reaction?

Increasing the surface area of solid reactants increases the number of particles that are exposed and therefore available to react. This means there will be a higher frequency of successful collisions.

How does concentration affect rate of reaction?

Increasing the concentration increases the number of articles available to react. Therefore increasing the rate of successful collisions.

How does pressure affect rate of reaction?

Higher pressure forces the gas particles closer together

How do catalysts affect rate of reaction?

Catalysts increase the rate of a reaction by providing an alternative reaction pathway with a lower activation energy, allowing more particles to collide successfully.

What is collision theory?

The theory that in order for particles to react they must successfully collide with each one another

What is activation energy?

Th minimum amount of energy needed for a reaction to start