Atomic Structure And Electrostatics Flashcards
What are the particles in the atom?
Proton
Neutron
Electron
Location of each particle in the atom
Electron-Orbiting nucleus
Proton-Nucleus
Neutron-Nucleus
Charge in each particle in the atom
Electron=-1 (only one left)
Neutron=0 (neutral)
Proton=+1 (plus, p)
Mass of each particle in the atom
Electron=1/2000
Neutron=+1
Proton=-1
True or false: the atom is mostly empty space
True
How does Rutherfords experiment tell us that the atom is mostly empty space?
When Rutherford fired the alpha particles of the gold foil, he found that most of the alpha particles pass straight through the foil and came out the other side this showed Rutherford that the atom could not be like a plum pudding, it must actually be made of mostly empty space so the alpha particles did not get deflected by anything.
When and where did Rutherford carry out his experiment?
In the early 1900s in the university of manchester
What did physicists think about the atom prior to the Rutherford experiment?
Before Rutherford did his experiment, physicist of the atom has been rather like a plum pudding. J.J Thompson had already shown that there are small particles in the atom has a negative charge. These are the electrons. As they knew that the overall atoms had a neutral charge, they knew that there must be a positive charge present in the atom cancel out the negative charge. Thompson imagine that the negatively charged electrons bracket (the plum) were embedded in a sphere of positive charge (the pudding)
What was the conclusion from the experiment?
Most of the alpha particles pass straight through so the atom must be mostly large gaps
What do we know about the atom now?
We now know that the positive charges (the protons) are at the centre of the atom. These are together with the neutrons. We call this part of the atom in the nucleus. Orbiting around the edge are the negative charges (the electrons). In between the nucleus and the electrons are a large amount of empty space.
What happened in the experiment?
An alpha particle contains two protons and two neutrons, therefore it has a positive charge. When the alpha particle gets near to the positive charge in the atom it gets repelled and comes back towards you.
Why do objects become charged?
Because electrons have a negative charge, when they are added to an object, it becomes negatively charged. When electrons are removed from an object, it becomes positively charged. Electrons are the only particles in the atom that can move
Describe how objects become charged.
When you rub two objects together, you either gain or lose electrons. An electrical charge is created when electrons are transferred to or removed from an object.
Uses of electrostatics
- Photocopiers: Photocopiers use static electricity to attract the small particles of ink onto the paper in the right places.
- Electrostatic precipitators: To clean small particles from smoke before it leaves an industrial chimney, a machine called an electrostatic precipitator will use static electricity to attract the particles.
- Insecticide: insecticide sprays from aircraft can be electrostatically charged so that they cover a large area. With this method there is less risk that some of the spray will blow away or fall unevenly. The droplets of insecticide are all given the same static charge as they leave the aircraft.
Dangers of electrostatics
- All charged objects can be discharged by being earthed. This may happen safely by connecting them to the earth with a conductor.
- It is dangerous when you touch something with a large electric charge on it. The charge will flow through your body causing an electric shock.
