What are the 3 principles of John Daltons atomic Theory?
- All matter is made up of very small identical particles called atoms.
- All atoms are invisible and cannot be broken down into simpler particles.
- Atoms cannot be created or destroyed.
What are cathode rays?
Streams of charged particles coming form a negative electrode or cathode.
What happens when an object is placed in the path of the rays in Crookes apparatus?
It would cast a shadow of the object at the far end of the tube.
How were electrons discovered?
J.J Thomson discovered that the rays from crooks experiment were attracted to a positive plate proving that they were negative.
What is the equation for the charge mass of the electron?
e/m (charge to mass ratio)
Explain Thomson’s “plum pudding” model of the atom.
He proposed that the atom was a sphere of positive charge with negative electrons embedded in it at random to keep the atom neutral.
What were the three main results of the Rutherford discovery of the nucleus experiment?
- Majority of the alpha particles went strait through the gold foil proving most of the atom is empty space.
- Some alpha particles were deflected as they were repelled by the positive charge of the nucleus.
- Others bounced back after hitting the nucleus.
What are alpha particles?
Alpha particles are Helium nuclei with a double positive charge (4/2He^2+).
In the discovery of the proton what happened in the case of smaller atoms when bombarded with alpha particles?
Small positive particles were released calling them protons.
In the discovery of the proton what happened in the case of larger atoms when bombarded with alpha particles?
Nothing happened because the nucleus had a much stronger repelling effect due to a stronger positive charge.
How was the discovery of the neutron made?
Chadwick bombarded beryllium with alpha particles and found neutral particles were being emitted from the nucleus which were called neutrons.
What are the three main differences between the modern periodic table and the Mendeleev’s table?
- Change form element ordering by atomic weight to atomic number.
- Addition of more elements.
- No longer gaps in the table.
What is the relative mass of an electron?
1/1836
What is the relative mass of a proton?
1
What is the relative mass of a neutron?
1
What is the relative charge of an electron?
Negative (-1)
What is the relative charge of a proton?
Positive (+1)
What is the relative charge of a neutron?
Neutral (0)
What is the location of an electron?
Orbiting the nucleus.
What is the location of a proton?
In the nucleus.
What is the location of a Neutron?
In the nucleus.
What is the atomic number of an atom?
The atomic number of an atom is the number of protons in the nucleus.
True or False, in a neutral atom the number of protons is equal to the number of electrons.
True
What is Given the symbol Z?
The atomic Number.
