Chapter 4 - Atomic Structure. Flashcards
where is the electron found in an atom?
where is the neutron found in an atom?
where is the Proton found in an atom?
In the shell
In the nucleus
In the nucleus
How do you find the proton and electron in the periodic table?
How do you find out ho many neutrons has an atom in the periodic table?
In the periodic table each element has something hat is called the the atomic number.
For to look for a neutron you subtract the atomic mass by the atomic number.
Eg: Lithium: has 3 protons and electrons. Then 7 (atomic mass) - 3 (atomic number) = 4 neutrons.
What are Isotopes?
An Isotope is when an atom has more neutrons than protons and electrons in an atom. Then the atoms start decay because they do not want so many neutrons.
What is an alpha particle?
GOOD NOTES page 60
An alpha particle is a nucleus that containing 2 neutrons and 2 protons. It is emitted by waves (Radiation) It has a 2+ charge, it has a mass of 4 (not in grams, no unit).
It’s extremely dangerous if you ingest. It is used in smoke alarms.
It can be stopped by paper, a sheet of aluminium and by a thick sheet of lead.
What is a Beta particle?
GOOD NOTES page 60
Beta is just a simple electron, it has a charge of -1. It doesn’t have any protons neither neutrons.
It’s a high energised electron. Used in monitor thickness. It can go through skin because it is very small.
It can be stopped by a sheet of aluminium and can be stopped by a thick sheet of lead.
What is gamma?
GOOD NOTES page 60
Gamma is a type of radioactive wave that does not contain electrons, neutrons and protons, this means that it has a charge of 0. It’s a high energetic photon*. It is used to treat gamma. It’s very hard to stop gamma radiation.
It can be stopped by a thick sheet of lead.
- a particle representing a quantum of light or other electromagnetic radiation. A photon carries energy proportional to the radiation frequency but has zero rest mass.
What is background radiation?
It’s ionising radiation that is always around us.
48% radon gas (From rocks, soil and building materials.) 14% gamma rays(from rocks and the soil) 11.5% food and drinks 12% cosmic rays (From the solar system) 14% X-rays 0.1% nuclear power stations/industries 0.2% falling from nuclear weapons that are being tested 0.2% other (mainly air travelling)
Nuclear Equations-
- alpha
- beta
Alpha: You have to take an atom from an element
Eg~ Uranium has 238 as atomic mass and 92 for atomic number. When it decays it make U 238/92 - He 4/2= Th 234/90
Beta: When it decays an atom from any element looses an electron.
Eg~ C 15/6 - e 0/-1 (electron) = N 15/7
What is a half-life?
A half-life is the average time that takes for half of all the nuclei present in a sample of a radioactive element to decay, or the time it takes for the count rate to halve.
The plum pudding experiment.
The Atomic model (the one that we use know)
The plum pudding is the model that Thomson created, his theory was that the objects were made out of protons and electrons. There was no existence of neutrons before.
The atomic model that we use today was created by Rutherford. The atom has protons an the electrons are in the shells. There is space in between the nucleus and the shells.
An experiment was been made and it consisted on shooting alpha particles to a thin sheet of gold. Then there was a detector that would surround the alpha gun and thin piece of gold that would detect the applause that was shot. Some rays returned because the alpha particles bounced back from the nucleus. Some went straight through in between the shells and the nucleus and others would bend a bit of the magnetic field.
