Physics P2 Atomic Structure
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?- Created by: Dominic Hayward
- Created on: 17-05-13 15:57
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- Atomic Structure
- Atomic Structure
- An atom is made from a nucleus and surrounded by electrons
- Isotopes have the same number of protons but a different number on neutrons
- Atoms contain three sub-atomic particles called protons, neutrons and electrons. Protons and neutrons are found in the centre of the atom and the electrons are arranged in energy levels around the nucleus.
- Protons have a relative mass of 1 and a charge of +1. Neutrons have a relative mass of 1 and a charge of 0. Electrons have a relative mass of almost zero and a charge of negative -1.
- An ion is formed when the outer shell of electrons are full. If an atom loses electrons, it becomes positely charged, and vice versa.
- Plum pudding model is a sphere of positive energy with negatively charged electrons dotted around
- Rutherford scattering experiment fired alpha particles at a gold leaf and discovered that some were deflected.
- Nuclear Radiation
- Backgroun radiation is all around us, and most comes from natural sources.
- Natural sources include cosmic rays, rocks and living things.
- Human activity has added to radiation from x-rays and power stations
- We can detect radiation by using photographic paperas it turns darker when absorbing radiation.
- A geiger-muller tube also detects radiation by sending a pulse everytime it is detected.
- Alpha radiation consists of helium nuclei
- Alpha is the least penetrating-blocked by a peice of paper
- Gamma radiation is released with the other 2 types of radiation and is a long wavelength
- Gamma is the most penetrating but is stopped by lead.
- Beta radiation consists of high energy electrons from a neutron splitting into a proton and electron.
- Beta can go through air and paper but not aluminium
- Gamma radiation is released with the other 2 types of radiation and is a long wavelength
- Gamma is the most penetrating but is stopped by lead.
- Beta radiation consists of high energy electrons from a neutron splitting into a proton and electron.
- Beta can go through air and paper but not aluminium
- Alpha is positevely charge, beta is negatively charged and gamma is neutral.
- Alpha and beta can be deflected be magnetic fields but gamma cannot.
- Radiation can affect dna and if so,can become cancerous.
- If the source of radiation is outside the body then alpha is the most dangerous due to its size
- inside the body, gamma and beta are damaging due to the high penetration level.
- Half lifes change one element into another and is how long it takes for half the nuclei to de-compose.
- Uses of radiation:smoke detectors, sterilising and killing cancer cells.Doctors use them as tracers due to some elements having a short half life. They can also be used for modelling thickness of materials.
- Alpha decay is where the mass number decreases by 4 and atomic number decreases by 2.
- In beta decay, the atomic number stays the same but the atomic number increase by 1.
- Backgroun radiation is all around us, and most comes from natural sources.
- Fission and Fusion
- Fission
- This is where the nucleus splits.
- First a neutron is absorbs by a uranium nucleus. Then it splits and another neutron is fired and the process repeats.
- This process creates energy
- First a neutron is absorbs by a uranium nucleus. Then it splits and another neutron is fired and the process repeats.
- This is where the nucleus splits.
- Fusion
- Nuclear fusion is joining two nuclei to make a larger nucleus and energy is released when this happens
- Eg hydrogen 1 and hydrogen 2 making helium 3
- Nuclear fusion is joining two nuclei to make a larger nucleus and energy is released when this happens
- Fission
- Atomic Structure
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