Upgrade to remove ads
AQA GCSE Physics - Atomic Structure and Radiation
Terms in this set (86)
What is the approximate radius of an atom?
What three sub-atomic particles make up an atom?
Electrons, neutrons and protons
What is the mass and charge of a proton?
Mass = 1 charge = +1
What is the mass and charge of a neutron?
Mass = 1, charge = 0
What is the mass and charge of an electron?
Mass = very small, charge = -1
How big is the radius of a nucleus compared to the radium of an atom?
Where do you find most of the mass in an atom?
What two sub-atomic particles are found in the nucleus?
Protons and neutrons
Where do you find electrons?
In shells (energy levels)
In an atom, what can you say about the number of protons and the number of electrons?
They are the same
Why do atoms carry no overall charged?
Because the number of positively charged protons is the same as the number of negatively charged electrons, so they cancel each other out.
What is the atomic number?
The number of protons
What is the atomic mass?
The total mass of an atom
What is meant by relative atomic mass?
The average value of the atomic mass of all of the different isotopes of an atom
What is an isotope?
An element which has different numbers of neutrons.
Calcium has an electronic configuration of 2,8,8,2. What does this mean?
It has 2 electrons in the first shell, 8 in the second, 8 in the third and 2 in the fourth.
What is electronic configuration?
A way of writing the arrangement of electrons in energy levels in an atom.
What is the electronic configuration of calcium?
How are elements arranged in the periodic table?
In order of atomic number and put into columns with substance that have similar properties, known as groups.
What is a group on the periodic table?
What is a period on the periodic table?
How many groups are there?
Before the discovery of the electron, what did people think atoms were?
Tiny spheres which could not be divided
What theory was formed when electrons were discovered?
The plum pudding model
What is the plum pudding model?
It states that atoms are a ball of positive charge, with negative electrons embedded in it
What did the alpha particle scattering experiment lead to?
The nuclear model
Neils Bohr made a change to the nuclear model, what was it?
That electrons orbit the nucleus at specific distances
Who discovered neutrons in the nucleus?
What was fired at atoms in the alpha scattering experiment?
Alpha particles (2 protons + 2 neutrons)
What were alpha particles fired at in the alpha scattering experiment?
Why did some alpha particles deflect slightly in the alpha scattering experiment?
Alpha particles are positively charged and were repelled by the positive nucleus
Why did some alpha particles pass straight through the gold foil?
Because most of an atom is empty space
Why did some alpha particles bounce back the way they had came in the alpha scattering experiment?
They collided with the positive nucleus, showing that most of the mass is concentrated in the centre of an atom.
What is the nuclear model of the structure of the atom?
The mass of an atom is concentrated in the centre (nucleus) and that the nucleus has a positive charge
Why are atoms radioactive?
Some atoms are unstable and decay to become more stable.
What sort of process if radioactive decay?
A random process
What is activity?
The rate at which a source of unstable nuclei decays
What is activity measured in?
What is count-rate?
The number of decays recorded each second by a detector
What sort of radiation is represented by the symbol: α?
What sort of radiation is represented by the symbol: β?
What sort of radiation is represented by the symbol: γ?
What is an alpha particle?
Two neutrons and two protons, the same as a helium nucleus
What is a beta particle?
A high energy electron ejected when a neutron splits into a proton and an electron
What is gamma radiation?
Electromagnetic rations from the nucleus
What type of radiation is most penetrating?
What type of radiation is least penetrating?
What type of radiation is most ionising?
What type of radiation is least ionising?
What is alpha radiation stopped by?
5cm of air, paper, skin etc.
What are beta particles stopped by?
30-50cm of air, 3-5mm of aluminium
What is gamma radiation stopped by?
Thick lead absorbs most by not all of the radiation
What are nuclear equations?
Equations used to represent radioactive decay
How can an alpha particle be written in a nuclear equation?
The same as Helium
How can beta radiation be written as a symbol?
e, with a mass of 0 and an atomic number of -1
In alpha decay, what happens to the mass number of a radioactive isotope?
Drops by 4
In alpha decay, what happens to the
number of an isotope?
Drops by 2
How can you identify the new atom after a radioactive isotope as decayed?
Look it up using the atomic number on the periodic table
Radon has a mass of 219, what is its mass after alpha decay?
Radon has an atomic number of 86, what is its atomic number after alpha radiation?
What must be written at the end of every alpha decay equation?
Helium with a mass of 4 and an atomic number of 2
How does alpha decay affect the mass and charge of the nucleus?
Mass is reduced and charge is reduced.
How does beta decay affect the mass and charge of a nucleus?
It does not change the mass but it increases the charge of the nucleus
If carbon has a mass of 14, what would its mass be after beta decay?
If carbon has an atomic number of 6, what is the new atomic number after beta decay?
What effect does beta decay have on the mass?
It stays the same
What effect does beta decay have on the atomic number?
It increases by 1
How does the emission of gamma radiation affect the mass and charge of the nucleus?
It has no effect
What is half-life?
The time taken for the number of nuclei in a sample to half or for the count-rate from a sample to half
If Uranium has a half-life of 253 years, and our sample has 1000 atoms present, then how long would it take to reach 250 nuclei remaining?
506 years (2 half-lives)
What is radioactive contamination?
The unwanted presence of materials containing radioactive atoms on other materials.
Where does the hazard of contamination come from?
The decay of the contaminating atoms
What is irradiation?
The process of exposing an object to nuclear radiation. The irradiated object does not become radioactive
Who discovered energy levels/electron shells?
What is radioactive decay?
The process by which an unstable nucleus loses energy by emitting radiation
What is ionising radiation
radiation that knocks electrons off atoms creating positive ions
Explain how alpha radiation is used in smoke detectors
It ionises the air particles, causing a current to flow. If there is smoke in the air, it binds to the ions- meaning the current stops and the alarm sounds
What are beta emitters used for
To test the thickness of sheets of metal
What are the risks of ionising radiation?
They can enter living cells and ionise atoms/molecules inside causing tissue damage
The initial count-rate of a sample is 40cps. Calculate the decline in count rate, as a ratio, after three lives
Give 3 sources of background radiation
1)Naturally occurring unstable isotopes-in AIR,FOOD etc
3)Fallout from nuclear explosions/waste
What are the uses of alpha radiation?
What are the uses of beta radiation?
Used as medical tracers-pass through skin, and weakly ionising
What are the uses of gamma radiation?
Kills cancerous cells, and sterilises medical equipment
What is nuclear fission?
The splitting of a heavy unstable nucleus to form two lighter, stable nuclei and emits neutrons to create a chain reaction
What is nuclear fusion
Two light nuclei collide at a high speed to create a larger, heavier nucleus
YOU MIGHT ALSO LIKE...
Unit 3 CHEM study guide
Radiologic science for technologist ch 2&3
Atomic Structure Revision
UNIT 5 - ATOMIC THEORY
OTHER SETS BY THIS CREATOR
GCSE AQA Geography Paper 2
GCSE AQA Biology Topic 2
GCSE AQA Chemistry Topic 1
GCSE AQA Biology Topic 1
OTHER QUIZLET SETS
Sociology exam 1
social studies chapter 7,8
Geo Exam 2 Chap 5 Book Q
UW History Final