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Flashcards in TOPIC 4 Deck (46):

What does a change of state require



Why are there flat spots on the heating graph

Energy is being transferred by heating but not being use to change the temperature


When melting and boiling a substance energy is getting put in what the energy used for

Breaking intermolecular bonds rather than rising the temperature


What is the energy needed to change state of substance

Latent heat


When a substance is condensing or freezes bonds form between the particles
What energy is released

The internal energy decreases


What is specific latent heat of a substance

The amount of energy needed to change 1kg of it from one state to another without changing its temperature


When a substance cools what is the SLH

The energy is released by a change in state


Is specific latent heat the same for every substance

It is different for different materials and for changing between different states


What is the specific latent heat for changing between solid and liquid (melting and freezing)

The specific latent heat of fusion


What is the specific latent heat for changing between a liquid and gas (evaporating, boiling or condensing)

It is the specific latent heat of vaporisation


What is the formula for when a substance changes

Energy (E) = mass (m) x specific latent heat (L)
Energy is given in joules (j) mass is in kg and SLH is in j/ kg


What three radioactive substances of ionising radiation from their nuclear

Alpha, beta and gamma radiation


What is ionising radiation

Radiation that knocks electrons off atoms, creating positive ions. The ionising power of a radiation source is how easily it can do this


What is alpha radiation

It is when alpha particles is emitted from the nucleus and a-particles is two neutrons and two protons


What are alpha particles

Helium Nucluei


What are beta particles

Is a simply a fast- moving electron released by the nucleus. But beta particles have virtually no mass and a charge -1.


What type of ions are alpha and beta

Alpha are strongly ionising and beta particles are moderately ionising they penetrate moderately far into materials before colliding


When is a neutron in the nucleus has turned into a proton

For every beta particles emitted


What are Gemma rays

They are waves of electromagnetic radiation released by the nucleus


What do gamma rays do

Penetrate far into materials without being stopped and will travel a log distance through air. They collide with atoms. Eventually they hit something and do damage


What can gamma rays be absolutely by

Thick sheets of lead or metres of concrete


What does a nuclear equation show

Radioactive decay by using element symbols


What are radioactive decay written like

Atom before decay ➡️ atom after decay + radiation emitted.


What is the golden rule to remember

The total mass and atomic numbers must be equal on both sides


How any protons and neutrons are alpha particles made from



How does an alpha decay decreases the charge and mass of the nucleus

A proton is positively charged and a neutron is neutral, so the charge of the nucleus decreases and


What are gamma rays used for

They are a way of getting rid of excess energy from the nucleus
This means that there are no change to the atomic mass or atomic number of the atoms


What do radioactive substances give out

A radiation from the nuclei of their atoms- no matter what


What is the radiation measured in

With a Geiger- Müller tune and counter which records the count-rate


What is the half-life

The amount of radiation emitted by a source to halve, this is known as the half-life


Why do we use the idea of half-life

The problem with trying to measure this is that the activity never reaches zero, which is why we have to use the idea of half- life to measure how quickly the activity drops off


What can half-life be described as

As the time taken for the activity to fall to half of its initial value


How can half-life be measured from

By using a graph


How is the half life found on a graph

Time internal on the bottom axis corresponding to a having of the activity on the vertical axis


What damage can ionising do

They can enter living cells and ionise atoms within them. This can damage the cells (cancer) it kill them off completely so it’s important to know the precautions to take when taking when working with any sources of radiation


How are objects near a radioactive source

They are irradiated by it. This means they are exposed to it


How can the effect of irradiation be reduced

Keeping sources in lead-lined boxes and standing behind Barrie’s when using sources are common ways of reducing the effects of irradiation


How else is radiation kept controlled

The source may be in a different room and remote-control arms are used to handle it


How are objects contaminated from radioactive particles

Unwanted radioactive atoms get onto or into an object, the object is said to be contaminated


When you contaminated how dangerous it is

Because radioactive particles radiation could cause you harm


What can be done so a person doesn’t get contaminated

Gloves and tongs should br used when handling sources to avoid particles getting stuck to your skin or under your nails
Protective suits to stop then breathing in particles


How are beta and gamma sources dangerous

They can penetrate the body and get to delicate organs


How is alpha less dangerous

Because it does penetrate the skin and is easily blocked by a small air gap


Which type of radiation is more concerning



How are alpha source are more dangerous inside the body

Because they damage in a very localised area. So contamination, rather irradiation


Why is it important that we have a better understanding of the different radiation affecting our bodies

They better we an protect ourselves when using them. The data is peer-reviewed and can quickly become accepted