Unit 1 Flashcards
What is the kinetic particle model of matter
All matter is made up of tiny particles which are constantly moving
Thermal energy
Thermal energy is the total kinetic energy in an object
Temperature
Temperature is the average kinetic energy of the atoms making up an object
Kinetic energy
Kinetic energy is the energy of moving particles.
Heat
Heat is the transfer of kinetic energy between two systems of different temperatures.
Internal energy
Internal energy is the total energy in a system (both kinetic AND potential energy in a system)
Conduction
Conduction is the heat transfer between objects which are touching each other.
Convection
Convection is the heat transfer via fluids within a system
Radiation
Radiation is the transfer of heat between objects that aren’t directly touching (through EM waves).
What is a change in temperature due to?
The addition or removal of energy from a system.
Specific heat capacity
Specific heat capacity is the amount of energy required to increase 1kg of a substance by 1 degree Celsius.
Proportionality
the quality of corresponding in size or amount to something else.
Why does the temperature of a system remain the same during a state change?
During a phase change, the internal energy of the substance will change, however, the temperature is not changing because all of the added energy is going towards changing the bonds between particles.
Specific latent heat
Specific latent heat is the energy necessary to change the state of 1kg of a substance without changing the temperature.
What will energy transfers and transformations in mechanical systems result in?
Heat loss to the environment, so the amount of useable energy is reduced
Define efficiency
The ratio of useful work to the energy expended
What is the nuclear model of the atom
The nuclear model of the atom is characterised by a small nucleus surrounded by electrons
why do protons in the nucleus repel each other
The protons in the nucleus have a positive charge, meaning they repel one another
Define strong nuclear force
The strong nuclear force is a force that attracts protons and neutrons very close to one another, keeping them close together and overwhelming the repulsive forces between protons.
Explain the stability of a nuclide
The strong nuclear force acts only when protons and neutrons are close together, keeping them together and overwhelming the repulsive forces between protons as a result of electrostatic repulsion. thus, it is important to have a similar number of protons and neutrons to have a stable nucleus
Explain natural radioactive decay
natural radioactive decay occurs when the nucleus is unstable. the nucleus will often decay into smaller daughter nuclei and sometimes release a form of radiation
4 types of radiation that can occur
alpha decay, positive beta decay, negative beta decay, gamma decay
describe alpha decay
-nucleus will emit an alpha particle
- particle made of two protons and two neutrons bound together
-positive charge
-atomic weight of 4 amu
- slow and heavy
- can be stopped by a sheet of paper
describe beta positive decay
- nucleus emits a beta particle
- occurs when a proton in a nucleus spontaneously becomes a neutron
- positron and a neutrino emitted
- requires a sheet of aluminium to stop them
describe beta negative decay
- too many neutrons
- nucleus emits a beta particle
-occurs when an electron is emitted from the nucleus when a neutron spontaneously becomes a proton, an electron and an anti neutrino - requires a sheet of aluminium to stop them
describe gamma decay
- occurs when electromagnetic radiation is released from a decaying nucleus
- releases a gamma ray which travels at the speed of light
- neutrally charged
- atomic mass of 0
- it takes a slab of concrete to stop a gamma ray
define half life
half life is the time taken for half of a radioisotope to decay
