P1 Flashcards
What was Dalton’s model of the atom
He said atoms were small indestructible spheres where all atoms in an element where the same and each element has its own atoms
What was JJ Thomson’s model and how did he create it
He discovered cathode rays are made of particles less than 1-thousandth the size of a hydrogen atom.
He called these electrons
He decided electrons where embedded inside a positive mass (like a plum pudding) as they were negative and an atom was neutral.
Plums represented the electrons and the ‘pudding was the positive mass’
He believed the mas could be a solid or like a cloud
What was the Rutherford model
Ernest rutherford discovered some particles emit alpha particles
He fired these alpha particles at gold foil expecting them all to pass through, but some came back
To explain this he said an atom has a positively charged nucleus with electrons orbiting it
What did niehls bohr do
He stated that electrons orbited the nucleus in fixed electron shells
With Rutherford’s model the electrons would eventually crash into the nucleus
How big are atoms
1×10^-10m
What is density
How much mass can be found in a specific volume.
Mass ÷ volume
How do you calculate density
Density (kg/m3) ° mass(kg) ÷ volume (m3)
Which is denser, a solid liquid or gas
The solid is the most dense, as the particles are packed together more tightly, allowing there to be more particles in the same area
What is conservation of mass
You have to add or remove mass for it to change. Particles will not appear or disappear during changes of state.
What is temperature
A measurement of the average kinetic energy of the particles in a material. It does not depend on the amount of material you have
What is kinetic energy / kinetic store
The energy associated with a kinetic store
A energy in a kinetic store is associated with a moving object calculated with Ke = 1/2mv^2
What is 0K in °C and what is 0°C in
K = kelvin
°C = degrees Celsius
0k = -273°C
0°C = 273K
If a temperature changes by 1°C it changes by 1 kelvin
What is the difference between thermal energy and temperature
Temperature tells you the average Ke of particles
The energy in a thermal store is measured in Joules and depends on how fast the particles are moving and vibrating.
INDIVIDUAL PARTICLES DO NOT GET HOTTER
What happens when you heat something up
Heating can
Change the energy stored within the system to increase temperature
Produce a change of state
Make chemical reactions occur
What is a physical change
Change, such as change in state, that does not result in a new substance being made - irreversible
What is a chemical reaction
Process in which substances react to form different substances
What factors are important to raise the temperature of an object
The temperature rise
The type of object (e.g. good / bad conductor)
The mass of the material
What is specific heat capacity?
The energy needed to raise the temperature of 1kg of a material by 1K (or 1°C )
What is internal energy
The energy of a system because of the arrangement and movement if particles within it
What energy does heating an object increase?
Its internal energy - relating to motion vibration and arrangement of the particles in the object
How do you calculate with specific heat capacity
Change in the thermal energy (J) =
Mass (kg) × SHC (J/Kg°C) × change in temperature
Why does specific heat capacity (SHC) make a difference?
It tells you how resistant a material is to a change in temperature.
Objects like saucepans that need to heat up quickly are made from materials with low specific heat capacities, as less energy is needed to heat up the material
