Particle model of matter Flashcards
Solids - arrangement of particles
particles are very close together
- particles are arranged in a regular pattern
- particles vibrate but they do not move from place to place
liquids-describe the arrangement of particles
- particles are close together
- particles are not arranged in a regular pattern
- particles can move around each other
Gas- arrangement of particles
- particles are very far apart
- particles are not arranged in any pattern
- particles are moving very rapidly
what is density
Density of a material tells us the mass for a given volume
what is the density of a brick like
A brick has very high density. it has lots of mass packed into its volume
what is the density of a polystyrene block like
the density for a polystyrene block is low. it has a lower mass packed into its volume
what is the equation for density and the units
density
p kg/m^3 = mass (kg) / volume (m^3)
a block of wood has a mass of 150kg and a volume of 0.3m^3. calculate the density
150/0.3=500kg/m^3
solids usually have a very high density why?
solids have a very high density because the particles are very closely packed together solids have lots of mass for their volume.
liquids also usually have high density why?
liquids usually have high density because the particles are close together, liquids have alot of mass for their volume
gases usually have a low density why?
gases have a low density because the particles are far apart so gases only have a small mass for their volume.
there is an exception: polystyrene is a solid with a low density why?
this is because polystyrene has a very open structure and is full of air spaces. it has a small mass for its volume.
required practical density: calculating the density of regular and irregular objects definition of density: density of a material tells us the mass for a given volume
units for density= kg/m^3
regular objects have dimensions we can easily measure with a ruler
irregular objects- cannot easily measure dimensions
regular objects density- first determine the mass using a balance.
next work out volume by using a ruler to measure length of each side. volume of a cube= length of side^3
why cant we measure density of irregular objects using a ruler
because we cannot easily measure the dimensions instead we have to determine the volume using displacement.
how to determine the density of irregular objects
first, measure mass of object using a balance.
fill a eureka can with water. eureka can has a spout so that water can flow out through the spout.
place the object in water. this will cause water to be displaced as it will flow through the spout
collect water in a beaker and then transfer to measuring cylinder to measure the volume of water displaced.
once you have determined the volume, use it to calculate the density of the object using the equation
density kg/m^3= mass (kg)/volume (m^3)
key point- the volume of water displaced is the volume of the object.
what types of energy do particles have
two types: k, p
-kinetic energy= all these particles have kinetic energy (due to particles movement)
potential energy= ( intermolecular forces or chemical bonds if they are a molecule)
what is the definition of internal energy
internal energy is the total kinetic energy and potential energy of all the particles ( atoms or molecules) that make up a system.
total kinetic energy and potential energy of all the particles that make up a system
what happens when we heat a solid
if we heat a solid, we are increasing the internal energy. at some point the solid can turn into a liquid (melting)