Particle model of matter Flashcards
(98 cards)
To convert g/cm3 to kg/m3 you have to:
Multiply the g/cm3 value by 1000
per cm3 to per m3, multiply by 1,000,000 ( m3 = 1,000,000 larger)
What is the equation to calculate density?
Density = mass/volume
Unit for density?
kg/m³
Unit for volume?
m³
What is density?
A measure of how much mass a substance has per unit of its volume.
How would we calculate the density of a liquid experimentally?
-Place an empty measuring cylinder on a balance
-Zero the balance
-Pour the liquid into the cylinder
-Record it’s volume
-Record the mass of the liquid
-Use the density equation
How can we get more accurate estimates of density of a liquid?
Measure a larger volume.
Take multiple measurements to identify any anomalies and calculate a mean.
How would we calculate the density of a regular solid experimentally?
-Place the solid on a balance and measure the mass
-Find volume by measuring and then multiplying its length, width, and height
-Use the density equation
How would we calculate the density of an irregular solid experimentally?
-Place the solid on a balance and measure the mass
-Measure the volume by adding the solid to a Eureka can filled with water.
-Use the density equation
What is the symbol equation for density?
ρ = m/V
What can the particle model be used to explain?
-The different states of matter
-Differences in density
What is the arrangement and energy of the particles in a solid like?
-Particles are arranged neatly into ordered rows
-Particles are all closely packed and touching
-Particles vibrate in a fixed position (less kinetic energy)
Why are solids denser than liquids and gases?
The particles in solids are more tightly packed, with less space between them, than liquids or gases (the volume of solids is small).
So, density is higher because density is defined as mass per unit volume.
Why are particles in a solid in a regular lattice structure?
Strong forces of attraction between particles/bonds holds them close together.
Why are substances in the gaseous form less dense than liquids or solids?
The particles are widely spaced so the same number of particles occupies a larger volume than in a liquid or solid.
This leads to a lower density as density is defined as mass per unit volume.
Density of a liquid? (compared to a solid)
In a liquid, the particles are a bit more spread out, so the volume is slightly larger, resulting in a slightly lower density than a solid.
How do changes of state differ from chemical changes?
-They are physical changes
-The material recovers its original properties if the change is reversed
What is the arrangement and energy of the particles in a liquid like?
-Particles are arranged randomly
-Particles are less tightly compact than in solids
-Particles can move past each other (randomly)
What is the arrangement and energy of the molecules in a gas like?
-Molecules are arranged randomly
-Molecules are spread far apart
-Molecules are constantly moving with random motion (deflected randomly)
Why do molecules in a gas move around constantly, and very quickly?
They have a lot of kinetic energy.
What happens if we heat up a solid?
The particles gain more kinetic energy and so vibrate more.
Eventually, they will gain enough energy to overcome the strong forces of attraction holding them together.
This allows particles to break free of the solid lattice - ‘melting’.
This is known as the ‘melting point’.
What happens if we heat up a liquid?
The particles gain kinetic energy and so move around faster.
This weakens the forces of attraction holding the particles together.
At the ‘boiling point’, the particles have enough energy to break away from the forces all together - ‘evaporating/boiling’.
So, the liquid evaporates/boils into a gas.
What happens if we heat up a gas?
The particles gain kinetic energy and so travel faster.
If the container is expandable, gas will expand and so volume will increase
If the container is fixed, pressure will increase.
What happens if we cool down a gas?
The particles will lose kinetic energy and so won’t have enough energy to overcome the forces of attraction between them.
Bonds will start to form between the particles, condensing the gas in to a liquid.