STATES AND MATTER Flashcards
What is Matter
Matter is everything around us that has mass (weight) and takes up space, we say that matter has mass and volume.
States of matter
A physical property is something you can observe about an object or substance, which can be measured
Fixed shape
Fixed volume
Can’t be compressed
Solids
No fixed shape Fixed volume Can be poured Can’t be compressed (not by much anyway)
Liquids
No fixed shape
No fixed volume
Diffuses (spreads out) quickly
Can be compressed
Gases
What is Matter Made of?
Particles! They are the very small parts that make up matter.
The Particle Models
A Scientific Model isn’t a physical thing, it’s an IDEA. It is a ‘simple’ way of thinking about the world that helps us to understand it.
Kinetic Particle Theory
This model explains the behaviour of matter by looking at the arrangement of particles in the matter. It explains the three states of matter, solids, liquids and gases.
Solids
in solids, particles are close together and vibrate on the spot.
The particles in a solid do not have much energy, which is why they are not moving very much. However they don’t have no energy, just very little. (particles cant ever have zero energy, for complex reasons)
Liquids
In liquids, particles are close together and vibrate enough that they aren’t stuck in place but can slide around and over and past each other. They aren’t vibrating enough to bounce up or jump anywhere.
The particles have more energy than in a solid. They have enough energy to break the bonds (or connections) between each other, which is how they can move around. They don’t have enough energy to leave the container.
Gases
In gases, particles are far apart and move freely.
Most gases are invisible, but they also share common particle properties. The gas particles are not bonded together allowing them to move around freely. Heating a gas causes the particles to move around even faster, but it stays a gas. (until really hot)
In gases, particles are far apart and move freely.
Each particle has lots of energy, enough for it to not just break apart from the other particles, but also for it to be able to leave the container and fly off.
Changes of States
To change from solid to liquid to gas we need to add energy in the form of heat.
By adding energy we are increasing particle movement.
To change from gas to liquid to solid we need to take away energy in the form of cooling.
By taking energy away we are decreasing particle movement
Solid to Liquid
To change a solid (e.g. Ice) to a liquid (eg. Water), heat energy must be added to make the particles vibrate more (and more and more). Eventually the particles have enough energy
to separate, and the
solid melts.
The temperature at which something turns from solid to liquid is calling its melting point.
Liquid to Solid
The reverse of melting is freezing. When a solid loses energy, the vibration of the particles lessens and the bonds between the particles are once again strong enough to keep them in a fixed position.
The freezing point is the same temperature as the Melting Point.
Liquid to Gas
A liquid changes into a gas when heat speeds up the particles enough that the fast movement completely breaks the bonds between the particles. They fly apart, changing state of the material to a gas.
The process od going from liquid to gas is called evaporation
The temperature this happens at is known as the boiling point
Gas to Liquid
The opposite od evaporation is condensation. Condensation happens when gas particles lose heat, slow down, and turn into liquid. When you breathe out on a very cold day, the water vapor in your breath (a gas) condenses to form tiny droplets of water. The Condensation Point is the same temperature as the Boiling Point, but when cooling down.
Solid to Gas
Sublimation is a much less common change. Sublimation occurs when a solid absorbs heat and changes directly to a gas without melting and going through the liquid stage. An example of sublimation is dry ice.
Gas to Solid
The opposite of sublimation is … sublimation, although its also known as DE sublimation or deposition.This is when a gas loses heat and changes directly to a solid without being a liquid first.
An example of DE sublimation is frost forming on plants on a cold night – the water vapor (gas) in the air goes straight to solid ice on the leaves … for complicated reasons.
Expansion and Particles
A substance may change state when cooled or heated. If a substance doesn’t change state, then its particles will still move faster or slower – its temperature will change - and it will either expand (get larger) or contract (get smaller).
Expansion (getting larger on heating) or contraction (getting smaller when cooled) is explained by the Particle model of matter
DENSITY
The particles in a substance can have a small or large mass and can be packed tightly together or spread out
The density of a substance is the amount of matter (particles) packed into a given volume.
For example, Styrofoam box is less dense than a metal box because the particles in Styrofoam have a small mass and are not close together.
OR, the particles could be the same distance apart, but each particle is heavier or lighter. For example, lithium is a metal that floats, aluminium sinks but is still light, and a lead is a metal that sinks straight to the bottom of most things.
WHAT DOES DENSITY MEAN?
We know it’s the amount of mass in a given volume, but… so what? Density tells you if something will float or not. If an object is less dense, it will sit on top of a liquid. If it is denser, it will sink.
WHAT IS THE DENSITY FORMULA?
D= M/V D= DENSITY M= MASS V= VOLUME
