Properties of Substances Flashcards
What are states of matter?
Substances exist in either solid, liquid or gaseous form. These forms are known as the states (or phases) of matter.
What are the properties of liquids?
Liquids: • have fixed size and volume • are able to flow • take the shape of the bottom of the container they are in • are incompressible (not able to be compressed).
Particle Behaviour - packed closely together but they are far more loosely bonded (joined) to their neighbours but can move over one another
What are the properties of gases?
Gases:
• are often colourless and invisible (you may be able to detect their smell)
• will spread out to take the shape of the container
• have no fixed shape or volume
• can be compressed (pushed in to make them take up a smaller amount of space).
Particle Behaviour -
Gases have nothing holding their particles together. This lack of bonds allows the gas particles to travel randomly in straight lines until they hit something.
What are the properties of solids?
Solids:
• have a fixed shape • have fixed size and volume • cannot be compressed (pushed in to make it smaller) • will usually sink when placed in liquids of the same material.
Particle Behaviour - vibrate on the spot and packed in fixed positions
What are chemical properties?
Chemical properties describe how a substance reacts with other substances. A
Name some chemical properties
- burns or explodes in oxygen (this is known as combustion)
- rusts or corrodes (known as corrosion) or is corrosion-resistant
- is an acid like vinegar or a base like bicarbonate of soda or neither (this is measured by its pH)
- reacts quickly or slowly with other chemicals (this is known as the rate of reaction).
Define biodegradable
Biodegradable
Substances are classified as being biodegradable if bacteria or fungi break them down.
Define non-biodegradable
Non-biodegradable substances eventually break down but often take hundreds of years to do so. Non-biodegradable substances have structures that bacteria and fungi cannot pull apart.
What are examples of physical properties (ie what you can see).
whether it’s a solid, liquid or gas at room temperature (normally taken as 25°C)
• the temperatures at which the substance freezes or boils (known as its freezing point and boiling point)
• its appearance (such as its colour and texture, the shape of any crystals within it and whether it is shiny or dull)
• its density (how heavy it is compared to other substances of the same size)
• how hard or brittle the substance is (whether it is easily scratched or whether it crumbles)
• whether the substance dissolves in different liquids (known as solubility)
• its ability to let heat or electricity pass through it (known as its thermal and electrical conductivity).
Why is a particle model useful?
Each of the states of matter has its own characteristic properties that can be explained using a simple model called the particle model.
What is an ‘analogy’?
An analogy uses a common, everyday thing to help us understand how something that is complicated works.
eg comparing a brain to a computer
What is a particle model?
In the particle model, all substances are thought to be made of incredibly small, hard, spherical balls called particles. Each ball has energy and moves according to how much energy it has. If a particle has lots of energy, then it will move about a lot. If the particle has very little energy, then it will be sluggish and move about slowly.
What happens when you add energy or heat to particles?
They move quickly, speed up to maximum boiling point
What happens when you decrease energy or cold to particles?
They slow down, particles move less and eventually stop (freezing point (−273°C))
What happens when particles are closer to one another
There is more attraction
