Science - year 8 - chemistry Flashcards
What are the 3 physical states of matter?
Liquids
Solids
Gases
What is a solid substance
Solids have a fixed shape and volume.
The particles in solids are packed together much closer than the particles in a gas or liquid.
What is a liquid?
Liquid is a fluid that flows.
Liquids have a fixed amount but no fixed shape.
The spaces between the particles in liquids are almost the same as in solids.
What are gases
Gas has no shape or volume.
Gases are also fluid, and can flow in any direction.
The particles of a gas spread out until they occupy all available space.
Example of a solid
Examples of solids include:
Brick Coin Iron bar Banana Rock Sand Glass (no, it does not flow) Aluminum foil Ice Wood
Example of a liquid
Examples of liquids include:
Blood Honey Wine Water Mercury (a liquid metal) Oil Milk Acetone Alcohol Coffee
Example of gases
Air Natural gas Hydrogen Carbon dioxide Water vapor Ozone Nitrogen Argon
What is solid to liquid?
Melting
What is Liquid to gas
Boiling
What is gas to liquid
condensing
What is a liquid to solid
Freezing
What is physical change?
Melting = a physical change but no changes to the chemical
For example ice changes state to liquid water than again to water vapour - gas
No new chemical
temporary
reversable
No new product made
What is a chemical change?
Burning = a chemical change
For example Magnesium burns with a bright white light to form a white powder.
This changes the chemical to magnesium oxide
new product is formed
difficult to reverse
new chemical made
permanent
Examples of chemical change
Rusting Explosion Burning wood Souring milk Digesting food Cooking an egg Heating sugar to form caramel Baking a cake Rusting of iron Burning a candle
Examples of a physical change
Melting an ice cube
Breaking a bottle
Boiling water
Shredding paper
Physical properties
Testing a substance for its physical properties doesn’t destroy the substance, or change it into anything new.
Physical property examples
State at room temperature.
o Freezing, boiling or melting point.
o Appearance (colour, texture, shiny, dull, shape)
o Density (how heavy it is compared to other substances of the same size)
o How hard or brittle (easily scratched or crumbles)
o Solubility (dissolves in different liquids)
o Conductivity of heat or electricity
Chemical properties
Chemical properties describe how a substance reacts with
other substances. A new substance is formed in the process,
often with very different properties.
Chemical property examples
Combustion (burns or explodes in oxygen)
o Corrosion (rusting)
o pH (acid or base or neither)
o Rate of reaction (speed it reacts with other chemicals)
o Flammability (how easily a substance will burn
What is a mixture?
Mixtures are substances that are formed by physically mixing two or more substances.
Mixtures can be easily separated by evaporating, dissolving or filtering
Includes:
Homogenous - Particles uniformly distributed. E.g. Salt water, cordial
Heterogeneous - Particles not uniformly distributed. E.g. Vegetable soup, chocolate chip biscuit
What is an element?
One type of atom only which can not be broken down further e.g. Copper Iron Gold Hydrogen Oxygen
What is a compound?
Two or more types of atoms, chemically joined to form a molecule. For example:
Pure water
Salt
Sugar
What are metals?
Solids at room temperature Good electrical conductors Flexible- ductile and malleable Good heat conductors Strong Shiny
What are non metals?
Good heat insulators Good electrical insulators Often gases/liquids or solids that melt easily Dull Brittle
Examples of non-metals
Oxygen
Chlorine
Glass
Examples of metals
Gold Iron Tin Copper Lead Zinc
