Chemistry Flashcards
Elements are
Pure substances made from 1 type of atom
Compounds are
Pure substances made from 2 or more elements which are chemically joined together
Mixtures are
2 or more substances that are not chemically joined
What is an alloy
A mixture of 2 or more elements, one of which is always a metal
What are 4 signs of a chemical change
Colour change, energy change (heat, light or sound), gas (bubbles), precipitation (cloudy solid appears in a solution)
What chemical change always happens
Forms new substances
Chemical changes are usually ? to reverse
Very difficult or impossible
What is a physical change
When the appearance or form changes but no new substances are made
What is sodium chloride
Sodium+chlorine
What is the most reactive metal
Potassium
What is the least reactive metal
Platinum
What is combustion
Burning
How can you remember the first 5 most reactive metals
End in -ium
How can you remember the 4 least reactive metals
Used in jewelry
Most reactive metals are ? to extract from their compounds
Very hard
Least reactive metals are ? to extract from their compounds
Easy
How can the metals in the middle of the reactivity scale be extracted from compounds
They can be extracted by being roasted with another chemical such as hydrogen or carbon
Hydrochloric acid is
Chloride
Sulfuric acid is
Sulfate
Nitric acid is
Nitrate
