Chem Flashcards
What is an element
When all of the atoms are the same
Compounds contain…..
Two or more different elements chemically combined
How do you separate a compound back into its element how do you do this
Chemical reaction
What is a mixture
A mixture is a substance made of different elements or compounds but not chemically combined
How do you separate mixtures
Filtration
Distillation
Crystallisation
What is a molecule
A molecule has any element chemically combined
What does the chemical formula tell us for the compound
A chemical formula tells us the elements in a molecule and number of atoms
When you have CaSO4 how many atoms do you have
Ca is (Calcium) and it has no small number next to it so it has (one atom)
Again the same with S(sulphur)
But with oxygen (O) it has a small 4 next to it so it has (4 atoms)
Mg(OH)2
We have 3 elements
Mg( has one atom )
O ( has 2 oxygen because you x it by the number on the outside)
H ( hydrogen has 2 atoms too)
What can physical separating techniques only be used to separate
Mixtures
What is filtration used for
Used to separate an insoluble solid from a liquid
What do state symbols tell us
They tell us the physical state of a chemical
How do we filter an insoluble substance from a liquid
Conical flask
Filter funnel
Filter paper
What is crystallisation used for
To separate a soluble solid from a liquid
What is a solution in water called
Aqueous solution
When would we use simple distillation
When you would want to separate a dissolved solid from a liquid but want to keep the liquid
What are the two stages of simple distillation
1.) You evaporate liquid by heating the liquid by heating
2.) next condense the back to a liquid by cooling
How can fractional distillation be used to separate mixtures
Fractional distillation is used to separate components that have different boiling points from a mixture
If an element has different isotopes what does this mean
Each isotope of an element has the same number of protons and a different number of neutrons
What happens to a metal atom and non metal atom when an ionic bond forms between them
The metal atom loses electrons to become positively charged ions
What properties of metals make them all useful structural materials
Metals contain metallic bonds which are very strong.Mostly have high melting and boiling points
Explain why most polymers are solids at room temperature
Because they are held together by strong covalent bonds
Explain why electrolysis is an expensive way of extracting metals from their ores
Electrolysis requires a lot of heat and electrical energy
What is carbon footprint
The amount of carbons dioxide produced by the full cycle of a product
What is the purpose of a life cycle assessment
Provides a way of comparing different products to see which cause least damage to the environment
