Structure 1.1-1.3 Flashcards
Element
Made of atoms with the same number of protons
Compound
Composed of atoms of different elements (different number of protons) and are chemically bonded together in a fixed ratio
Mixture
Composed of more than 1 element or compound in no fixed ratio, which are not chemically bonded together. Can be separated by physical methods, and have variable properties
Pure substance
Elements and compounds Cannot be separated into simpler substances by physical means. Have fixed properties
Heterogeneous mixture
A mixture without uniform composition and properties
Homogeneous mixture
A mixture with uniform composition and properties
Solute vs solvent
Solute is dissolved in solvent to form a solution of solvated ions or molecules
Hydrated ions
Ions surrounded by water
Saturated solution
A solution where no more solute can be dissolved at that temperature
Solubility
Amount of a solute needed to form a saturated solution
Miscible liquids
Liquids that form one uniform layer of homogeneous mixture
Immiscible liquids
Liquids that do not mix and form 2 separate layers
Filtration
Physical separation technique used on heterogeneous mixtures with an insoluble solid
Evaporation
Physical separation technique used for soluble solids with difference in volatility
Steps of recrystallisation
- Shake sample with solvent and warm
- Filter hot and throw away residue
- Cool slowly so crystals form
- Filter cold and keep residue
- Wash with cold solvent to get rid of any left impurities
- Dry product
Distillation
Physical separation technique used for separating 2 miscible liquids in a homogeneous mixture with a difference in boiling point.
Density of a substance
What density is and how it is calculated
Density is the mass per unit volume (g cm^-3)
Density= mass/ volume
What is the shape of a solid?
Fixed in a regular, repeating lattice structure
What is the volume of a solid?
Fixed
Are solids able to flow?
Not usually able to flow
What is the compressability of solids?
Solids are not able to compress
What is the density of solids?
Solids have higher densities than gases and most liquids, except water, where the solid form is less dense than the liquid form
What is the shape of a liquid?
Liquid’s shape changes- it is able to flow to match the shape of the object.
Variable shape
What is the volume of liquids?
Fixed
Are liquids able to flow?
Yes, they can flow easily
Are liquids able to be compressed?
No, they are not able to be compressed
What is the density of liquids?
Liquids generally have a lower density than solids, but a higher density than gases.
Except water, where it is denser as a liquid than a solid
What is the shape of gases?
They have a variable shape, which expands to fill the container
What is the volume of gases?
Variable, depending on temperature and pressure
Are gases able to flow?
They are able to diffuse easily
What is the compressibility of gases?
They are able to compress
What is the density of gases?
Gases have the lowest density, lower than solids and gases
What is melting?
