C2 Flashcards
Define relative atomic mass?
The mean mass of an atom compared to 1/12 the mass of a Carbon-12 atom
What is the symbol for Relative atomic mass?
Ar
Define relative formula mass
The mean mass of a unit of substance compared to 1/12 the mass of a Carbon -12 atom
What is the symbol for relative formula mass?
Mr
Define empirical formula
Shows the simplest whole number ratio of the atoms of each element in a compound
What does pure mean?
Consists of just one element or compound
How does purity affect melting point? (Two ways)
Melting point is reduced and is over a range of temperatures
What is a solute?
A substance (solid) that dissolves
What is a solvent?
The substance which does the dissolving (liquid)
What does soluble mean?
A substance can dissolve in a particular solvent
What is the filtrate?
The substance that passes through the filter paper
What is the residue in filtration?
The substance that stays on the filter paper
What does saturated mean?
No more solute can dissolve at that temperature
What does a condenser do?
Cools a gas back to a liquid state
What does fractional distillation do?
Separates two or more substances from a mixture in the liquid state - they have to have different boiling points
What is the stationary phase?
In chromatography the part that does not move - the paper or the plate
What is the mobile phase?
In chromatography the part that moves - the solvent
What is the stationary phase in gas chromatography?
Silica or alumina powder
What is the mobile phase in gas chromatography?
An unreactive carrier has such as nitrogen
How do you calculate the Rf value?
Distance travelled by substance divided by distance travelled by solvent
How would you separate a mixture of insoluble and soluble substances?
Dissolving followed by filtration
How would you obtain a solute from a solution
Crystallisation
How would you obtain a solvent from a solution
Simple distillation
How would you separate coloured soluble substances?
Paper or thin-layer chromatography
What does malleable mean?
Bend without shattering
What does ductile mean?
Can be pulled into wires
Which side of the periodic table are non metals found on?
Right
Metal oxides in solution are acidic or alkali?
Alkaline
Non metal oxides in solution are acidic or alkaline?
Acidic
What is the maximum number of electrons in each shell?
2.8.8.18
What charge do metal ions have?
Positive
What is an ion?
A charged particle formed when atoms gain or lose electrons
What is ionic bonding?
Attraction between positive and negative ions
What is a covalent bond?
A shared pair of electrons - the attraction between the shared pair of electrons the nuclei of the bonded atoms
What are intermolecular forces?
Weak forces of attraction between molecules
What are giant covalent structures?
Many non-metal atoms joined by covalent bonds arranged in a repeating regular structure
Which types of polymers have cross-linking?
Thermosetting
What is metallic bonding?
The attraction between positive metal ions in a lattice and delocalised electrons
What is the order of elements in the periodic table?
In order of increasing atomic number
What are allotropes?
Different forms of an element with different atomic arrangements, e.g. diamond and graphite
Why doesn’t diamond conduct electricity?
There are no delocalised electrons
What does graphite conduct electricity?
It has delocalised electrons, free to move
What change of state happens during condensing?
Gas to liquid
What are the typical sizes of nano particles?
1-100nm across (x10-9m)
How do you calculate surface are to volume ratio?
Surface area divided by volume
What are the risks associated with nano particles?
Can be breathed in
Pass through skin
May take a long time to break down
Toxic substances may stick to them
