Particles, bonding and structure Flashcards
What factors effect the rate of diffusion?
Temperature
Concentration gradient
Molecular mass
What is chromatography?
A method used to separate pigments(coloured substances) using filter paper and a solvent.
How do you calculate Rf value?
Distance travelled by dye/distance travelled by solvent
What is a radioactive isotope?
An isotope with an unstable nucleus which emits various types of radiation (hydrogen 3).
Medical use of isotopes
Cancer treatment (radiotherapy)
Industrial use of isotopes
Checking for leaks in gas and oil pipelines
How can you test for metals?
Electrical conductivity, malleability, ductility
Properties of ionic compounds
- high melting points
- hard but brittle
- uniform repeated structure
- unreactive when solid
- dissolves in water to create a solution
- conducts electricity only when in a solution or when molten.
Properties of covalent compounds
- Low melting points
- small finite structures
- can be very reactive due to size and combination of non metals.
- soft and brittle when solid (usually)
Properties of giant covalent structures
- very high melting points
- very hard but brittle
- uniform, covalently bonded structure
- unreactive when solid because of many strong bonds holding atoms in place.
- does’nt conduct electricity (except graphite and silicon)
- Doesn’t dissolve in water
Properties of diamond (C)
High melting points- many covalent bonds must be broken to separate atoms.
Very strong- each carbon atom is joined to 4 others in rigid structure.
Non-conductor of electricity- no free electrons; all used for bonding
Properties of graphite (C)
High melting points- many covalent bonds must be broken to separate atoms
Soft- each carbon atom joined to three others in layers. Layers held together by weak forces.
Conductor of electricity- only three carbon atoms are used for bonding; the fourth moves freely between layers
Properties of metallically bonded structures
High melting and boiling points- strong metallic bonds in all directions. Strong under compression and tension
Malleable and ductile- hammered and drawn out; layers slide without changing bonding.
Electrical and thermal conductors- close packed ions pass energy efficiently and mobile electrons carry charge
Properties of silicon dioxide
Each silicon atom joined to four oxygen atoms
Forms hard, colourless Chrystals.
High melting points- a lot of energy needed to break strong covalent bonds.
Doesn’t conduct electricity- no delocalised electrons
