SCIENCE CHEMISTRY (Sec3): Chpt5_Physical properties of ionic substances, simple covalent & giant covalent substances Flashcards
physical properties of ionic substances [5 pts]
- high m.p.s and b.p.s
- excellent conductor of electricity in molten or aqueous state
- insulator of electricity in solid state
- solubility
- hard but brittle
high m.p.s and b.p.s (ionic substances) [2pts]
- electrostatic forces of attraction: very strong
- require more energy to overcome it
excellent conductor of electricity in molten or aqueous state (ionic substances) [3pts]
- ions can move about in molten (liquid state) and aqueous state
- giant ionic lattice structure has broken down
- electricity is conducted when ions move around freely
insulator of electricity in solid state (ionic substances) [2pts]
- ions cannot move around
- held strongly at fixed positions by ionic bonds in giant lattice structure
solubility (ionic substances) [2pts]
- most ionic compounds soluble in water to form aqueous state
- insoluble in organic solvents
hard but brittle (hard - ionic substances) [2pts]
- electrostatic forces of attraction bwt. oppositely charged ions hold them strongly together
- ionic compounds can resist deforming: ions cannot move easily
hard but brittle (brittle - ionic substances) [3pts]
- strong force applied on ionic compounds: cause ions to shift away from their lattice positions
- ions of same charge approach each other: repel one another
- repulsive forces become greater than attractive forces: lattice structure broken down
physical properties of covalent substances (covalent bonding) [3pts]
- low m.p. and low b.p.
- cannot conduct electricity at any state generally
- solubility
cannot conduct electricity at any state generally (covalent substances) [2pts]
- most simple covalent molecules neutral molecules: do not have ions or delocalised electrons
- certain covalent molecules can dissociate in water to produce mobile ions to conduct electricity (e.g. hydrochloric acid)
low m.p. and b.p. (covalent substances) [4pts]
- intermolecular force bwt. molecules is very weak: less energy required to overcome it
- some simple covalent molecules evaporate easily: volatile (exist as liquids or gases at room temp.)
- m.p. and b.p. increases when molecules get larger
- intermolecular forces of attraction become stronger: more energy needed to overcome them
solubility (covalent substances) [1pt]
most simple covalent molecules are soluble in organic solvents but not in water
properties of diamond (giant covalent substances) [4pts]
- extremely high m.p.s and b.p.s
- cannot conduct electricity
- very hard
- solubility
extremely high m.p.s and b.p.s (properties of diamond) [1pt]
network of strong covalent bonds: large amount of energy is required to break these strong bonds
cannot conduct electricity (properties of diamond) [1pt]
does not have delocalised electrons or mobile ions to conduct electricity
very hard (properties of diamond) [1pt]
contains many strong covalent bonds only that requires a large amount of energy to break structure apart
solubility (properties of diamond) [1pt]
most giant covalent substances cannot dissolve in water & in organic solvents
graphite [1pt]
made of layers of planes which consist of carbon atoms joining together in a form of hexagonal rings
properties of graphite (giant covalent structure) [4pts]
- high m.p. and b.p.
- can conduct electricity
- solubility
- soft and slippery
high m.p. and b.p. (properties of graphite) [1pt]
network of strong covalent bonds: large amount of energy required to break these strong bonds
can conduct electricity (properties of graphite) [3pts]
- each carbon atom covalently bonded to three other carbon atoms only
- one electron from each atom which is not bonded: delocalised electron
- delocalised electron able to move around freely
solubility (properties of graphite) [1pt]
most giant covalent substances cannot dissolve in water & in organic solvents
soft and slippery (properties of graphite) [2pts]
- each layer held by weak intermolecular force of attraction that can be overcomed easily by small amount of energy
- layers able to slide over one another easily: soft and slippery
macromolecules [4pts]
- covalent substances
- polymers: made by joining many covalent molecules into chains of much larger molecules
- natural polymers (e.g. silk, wool, starch, rubber)
- man-made polymers (e.g. nylon, polystyrene, polyester)
properties of macromolecules [3pts]
- low m.p. and b.p.
- cannot conduct electricity in any state
- solubility
