CHEM 問題..入嚟睇吓la!!

1.
in reactions involving transfer of electrons, i.e. redox reactions.
but strictly speaking, when sufficient energy is supplied, atoms can lose electrons to form ions. energy supplied can be in form of heat, bombardment of other atoms / ions / fast-moving electrons, photons, or simply energy released in reactions.

2.
alkane. it's compound containing carbon and hydrogen only ---- with single covalent bonds only. no double bond or triple bond, but can have ring structure.
they're unreactive to common chemicals, but can burn in oxygen. LPG contains propane and butane.
all alkanes has -ane as suffix. the prefix indicates no. of carbon in main chain.
meth- one C
eth- two C
prop- 3
but- 4
pent- 5
hex- 6
hept- 7
oct- 8
non- 9
dec- 10
undec- 11
dodec- 12
icos- 20
......
also, they can be rings. cyclohexane is alkane with six carbon, forming a ring (hexagon).
on alkanes, there can be branches, substituting various groups on it.


3.
an element can has more than one way to arrange its atoms.
when phosphorus exists as P4, it's a trigonal pyramid 三角錐體, with one P-atom on each vertex. it's yellow (white) phosphorus, which is unstable and can ignite spontaneously in air.
on the other hand, phosphorus can from a network, connecting a lot of P-atoms in one net. it's red phosphorus, more stable and can exist in air without spontaneous ignition.

elements in different forms are called allotropes. other elements also have allotropes. for example, dioxygen and ozone are two allotropes of oxygen; graphite, diamond, fullerene are allotropes of carbon; iron has three allotropes -- alpha, beta and gamma, with different arrangement of packing of atoms.

1) Na 係1隻metal ,同oxygen react mix 埋會變nao(sodium oxide,係na+ion同o2- ion既mixed)
E.G. 2Na + o2 --> 2NAO (na+/ o2-)

2)呢d都係alkanes, which are series of hydrocarbons with a carbon single bond. meth-ane 係1粒carbon, eth係2粒, hept 係7粒 ..吾同字首有吾同no. of carbon.