Elements and Compounds

1
Elements and Compounds(??????)

• Relative (??) abundance (??) of different
  elements
• Differences between compound (???) and mixture
  (???)

2
Some definitions (??)

• Element (??) e.g. hydrogen, oxygen A pure
  substance containing one kind of atoms only.
• Compound (???) e.g. water, sodium chlorideA pure
  substance in which more than one kinds of atoms
  are chemically combined together.
• Mixture (???) e.g. sea water An impure substance
  with more than one element or compound mixed
  together.

3
Relative abundance (??) of different elements on
the earths crust (??)
4
? List the 4 most abundant (???) elements on the
earths crust in order of decreasing abundance
(??).
5
? List the 4 most abundant (???) elements on the
earths crust in order of decreasing abundance
(??).

• Oxygen, Silicon, Aluminium, Iron

6
Relative abundance of different elements in the
universe
7
? Which are the most plentiful (???) substances
containing silicon and oxygen respectively on the
earths crust ?
8
? Which are the most plentiful (???) substances
containing silicon and oxygen respectively on the
earths crust ?

• Common nameRock, sand, quartz
• Chemical nameSilicon(IV) oxide, silicon dioxide
• FormulaSiO2(s)

9
Difference between Compound and Mixture of
elements
10
Differences between iron(II) sulphide and
iron/sulphur mixture
11
Differences between iron(II) sulphide and
iron/sulphur mixture
12
Differences between iron(II) sulphide and
iron/sulphur mixture
13
Structural (????) difference between mixture and
compound
14
Differences between carbon dioxide and
oxygen/carbon mixture
15
Differences between carbon dioxide and
oxygen/carbon mixture
16
Differences between carbon dioxide and
oxygen/carbon mixture
17
Structural (????) difference between mixture and
compound
mixture of carbon and oxygen
compound ofcarbon dioxide
18
Differences between compound and mixture
19
? What is the formula of water ? What is the
formula of sea water ?
20
? What is the formula of water ? What is the
formula of sea water ?

• Water - H2O
• Sea water - no formula, only pure substances can
  have formulas

21
? Which of the followings is most plentiful in
the nature, pure elements, compounds or mixtures ?
22
? Which of the followings is most plentiful in
the nature, pure elements, compounds or mixtures ?

• MixturesExamplesair mixture of elements and
  compounds sea water mixture of
  compoundsrocks mixture of elements and
  compounds