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MolE01 The smallest particles as building units of elementsWhite, read, black und green
balls as models for H, C, O and Cl atoms are available in expensive kids
for molecule modelling.
Photo 1: White,
read, black und green plastic beads of different sizes
were introduced into teacher training 20 years ago by El-Marsafy.
A tiny piece of chewed chewing gum (alternatives: welding
or wire) is enough to connect two white, red,
green, blue beads as molecule models of the elements
hydrogen, oxygen, chlorine or nitrogen.
Photo 2
- 5: By introducing pieces of nails of suitable sizes into the holes
of a red and two black beads their masses are enlarged to use them for a
visualisation of atomic masses: The models of 16, 12, 14 H atoms balance
the masses of the model of O, C and its isotope C-14. Carbon isotope
12C
is used to express atomic
and molecular masses . The "unified atomic mass unit (u), or Dalton
(Da)" is defined to be one twelfth of the mass of a 12C atom 12C
1. Each element has
its own type of atoms.
2. Above each element
symbol you can see how much an atom (of the most frequent isotope) weighs:
H: 1,0 unit,
He: 4,0 units, C: 12,0 units, N: 14 units, O: 16,0 units, .............
(1
mole H, He, C, N, O atoms weigh 1, 4,
12, 14, 16 g)
3. Under each element
symbol you can see how many electrons
(negative
charge) and how many protons (positive charge)
this atom
has.
Atoms usually are the smallest particles
in noble gases: He, Ne, Ar, Kr, Xe.
Molecules are the
building units of nonmetallic elements like S8
= sulfur (H2, O2, N2, Cl2).
Metallic elements
like magnesium (i.e. I, II, III) are made of bonded groups of atoms called
crystal lattices.
back....... go on........firfirst published:
25.10.2001..................last modification: 21.03.2007