Atomic and Lewis Model Practice
An atomic model and a Lewis model are two ways of
representing an atom. An Atomic or Bohr model shows the
atom’s nucleus and electron orbits. A Lewis model only shows
an atom’s valence electrons.
45
To make an atomic model of Scandium
21
SC
1. Draw a circle to represent the atom’s nucleus
2. From the periodic table fill in the atom’s
number of protons and neutrons
21 p+
24 n
3. Around the nucleus, draw the number of
electron orbitals according to Scandium’s
period - 4.
3e8e8e-
4. Add the number of valence electrons to the
outer shell according to Scandium’s group
21 p+
24 n
5. Since the valence shell has 2e-, then every
other shell must be filled. Backfill the other
shells; 8e- in the third, 8e- in the second, 2e- and in the first.
Label each orbit with the total; do not draw a bunch of little e6. Check your math: 2+8+8+3 = 21 electrons. You’re done!
2e-
For a Lewis model, Gilbert Lewis was only Lewis was only
concerned with valence electrons.
1. In large letters, write the element’s symbol
Sc
2. Lewis used dots to indicate valence electrons. Determine the
number of Scandium’s valence electrons according to its
group – 3. Starting at 3:00, draw a dot slightly higher than
center.
Sc
3. Add further electrons, one at a time, at 6, 9, and 12:00. If an
element has more than 4 valence electrons, start again at
3:00, finishing with up to 8 back at 12:00 and aligning the
electrons as shown below. Remember, a Lewis model is
limited to the maximum number of valence electrons - 8
4.
4 8
3
7
1
5
2 6
5.
and done!
Sc