Topic 1 - Matter and Energy - Revsworld

30. Spectral lines: Determining which electron transition will produce spectral lines
Concept Task: Be able to determine which electron
transition will produce spectral lines.
RECALL that spectral lines are produced ONLY when
an electron from an excited state (High level) returns
to the ground state (Low level).
Study the notes below to help you answer
questions on electron transitions between two shells.
Electron transition from:
Low to higher shell :
Ex: 5 th shell to 6 th shell
. Energy is absorbed (gained) by the electron
. Energy of the atom increases
High to Lower shell:
Ex: 6 th shell to 5 th shell
. Energy is released (emitted) by the electron
. Produced bright line spectrum of colors
. Energy of the atom to decreases
NOTE:
The greater the difference between the two
electron shells, the more energy is absorbed
or released.
Topic 3 – The Atomic Structure
.
Example 25
As an electron moves from 3 rd electron shell to
the 4 th electron shell, the energy of the atom
1) Increases as the electron absorbs energy
2) Increases as the electron releases energy
3) Decreases as the electron absorbs energy
4) Decreases as the electron releases energy
Answer: Choice 1. The transition is from a
lower (3 rd ) to a higher (4 th ) shell.
Example 26
Electron transition between which two electron
shells will produce bright line spectrum of colors?
1) 2 nd to 3 rd 3) 1 st to 4 th
2) 3 rd to 4 th 4) 2 nd to 1 st
Answer: Choice 4 because spectrum of colors
are only produced when electron goes
from a higher (2 nd ) to a lower (1 st ) shell.
Example 27
As an electron in an atom moves between
electron shells, which transition would cause the
electron to absorb the most energy?
1) 1 st to 2 nd 3) 2 nd to 4 th
2) 2 nd to 1 st 4) 4 th to 2 nd
Answer: Choice 3. Energy is absorbed when
electron goes from low to high level.
Although choice 1 is also from low to high,
Choice 3 has a greater difference
between the two shells.
31. Excited and Ground State: Determining configuration for ground and excited state atom
Concept Task: Be able to determine which electron
configuration is of an atom in the ground
or excited state.
To determine which configuration is of an atom in the:
Ground state:
LOOK for a configuration that is the same as on the
Periodic Table for that atom:
Excited state
LOOK for a configuration that has the same total number
of electrons as of the element given, BUT, different
arrangement as on the Periodic Table
Examples:
2 – 8 – 5 is the Ground state configuration for phosphorous
2 – 7 – 6 is an Excited state configuration for phosphorous
Example 28
Which is an excited state electron
configuration for a neutral atom
with 16 protons and 18 neutrons?
1) 2-8-5-1 3) 2-8-6-2
2) 2-8-8 4) 2-8-6
Correct: Choice 1 . An atom with 16
protons is sulfur. The atom also
has 16 electrons since it is neutral.
Choice 1 has a total of 16
electrons. But the electrons are
arranged differently from the
ground state configuration
that is given on the Periodic Table
for sulfur.
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