Chapter Menu
Section 7.1
Present-Day Atomic Theory
Section 7.2
The Periodic Table and
Atomic Structure
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Present-Day Atomic Theory
• Relate emission spectra to the electron
configurations of atoms.
• Relate energy sublevels and orbitals within
the atom.
Present-Day Atomic Theory
electromagnetic spectrum: the entire range of
electromagnetic radiation
Present-Day Atomic Theory
sublevel
aufbau principle
Heisenberg uncertainty principle
orbital
electron configuration
Electrons are organized in energy
levels and sublevels.
Expanding the Model
of the Atom
• Danish physicist Niels Bohr suggested that
electrons revolve around the nucleus like
planets revolve around the Sun.
Expanding the Model
of the Atom (cont.)
• Bohr’s model explained
hydrogen’s emission spectrum,
but failed to explain any other
element’s emission spectrum.
• The current atomic model
explains electron behavior by
interpreting the emission
spectra of all the elements.
Expanding the Model
of the Atom (cont.)
• The periodic table reflects each element’s
electron arrangement.
Expanding the Model
of the Atom (cont.)
• To calculate the exact amount of energy
released by the electrons in atoms:
– the higher the frequency of a wave and the
shorter wavelength, the greater the energy
of the radiation
– the lower the frequency and the longer the
wavelength, the lower the energy released
Expanding the Model
of the Atom (cont.)
Expanding the Model
of the Atom (cont.)
• By absorbing a specific amount of energy,
an electron can jump to a higher energy
level.
• When the electron falls back to the lower
energy level, it releases the same amount of
energy in the form of radiation with a definite
frequency.
Expanding the Model
of the Atom (cont.)
Expanding the Model
of the Atom (cont.)
• Energy levels within an atom are
characteristic of each element.
Expanding the Model
of the Atom (cont.)
• Closely spaced lines in a spectrum suggest
that sublevels—divisions within a level—
exist within an energy level.
– The energy sublevels are indicated
as s, p, d, or f.
Expanding the Model
of the Atom (cont.)
• The aufbau principle states that each
electron occupies the lowest energy
sublevel available.
Electrons Distribution
in Energy Levels
• Each energy level has a specific number of
sublevels, which is the same number of the
energy level.
Electrons Distribution
in Energy Levels (cont.)
Electrons Distribution
in Energy Levels (cont.)
• The Heisenburg uncertainty principle
states that it is fundamentally impossible to
know precisely both the velocity and
position of a particle at the same time.
Electrons Distribution
in Energy Levels (cont.)
• The only quantity that can be known is the
probability for an electron to occupy a
certain region around the nucleus.
Electrons Distribution
in Energy Levels (cont.)
• The space in which there is a high
probability of finding an electron is called
an orbital.
• Each energy level relates to orbitals of
different sizes and shapes.
Electrons Distribution
in Energy Levels (cont.)
Electrons Distribution
in Energy Levels (cont.)
• The most stable arrangement of electrons
in sublevels and orbitals is called an
electron configuration.
• Because orbitals are mostly
empty space, this space
can be used by another pair
of electrons and the orbitals
can overlap.
Section Assessment
Atoms move in circular orbits in which
atomic model?
A. quantum mechanical model
B. Rutherford’s model
C. Bohr’s model
D. de Broglie’s model
Section Assessment
Electron behavior is explained by
interpreting ___.
A. emission spectra
B. the number of energy levels
C. how quickly the electrons revolve around
the nucleus
D. the number of covalent bonds
The Periodic Table and Atomic Structure
• Distinguish the s, p, d, and f blocks on the
periodic table and relate them to an element’s
electron configuration.
• Predict the electron configurations of elements
using the periodic table.
The Periodic Table and Atomic Structure
orbital: space in which there is a high
probability of finding an electron
The Periodic Table and Atomic Structure
inner transition element
A predictable pattern can be used to
determine electron arrangement in
an atom.
Patterns of Atomic Structure
• The shape of the modern periodic table is a
direct result of the order in which electrons
fill energy sublevels and their orbitals.
Building Electron Configurations
• Chemical properties repeat when elements
are arranged by atomic number because
electron configurations repeat in a certain
pattern.
Building Electron Configurations (cont.)
Building Electron Configurations (cont.)
• Noble gas notation uses symbols in
brackets to shorten inner electron
configurations of other elements.
• The stable electron configurations explain the
lack of reactivity of the noble gases.
Building Electron Configurations (cont.)
Building Electron Configurations (cont.)
• Experimental evidence indicates that the
4s and 3d sublevels are close in energy,
with the 4s sublevel having a slightly lower
energy.
Building Electron Configurations (cont.)
• The transition elements are any of the
elements in group 3 through 12 of the
periodic table, all of which are metals.
– They lose electrons to attain a more stable
configuration.
– Most have multiple oxidation numbers
because their s and d orbitals are so close
in energy that electrons can be lost from
both orbitals.
Building Electron Configurations (cont.)
• The lanthanides and actinides are called
the inner transition elements because
their last electron occupies a 5f orbital in
the seventh period.
The Size of the Orbitals
• The higher the energy, the farther the
outermost electrons are from the nucleus.
• As the valence electron gets farther from the
nucleus, the s orbital it occupies gets larger
and larger.
Section Assessment
As the valence electron gets farther from
the nucleus, its s orbital becomes:
A. positively charged
B. negatively charged
C. larger
D. smaller
Section Assessment
The most common oxidation number for
the inner transition elements is:
A. 1+
B. 2+
C. 3+
D. 4+