Hydrogen Orbitals

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Hydrogen Orbitals
What is an orbital? It is a wave function of
an electron
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What is an orbital? Describes the coordinates
where an electron may reside in an atom The
radius of a sphere in which there is a 90 chance
of finding the electron
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The wave model of the atom

• The Bohr model of hydrogen showed the electron
  moving in certain circular orbits. This idea
  didnt work for other atoms.
• The wave mechanical model of the atom works
  equally well for all atoms.
• Electron states are described by orbitals, but
  these orbitals are nothing like orbits.

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Energy levels describe where the electrons might
be.

• n the principle energy level. Describes the
  size and energy level of an orbital. It is an
  integer greater than zero
• Orbitals for which n 2 are larger than those
  for which n 1.

n 1
n 2
n 3
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• Starting with principal energy level n 2, there
  are sublevels
• The sublevels for n 2 are 2s and 2p orbitals.

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Another view of p orbitals. Each orbital is
oriented around an axis (x, y and z)
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If hydrogen has only one electron why does it
have so many orbitals?
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• Orbital Labels
• The number (ex n 1) tells the principal energy
  level
• The letter (ex 1s) indicates the shapes
• s ? has a spherical orbital
• p ? has a two-lobed orbital
• There are four letters s, p, d, f
• d ? has five shapes
• f ? has seven shapes

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The sublevels for principal energy level n 3
are 3s, 3p and 3d orbitals.
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• Orbital Sublevels
• n 1 ? 1s
• n 2 ? 1s, 2s, 2px, 2py, 2pz
• n 3 ? 1s, 2s, 2px, 2py, 2pz, 3dyz,
• 3dxz, 3dxy, 3dx2-y2, 3dz2

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An atom has as many electrons as it has protons
to give it a zero overall charge. To be able to
arrange electrons in an atoms orbitals we need to
talk about spin. Electrons appear to be spinning
like tops. The spin can be represented by
arrows.
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Each orbital of an atom can hold two
electrons. To do this, each electron must spin
in the opposite direction
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The most attractive orbital to an electron is the
one closest to the nucleus. This is the 1s
orbital and it brings the electrons closest to
the protons of the nucleus. In its ground state,
hydrogen has one electron in the 1s orbital
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The orbitals fill in the following order 1s ? 2s
? 2p ? 3s ? 3p
The electron configuration for hydrogen is 1s1
This means there is one electron in the 1s
orbital.
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Helium has two protons and two electrons
The electron configuration for helium is 1s2
For there to be two electron in the 1s orbital,
they must spin in different directions.
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Helium with its two electrons in the 1s orbital
1s2
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Beryllium with its four electrons fill the 1s
orbital and the 2s orbital
1s22s2
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Neon with its ten electrons fill the 1s orbital,
the 2s orbital and the 2p orbital
1s22s22p6
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The last 6 electrons fill the 2p orbital in this
order
1s22s22p6
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We can represent electron configurations two
ways
Written Ne 1s22s22p6
Box diagram 1s2 2s2 2p6 Ne
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Order of filling orbitals
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For the first 18 elements of the periodic table,
write the electron configuration and fill out box
diagrams for each. Example Li
1s22s1 1s2 2s1 Li
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