Atomic orbitals and electronic configurations Flashcards
………… first put forward the quantum theory
Max Planck
Max Planck was the first to put forward the……………
quantum theory
the quantum theory is
used to describe the arrangement of electrons around the nuclei of atoms
according to the quantum theory,
electrons can only exist in certain well-defined energy levels called quantum shells
a quantum shell
defines the energy level of an electron
electrons in the first quantum shell have
the lowest energy for that element
the first quantum shell is located in
the region closest to the nucleus
each quantum shell, apart from the first, is
divided into subshells of slightly different energy levels
there is only one …….. in the first…………labelled………
subshell in the first quantum shell, labelled 1s
the second quantum shell has
two subshells labelled 2s and 2p
electrons in the 2p subshell have……..than electrons in the 2s subshell
a slightly higher energy level than the electrons in the 2s subshell
the third quantum shell is divided into
three subshells, 3s, 3p and 3d.
the fourth quantum shell is divided into
four subshells, 4s, 4p, 4d and 4f.
each subshell contains
orbitals
orbitals are
regions within atoms that can hold up to two electrons with opposite spins
the electron in a hydrogen atom is in a ……… so
an s subshell so the orbital is described as a 1s orbital
s orbitals are……. in shape
spherical
2s orbitals are…………than 1s orbitals
larger
to draw orbitals, we use………….axes
x,y and z as 3D Cartesian axes ( axes at mutual right angles)
there is a …% probability of finding the electron within the boundaries of its s orbital
90%
the 2p subshell contain
three separate p orbitals, Px, Py and Pz
the p orbitals are …………in shape
elongated dumbbell
p orbitals have variable
charge density
there is a …..% probability of finding the electron within the boundaries of its p orbital
90%
the only difference between Px, Py and Pz orbitals is
their orientation in space
Px, Py and Pz orbitals are arranged at
mutual right angles
the first quantum shell can hold
2 electrons
the second quantum shell can hold
8 electrons
the third quantum shell can hold
18 electrons
the fourth quantum shell can hold
32 electrons
generally, electrons occupy
the next orbital when the previous one is full
for all the elements after calcium,
the energy of 3d orbitals is less than that of 4s orbitals
Hund’s rule states that
electrons will occupy the orbitals singly before pairing takes place
with knowledge that for elements after calcium in the periodic table the 3d orbital has less energy than the 4s orbital, explain why the electronic configuration of scandium (next after Ca) is 3d(1) 4s(2) and not 3d(3).
the 3d orbitals are more compact than 4s ones, so electrons in the 3d orbital have a greater mutual repulsion than they would in the 4s orbital.
the Pauli Exclusion Principle states
that two electrons cannot occupy the same orbital unless they have opposite spins. Electrons spin is usually shown by the use of upward and downward arrows
