M2 - Chapter 5 Flashcards
Define orbital
an orbital is an area of space about the nucleus that can hold a maximum of two electrons with opposite spins
Define shell
a number of orbitals with the same principal quantum number(n)
Define subshell
all the orbitals of the same type within one shell
What is electron configuration
arrangement of electrons in an atom
How are electrons arranged around the nucleus
in principal energy levels or principal quantum shells
The lower the principal quantum number,
the closer the shell is to the nucleus
The first shell is
n=1
Closest to the nucleus
The higher the principle quantum number…
the greater the energy of the shell + further away from the nucleus
How many electrons can n=1 hold
2
How many electrons can n=2 hold
Up to 8
How many electrons can n=3 hold
Up to 18
How many electrons can n=4 hold
Up to 32
The principle quantum shells are split into…
Sub shells
Names of the sub shells
S p and d
Which elements have an f shell
Those with more then 57 electrons
How does the energy increase in sub shells
o The energy of the electrons in the subshells increases in the order s < p < d
What does it mean when it says the energy of the shells can overlap
4s has lower energy than 3d
What do subshells contain
One or more orbitals
Where can electrons be found
In the orbital not between them
How many electrons can each orbital contain
Max 2
How many orbitals in s subshell
one orbital (1 x 2 = total of 2 electrons)
How many orbitals in p subshell
three orbitals ( 3 x 2 = total of 6 electrons)
How many orbitals in d subshell
five orbitals (5 x 2 = total of 10 electrons)
How many orbitals in f subshell
seven orbitals (7 x 2 = total of 14 electrons)
Shape of s orbitals
Spherical
Does the size increase in the s orbitals
Yes - • The size/radius of the s orbitals increases with increasing shell number
o E.g. the s orbital of the third quantum shell (n = 3) is bigger than the s orbital of the first quantum shell (n = 1)
Shape of p orbitals
dumbbell shape
Does every shell have a p orbital
Yes - BUT NOT THE FIRST ONE n=1
How many p orbitals in each shell
Three
P orbitals occupy..
the x, y and z axes and point at right angles to each other, so are oriented perpendicular to one another
Does the size of P orbitals increase
Yes…• The lobes of the p orbitals become larger and longer with increasing shell number
Do all shells contain d orbitals
all from n=3
How many d orbitals do they contain
5
What is spin - pair repulsion
• Electrons with the same spin repel each other
How to fill orbitals
electrons will occupy separate orbitals in the same subshell first to minimise this repulsion and have their spin in the same direction
o They will then pair up, with a second electron being added to the first p orbital, with its spin in the opposite direction
What is Hunds rule
electrons will occupy separate orbitals in the same subshell first to minimise this repulsion and have their spin in the same direction
o They will then pair up, with a second electron being added to the first p orbital, with its spin in the opposite direction
Example of Hunds rule
there are three electrons in a p subshell, one electron will go into each px, py and pz orbital
Box notation for titanium
What’s special a lot 4s
• The transition metals fill the 4s subshell before the 3d subshell, but they also lose electrons from the 4s first rather than from the 3d subshell
Different blocks on the periodic table
Exceptions to periodic table
Chromium and copper
Electronic configuration of chromium
o Cr is [Ar] 3d5 4s1 not [Ar] 3d4 4s2
Electron configuration of Cu
o Cu is [Ar] 3d10 4s1 not [Ar] 3d9 4s2
Why are copper and chromium like this
because the [Ar] 3d5 4s1 and [Ar] 3d10 4s1 configurations are energetically favourable
• By promoting an electron from 4s to 3d, these atoms achieve a half full or full d-subshell, respectively
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