Electronic Configuration Flashcards
what is an atom?
an atom is the smallest possible unit of an element that retains the properties of that element.
the nucleus centre of an atom contains?
neutrons(neutral) and protons(positive)
mass number calculation
proton + neutron = mass number
Why do all the atoms of a given element have the same number of protons, yet may have different masses?
Given that an element is solely characterized by Z, atoms of same element can have varying N. Such subspecies of elements with same Z but different N and A are termed Isotopes.
The four quantum numbers are?
principal, azimuthal, magnetic and spin
The principal quantum number is denoted by the letter?
‘n’
n represents atomic shell
1, 2, 3, 4
The principal energy level is labelled 1-7 from k to q
K=1 L=2 M=3 N=4 O=5 P=6 Q=7
How to calculate maximum number of electrons that can occupy an energy level (n)
2n^2
azimuthal quantum number is denoted by
‘I’
How to calculate number of azimuthal values (I)
I = 0 to I = (n-1)
what will be the possible values of I for N-shell?
N shell = 4
I = 0 to I = (n - 1)
I = 0 to I = (4-1)
I = 0, 1, 2, 3.
the four sub-levels
s,p,d,f
in I quantum number
For l = 0 = S orbital
l = 1 = P orbital
l = 2 = d orbital
l = 3 = f orbital
what if n= 4 and I= 2
4d electron
An electron with n= 2 and l = 0 would be?
2s electron
magnetic quantum number is denoted by
‘m’
the maximum number of orbital spatial orientations (m) is calculated by:
(2l+1) m = l, (l-1), (l-2),…0, -1,-2,… -l. They basically have integer values of -l to 0 to l
For S orbital, remember that the value of l = 0, this implies that ml= 0. This interprets that S orbital is oval/spherical in shape hence it has no directional orientation in space.
so what is the m values of D orbital
-2, -1, 0, 1, 2
list three functions of quantum numbers
- They are used to determine the electronic configuration of atoms
- They are used to determine the location of an atoms electrons.
- They help us to understand other characteristics of atoms such as ionisation and atomic radius.
So why does the spin quantum number have values of either +1/2 or -1/2?
Remember that an electron spins around an axis & has both angular momentum and orbital angular momentum.
So because angular momentum is a vector quantity, the spin quantum number(s) has both magnitude (1/2) and direction (+ or -). Electron can spin only in 2 directions: clockwise and anticlockwise.
What are the values of electron spin
+1/2 or -1/2
For example, hydrogen has 1 electron in its K shell, so the electron assumes n = 1; hence l = 0 and m = 0; also, s = +1/2.
But for helium with 2 electrons in its “s” orbital, the first electron assumes the same quantum numbers as that of hydrogen i.e. n = 1; hence l = 0 and m = 0; also, s = +1/2. Whereas the 2nd electron assumes a different set of quantum numbers i.e. n = 1; hence l = 0 and m = 0; also, s = -1/2.
p orbital arrangment
2px 2py 2pz
Are the following two states allowed for N by the Pauli principle?
1s2 2s2 2px1 2py1 2pz1 or 1s2 2s2 2px2 2py1 2pz0
Which is more stable and why?
1s2 2s2 2px()2py()2pz() is more stable than
1s22s22px()2py()2pz()
Half-filled P orbital
Maximum number of electrons in a sub shell
2(2l + 1)
“l” being azimuthal number or s,p,d,f. s= 0, p = 1, d= 2, f= 3.
The total number of possible orbitals with the same value of l formula
2l + 1
