Quantum Mechanic Theory and the Atom Structure

de Broglie (1924) - electrons also wave-like.

Electrons can only move at certain wavelengths around the nucleus – helps explains why energy absorbed in specific quantized values.

Problems - Bohr model is 1-D model. - e- also have wave-particle duality.

Heisenberg (1927) - it is impossible to know precisely the velocity and position of a particle at the same time – Heisenberg Uncertainty Principle

Schrödinger (1926) – developed a wave equation that describes the energies and behaviour of subatomic particles.

Determines the probability of finding an electron in a 3-D volume of space around the nucleus.

Each energy level's boundary is the area of electron location

90% of the time.

Bohr’s orbits called principal energy levels, or quantum numbers (n).

The principal quantum number (n) indirectly describes the size and energy of an orbit.

• Each principle energy level has a set of sublevels of probable electron location.

• Sublevels are described in terms size, shape and orientation in space.

• There are four types that appear in this order:

s p d f

• Sublevels contain multiple orientations in space.

n = 1

n = 2

n = 3

• # of sublevels per energy level (n) equals the principal quantum number for the level.

n = 1 – contains one sublevel: 1s n = 3 – contains three sublevels: 3s, 3p, and 3d.

s p d

s sublevel (sphere) – 1 orbital orientation present.

p sublevel (dumbell) – 3 orbital orientations.

d sublevel (cloverleaf) – 5 orbital orientations.

f sublevel (indeterminate) – 7 orbital orientations.

1s 2s 2p 3s 3p 3d

n = 1

n = 2n = 3

Energy Level

Sublevels Total Orbitals

1 s 1s

2 s,p 1s+3p = 4

3 s,p,d 1s+3p+5d = 9

4 s,p,d,f 1s+3p+5d+7f = 16

n n types n2