4-4 A New Approach to the Atom

Review Energy is quantized ( found in specific amounts) Electrons have wavelike behavior Impossible to know electron position and momentum. Can predict the probability of electron location Called the Quantum-mechanical model

Probability and Orbital An orbital is the region where a given electron is likely found. The density of an electron cloud is called the electron density. Higher density – more likely to find electron Lower density – less likely to find electron

Each orbital has specific sizes and shapes. s, p, d, and f.  The shape of the cloud is where electrons are likely to be found 90% of the time.

S orbital

P orbital- see figure 4-26 in book

d orbital – see figure 4-27 in book

Orbitals and Energy The energy levels are given the initial n, called the principle quantum number As the energy of an electron increases so does its principle quantum number n =1 has only one sublevel n = 2 has 2 sublevels, 2s and 2p n = 3 has three sublevels, 3s, 3p, and 3d 4 sublevels, 4s, 4p, 4d, and 4f

Note 3d fills before 4p, this is what is found in nature * Note 3d fills before 4p, this is what is found in nature. The energy levels get closer together.

Each of the sublevels orbits can contain up to two electrons that travel in opposite directions or spins

Electron Spin The spin of an electron is either clockwise or counter clockwise These spins create magnetic fields

Summary of Energy Levels, Sublevels, and Orbitals Principal Energy Level Sublevels Orbitals n = 1 1s 1s (one) n = 2 2s, 2p 2s (one) + 2p (three) n = 3 3s, 3p, 3d 3s(one) + 3p(three)+3d(five) n = 4 4s, 4p, 4d, 4f 4s(one)+4p(three)+4d(five)+4f(seven)