91Ó°ÊÓ

What is the energy of red light with a wavelength of \(660.5 \mathrm{~nm}\) ?

Which type of electromagnetic radiation has a wavelength roughly on the order of the height of a person? What can you say about the energy of this radiation?

Draw a Bohr model for an atom of sulfur (S). How many additional electrons can fit into the \(n=3\) shell?

Why is an electron in a shell that has a low value of \(n\) in a more stable arrangement than one in a shell that has a higher value of \(n\) ?

How many electrons can the \(n=5\) shell in an atom hold?

The ground state for the lithium (Li) atom and the scaled energies of its shells are shown below. Draw a Bohr diagram for the lowest-energy excited state of lithium.

Draw a Bohr diagram for a \(\mathrm{Li}^{+}\) cation in its ground state.

An atom has atomic number 6 and has eight electrons. (a) Which element is this? (b) Is this a neutral atom, a cation, or an anion? If it is an ion, what is its charge? (c) Draw a Bohr diagram for this atom in its ground state.

Without looking at a periodic table, use electron-configuration notation to show how electrons are distributed in a ground-state atom with 33 electrons. How many valence electrons does this atom have? What periodic table group would you expect to find it in? Now look at a periodic table and determine the atom's identity.

Using a four-block periodic table as a guide, determine the ground-state electron configuration of copper (Cu). Answer: You should have arrived at \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 4 s^{2} 3 d^{9}\), because copper is nine deep into the d block of period 4 . However, copper is one of those exceptions, and its true electron configuration is \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 4 s^{1} 3 d^{10}\).