91Ó°ÊÓ

Magnesium (Mg) reacts with chlorine \(\left(\mathrm{Cl}_{2}\right)\) to form the compound \(\mathrm{MgCl}_{2}\). (a) Predict the formulas for the compounds formed when all the other alkaline earth metals react with chlorine. (b) Predict the formulas for the compounds formed when all the alkaline earth metals react with bromine. (c) Explain what principle you used to make your predictions.

State two things that are unique about the noble gases.

How many elements are in each transition metal period of the periodic table? How many are in each lanthanide (rare earth)/actinide period?

Metals are excellent conductors of electricity. Nonmetals are poor conductors of electricity and are called insulators. Some elements have the ability to conduct electricity roughly between that of metals and nonmetals. Give some examples of these elements, and name the class they belong to.

It always takes energy to remove an electron from a neutral atom. Explain why, and name the minimum amount of energy it takes to do this.

A student claims that the way to convert a neutral atom of \(\mathrm{Cl}\) into a \(\mathrm{Cl}^{-}\) anion is to decrease its atomic number by one while leaving the number of electrons unchanged. (a) Will this give the atom a \(-1\) charge and convert it into an anion? Explain. (b) Will the atom still be an atom of the element chlorine? Explain. (c) What should the student have done?

What would the charge on a ion be if, starting from the neutral atom: (a) You add three electrons. (b) You remove four electrons. (c) You add two neutrons to the nucleus.

Two students are studying using a plastic model of the atom to which they can easily add or remove electrons, protons, and neutrons. They build a model for the neutral \({ }_{6}^{14} \mathrm{C}\) atom. Their next job is to make the \(+2\) ion of this carbon isotope. Student \(\mathrm{X}\) removes two electrons from the atom. Student \(\mathrm{Y}\) adds two protons to the atom's nucleus. Did both students successfully construct a \(+2\) carbon-14 cation? Explain.

What is the trend in first ionization energy as you go down a given group in the periodic table? As you go across a period from left to right?

Of the atoms \(\mathrm{Na}, \mathrm{Mg}\), and \(\mathrm{Al}\), which should be the most difficult to ionize? Which has the smallest first ionization energy?