Earth Science Chemistry Review II

1.  Determine the name and symbol based on the atomic number for each of the elements listed below:

Atomic number 3: ____________________

Atomic number 19: ____________________

Atomic number 38: ____________________

Atomic number 90: ____________________

2.  An atom has 6 protons, 7 neutrons and 6 electrons. Fill in the blanks below for this atom:

Atomic number: _____ Atomic mass: _____ Charge: _____

Name of the element: _______________________

3.  Use the periodic table of the elements to determine how may shells or orbitals will be found in each of the following atoms when they are electrically neutral:

Neon (Ne): _____ Copper (Cu): _____ Uranium (U): _____ Lithium (Li): _____

4.  A calcium (Ca) ion has a valence (net electrical charge) of +2. How many protons and electrons does it have?

Protons: _____ Electrons: _____

5.  Sulfur is an element which can have several different valence states depending upon the local chemical environment. It may remain neutral (valence = 0), take on a positive valence or a negative valence.

If no oxygen is present, sulfur will remain neutral or take on a negative valence. When the valence becomes negative, sulfur will form the sulfide ion and fill its outer electron shell with electrons. Use the periodic table of the elements to determine what valence (or charge) the sulfide ion will have:

Valence of sufide ion: _____

If oxygen is present it will combine with the sulfur to form sulfate ions. In sulfate ions the sulfur will take on a positive valence by loosing all of the electrons in the outer shell. What valence will sulfur have in the sulfate ion?

Valence of sulfur in the sulfate ion: _____

The sulfate ion consists of four oxygens combined with one sulfur. In the space below write the formula for this complex ion:

Formula for the sulfate ion:

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