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Part 2: Complete the worksheet below.

Each element has a unique atomic number, which is listed on the periodic table above the chemical symbol for the element. The atomic number is equal to the charge on the nucleus. The atomic number also equals the number of protons in the nucleus and the number of electrons in the neutral atom of the element.

For example, Fluorine (F) has the atomic number 9, which means that its atoms contain 9 protons and 9 electrons. Zinc (Zn) has the atomic number 30; its atoms contain 30 protons and 30 electrons.

1. Fill in the missing information in the table below. Use information from the periodic table to assist you, along with your text.

Protons	Neutrons	Electrons	Isotope Symbol
76	124
21	24	21

2. Give the atomic number and mass number of the following:

	Atomic number	Mass number
An aluminum atom with 12 neutrons
An atom with 17 protons and 20 neutrons

3. Cytoxan, also known as cyclophosphamide, is widely used alone or in combination in the treatment of certain kinds of cancer. It interferes with protein synthesis and in the process kills rapidly replicating cells, particularly malignant ones. Cytoxan has the molecular formula C7H15O2N2PCl2.

a. How many atoms are in one molecule of Cytoxan?

b. What elements are present in Cytoxan?

c. What is the ratio of hydrogen atoms to nitrogen atoms in Cytoxan?

4. How many valence electrons do each of the following elements have?

Element	Number of valence electrons
Carbon (C)
Potassium (K)
Beryllium (Be)
Fluorine (F)
Argon (Ar)

5. What is the relationship between the group number of an element and the number of valence electrons it contains?

For more help, visit the Extra! Extra! section of this unit for helpful resources on writing a thesis statement and solid introductory and conclusion paragraphs. Examples of effective strategies used in introductions and conclusions are provided to help you write a strong Assignment.