Homework: Atomic Structure,
additional practice

1. One isotope of a neutral metallic element has mass number 65 and 35 neutrons in its nucleus. Write the symbol for this isotope.
2. Fill in the blanks in the following table:

   Name	Symbol	Z Atomic Number No. of p+	A - Z No. of n0	A Mass Number	No. of e–	Charge
   iron-54	5426Fe2+
   		5	6			0
   			16		15	0
   		79	117		78
   radon-222			136			+3

3. One isotope of a nonmetallic element has mass number 127 and 74 neutrons in its nucleus. Write the symbol for this isotope.
4. Which of the following symbols provides more information about the isotope? ²⁴    Mg or   ₁₂Mg? Explain.
5. Fill in the following table.

   Name	Symbol	Z Atomic Number No. of p+	A - Z No. of n0	A Mass Number	No. of e–	Charge
   		5	5			+3
   		7	7			–3
   		19	18			+1
   		30		66	28
   		35		81		–1
   		35		79		0
   		19		39	18
   			24	46	18
   			28	50		+4
   			64	111		+1

6. What are atoms of the same element with different mass numbers called? What is the main reason atoms of the same kind can have different mass numbers?
7. You have learned about the parts of atoms. Now remember what you have learned about sub-atomic particles. Fill in the following table with the mass expressed in atomic mass units (amu).
   

   	Mass	Symbol	Charge
   proton
   neutron
   electron

8. Numbers are used to describe the parts of an atom. One of these numbers essentially determines the kind of atom. What number is it?
9. What are the two numbers used to describe atoms which can be changed without altering the type of atom?
10. What has changed in an atom that has become an ion?
11. How is the charge of an ion calculated? Give a simple equation.
12. Consider three atoms with atomic mass numbers 20, 21, and 22. Explain how these atoms could be the same element despite the difference in mass. What element or elements could these atoms be?
13. Why are the elements placed in the periodic table in order by atomic number and not atomic mass?
14. What is a period in the periodic table? How many are there?
15. What period does the element neodymium (Nd) belong to? What period does the element uranium (U) belong to?
16. What is a group in the periodic table? What do you know about the chemical and physical properties of the elements in a group?
17. Draw a picture of an atom of nitrogen-15 with a charge of –3. Clearly indicate in your drawing the number of each type of subatomic particle and its relative location in the atom.