Chemistry Homework #3- Pg 132

Pg 132 #26-28, 29-34 

26. Which are more likely to lose electrons, metallic or nonmetallic elements?

a.     Metallic elements

27. Noble gas elements rarely lose or gain electrons. What does this indicate about their chemical reactivity?

a.     They are completely unreactive with any other elements.

28. Predict whether each of the following elements would be more likely to form an anion or a cation:

a.     Na: Cation

b.     Ca: Cation

c.      F: Cation

d.     Cu: Cation

e.     O: Anion

f.      Li: Cation

g.     Sn: Anion

h.     I: Anion

29. Which pair is more similar chemically? Defend your choice:

a.     Copper metal and copper (II) ions

                                               i.     This pair is more similar chemically because when you have ions, the reaction with other chemicals isn’t affected, while if you have an isotope, the difference of mass can affect the properties of that element.

OR

b.     Oxygen with the mass number 16 and oxygen with the mass number 18. 

30. The diameter of a magnesium ion (Mg²⁺) is 156 pm (picometers, where 1 pm = 10^-12m); the diameter of a strontium ion (Sr²⁺) is 254 pm. Estimate the diameter of a calcium ion.

a.     The diameter is 205 pm (picometers)

31. Three kinds of observations that may indicate a chemical change appear in the following list. However, a physical change may also result in each observation. Describe a possible chemical cause and a possible physical cause for each observation:

a.     Change in color:

                                               i.     Chemical: reacting with an acid

                                              ii.     Physical: rusting

b.     Change in temperature:

                                               i.     Chemical: reaction with oxygen

                                              ii.     Physical: being heated

c.      Formation of gas:

                                               i.     Chemical: If you were to mix two elements such as Hydrochloric acid (HCl) and Carbon dioxide (CO₂)

                                              ii.     Physical: Reaching the boiling point of a substance

32. Identify the element that is described by each of the following statements:

a.     This element is nonmetal. It forms anions with a 1- charge. It is in the same period as the metals used in a penny.

                                               i.     Bromine (Br)

b.     This element is a metalloid. It is in the same periods as the elements found in table salt.

                                               i.     Silicon (Si)

33. Compare your use of the Snake River data to solve the fish-kill mystery in Unit 1 to Mendeleev’s use of element data to create the periodic table.

a.     Mendeleev’s use of the element data is similar to my use of the Snake River data because I only had a certain amount of information and had to make assumptions based upon the information I was given, similar to Mendeleev’s use of the information about the elements, such as their atomic weight, which he used in order to organized the periodic table.

34. Mendeleev arranged the elements in his periodic table in order of their atomic weights. In the modern periodic table, however, elements are arranged in order of their atomic numbers. Cite two examples from the periodic table for which these two schemes would produce a different ordering of adjacent elements.

a.     One scheme that would produce a different ordering of elements is if they were in alphabetical order based upon their symbol names.

b.     Another scheme that would produce a different ordering of the elements would be if they were organized based upon their element names.