PHY S 100 Lesson 22

What is the charge of iron (Fe) in the compound Fe2O3?

+3

How many more electrons does unbound oxygen need to fill its 2nd shell? (You may find it helpful to draw the energy well on scratch paper.)

2

Which of the following is a correct and balanced equation showing the reaction of calcium and oxygen? (While several of the equations may be balanced, only one has the correct products and reactants as well as being correctly balanced.)

2Ca + O2 = 2CaO

What happens to the entropy of the universe as the products are formed?

Chemical potential energy is converted into thermal energy resulting in an increase in entropy.

Which of the following would best describe the room-temperature characteristics of an ionic substance?

brittle, transparent, electrically non-conducting solid

In lesson 20, a magnesium strip was used to ignite the thermite reaction. When magnesium is placed in a flame from a small blow torch, it burns quite brightly, forming magnesium oxide, a salt that contains one magnesium for every oxygen. The following questions ask you to provide some details of the chemical processes involved in a reaction between magnesium and oxygen. An energy diagram for the magnesium-oxygen reaction is shown to the right. Sodium will also react with oxygen. However, unlike magnesium, sodium reacts immediately when it is exposed to oxygen and produces very little heat and no visible light. Which of the curves below best represents the sodium-oxygen reaction compared with the magnesium-oxygen reaction to the right? (The curve for magnesium + oxygen is shown in light grey for reference.)

?

Which of the following is an ionic compound?

MgF2

What happens to the valence electrons as the product (MgO) is formed?

The magnesium atoms' valence electrons are effectively transferred to oxygen.

What happens to the valence electrons as an ionic compound is formed?

The metal atoms' valence electrons are effectively transferred to the nonmetal.

Which of the following would best describe the room temperature characteristics of the substance that results from the reaction between magnesium (Mg) and oxygen (O)?

a brittle, transparent, electrically non-conducting solid

Ionic compounds are formed between a metal and a

nonmetal

The oxidation state of an atom refers to

the number of electrons gained or lost when an ionic bond is formed.

octet rule

when an ion forms, it is most energetically favorable to get to a noble gas configuration of ns2np6.