sec 2 lesson 3 chapter 3

In the structural formula of the opposite compound:What are the number of the valence electrons of the elements of this compound which do not participate in forming the bonds?...............

• 6

• 8

• 10

• 12

The Lewis structure for an atom of helium is shown below. Which of these statements explains why helium does not usually form chemical bonds?

• The first electron shell can hold eight electrons, but finding six electrons for a full valence shell is too difficult.

• The first electron shell can only hold two electrons; therefore, helium has a full valence shell.

• Helium is a gas and therefore cannot lose its two electrons.

The Lewis structure for a molecular compound of potassium and sulfur is shown below. How can you tell this compound is ionically bonded?

• Ionic compounds always contain atoms in a 2 : 1 ratio.

• The atoms are sharing electrons to obtain full outer shells but have not become ions.

• The atoms have either lost or gained electrons to become ions and obtain full outer shells.

The molecule …………… includes three bond pairs.

• HBr    

• H₂O

• NF₃

• O₂

In which of the following compounds the ionic character predominates?...............

• CH₃Cl

• CH₄

• Cl₂

• RbCl

Which of the following values represents the difference in electronegativity in a good electric conducting compound? ……………

• 0.4

• 1.2

• 1.5

• 2.1

The structures of most compounds can be classified as simple molecular, giant covalent, ionic, or metallic. All but one of the following compounds exhibit the same type of structure. For which compound is a different type of structure observed?

• MgBr2

• NaCl

• CH4 

An ionic compound is made from a metal,M and a nonmetal, X .The electron dot diagrams for M and X are shown below. Which of the following molecular formulas will the ionic compound have?

• M2X3

• M2X

• MX

• MX3

Which of the following accounts for the high melting point of ionic compounds?

• The electrostatic force of attraction between the oppositely charged ions

• Hydrogen bonding between negative and positive poles

• The forces that arise from sharing a pair of electrons

Why do ionic compounds conduct electricity in molten and aqueous phases but not in the solid phase?

• The ions are free to move in aqueous and molten phases but not in the solid phase.

• The electrons are free to move in aqueous and molten phases but not in the solid phase

• Bonds in solid ionic compounds are nonpolar, while bonds in molten and aqueous ones are polar.