Unit 2.1-2.4

Which is NOT TRUE about electronegativity?

• a measure of the ability of an atom (or group of atoms) to attract shared electrons

• increases across a period because atomic radius is decreasing while number of protons is increasing

• decreases down a group because there's a greater distance from the nucleus and more electron shielding

• chlorine is the most electronegative element

Answer explanation

Fluorine is the most electronegative element

Define polar covalent bond

• transfer of electrons

• equal sharing of electrons

• unequal sharing of electrons

• delocalized sea of valence electrons

Define nonpolar covalent bond

• transfer of electrons

• equal sharing of electrons

• unequal sharing of electrons

• delocalized sea of valence electrons

Define ionic bond

• transfer of electrons

• equal sharing of electrons

• unequal sharing of electrons

• delocalized sea of valence electrons

Define metallic bond

• transfer of electrons

• equal sharing of electrons

• unequal sharing of electrons

• delocalized sea of valence electrons

What type of bond?

H-H

• nonpolar covalent bond

• polar covalent bond

• ionic bond

• metallic bond

Answer explanation

a) Difference in electronegativity:

2.1-2.1=0

b) both nonmetals=covalent

What type of bond?

C-H

• nonpolar covalent bond

• polar covalent bond

• ionic bond

• metallic bond

Answer explanation

a) Difference in electronegativity:

2.5-2.1=0.4

b) both nonmetals=covalent

What type of bond?

Na-Cl

• nonpolar covalent bond

• polar covalent bond

• ionic bond

• metallic bond

Answer explanation

a) Difference in electronegativity:

3.0-0.9=2.1

b) metal + nonmetal = ionic

What type of bond?

Fe-Fe

• nonpolar covalent bond

• polar covalent bond

• ionic bond

• metallic bond

Answer explanation

a) Difference in electronegativity:

1.8-1.8=0 BUT...

b) metal + metal = metallic

Which of the following is not a property of ionic substances?

• high melting and boiling points

• form crystals

• conduct electricity when dissolved and molten

• good insulators when solid

• high malleability and ductility