Covalent Bond Basics
State why atoms form bonds in the first place.
To achieve stability by gaining a full electron shell.
What does the prefix "di-" mean in a molecular compound name?
Two atoms of that element.
Identify the atom that will never be the central atom in a Lewis Structure.
Hydrogen.
Draw the Lewis Structure for water. Identify the shape.
Bent
How does electronegativity change across a period?
It increases left to right.
Why do noble gases seldom form compounds?
They already have a full valence shell.
Why do we add the suffix “-ide” to the second element in a binary molecular compound?
To indicate it is the second element and to distinguish it from the first.
What is the second step when drawing a Lewis structure?
Count total valence electrons in the compound.
Why do lone pairs reduce bond angles more than bonding pairs?
Lone pairs repel more strongly because they are closer to the nucleus.
What do δ+ and δ– represent in a bond?
Partial positive and partial negative charges due to unequal sharing of electrons.
What is the main difference between a covalent bond and an ionic bond?
Ionic bonds transfer electrons and covalent bonds share electrons.
How can you tell from a formula whether a compound is an acid?
Formula begins with the letter H.
When must lone pairs be converted into double or triple bonds?
When the central atom does not achieve a full octet with single bonds alone.
What is the molecular shape of methane (CH₄)?
Tetrahedral.
What electronegativity difference indicates a polar covalent bond?
A moderate difference (typically 0.3–1.7).
Why do nonmetals tend to form covalent bonds with each other?
They have similar electronegativities and both want to gain electrons, so they share instead.
How do you name binary acids?
"hydro + root + ic + acid".
Determine the Lewis Structure for NH3
H -- N: -- H
|
H
Determine the shape of CCl4
Tetrahedral
Determine the electronegative difference between carbon and chlorine.
0.5
Why are triple bonds shorter and stronger than double and single bonds?
More shared electron pairs pull atoms closer together, increasing bond strength and decreasing length.
What is the formula for iodous acid and how do you know?
HIO₂ — “ous” corresponds to the “ite” oxyanion (IO₂⁻)?
Why are molecules with an odd number of valence electrons exceptions to the octet rule?
They cannot distribute electrons evenly to give all atoms an octet.
Compare NH₃ and H₂O: why do they have different shapes?
NH₃ has one lone pair (trigonal pyramidal); H₂O has two lone pairs (bent).
Why is carbon tetrachloride (CCl₄) nonpolar even though its bonds are polar?
Its tetrahedral shape is symmetrical