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1
What is the primary purpose of a Lewis formula (Lewis structure) in chemistry?
A
To show the three-dimensional shape of a molecule
B
To represent the arrangement of valence electrons in a molecule or ion
C
To indicate the types of intermolecular forces present
D
To calculate the molar mass of a compound
2
When drawing a Lewis structure for a molecule, which electrons are represented in the structure?
A
Only the electrons in the innermost shell
B
Only the valence electrons
C
Only the unpaired electrons
D
All electrons in the atom
3
How is the total number of valence electrons determined for a polyatomic ion such as SO₄²⁻?
A
Sum the valence electrons of all atoms and subtract 2 for the negative charge
B
Sum the valence electrons of all atoms and add 2 for the negative charge
C
Sum the valence electrons of all atoms only
D
Sum the valence electrons of all atoms and add 2 for each oxygen atom
4
For a cation such as NH₄⁺, how should the total valence electron count be adjusted?
A
Do not adjust; use the sum of valence electrons only
B
Add one electron for the positive charge
C
Subtract one electron for the positive charge
D
Add one electron for each hydrogen atom
5
In a Lewis structure, what does a line between two atoms represent?
A
An ionic bond
B
A lone pair of electrons
C
A single electron
D
A shared pair of electrons (a single covalent bond)