u3: lewis structure Flashcards
1
Q
lewis bonding theory
A
- atoms are stable if they have a noble gas electron structure
- electrons are most stable when paired
- atoms form bonds to achieve stable octet
- stable octet achieved through electron transfer (metal+non-metal) or sharing (non-metals)
2
Q
where do leftover valence electrons go?
A
central atom
3
Q
which elements are exceptions to the octet rule?
A
- Be
- B
- P
- S
- Xe
4
Q
bond rules
A
- hydrogen and halogens (F, Cl, Br, I) form a single bond
- family oxygen (O, S, Se) forms 2 single bonds or 1 double bond
- family nitrogen (N, P, As) and boron forms 3 single bonds, 1 ingl bond+double bond, or a triple bond
- family carbon (C, Si) forms 4 single bonds, 2 double bonds, or…
5
Q
octet rule violation: Be
A
4
6
Q
octet rule violation: B
A
6
7
Q
octet rule violation: P
A
8 or 10
8
Q
octet rule violation: S
A
8, 10, or 12
9
Q
octet rule violation: Xe
A
8, 10, or 12
10
Q
coordinate covalent (dative) bond + example
A
- when one atom contributes a pair of electrons to form a bond
- NH4
11
Q
what can the central atom not be?
A
- usually not oxygen
- never hydrogen
12
Q
formal charge
A
calculated value used to compare number of valence electrons to number of electrons assigned to each atom in lewis structure
13
Q
what are formal charges used for?
A
to determine the best structure for an atom
14
Q
best lewis structure
A
- one with fewest charges
- puts negative charge on most electronegative atom
15
Q
lewis was doing his work at the same time as…
A
quantum mechanics was being developed
