Types of bonding Flashcards
Define sigma bonds
Bonds formed by linear overlapping (s-s bond, s-p bonds or p-p bonds)
Define Pi bonds
Bonds formed by parallel overlapping (only p-p bonds)
Give a definition for bond length
The distance between 2 nuclei
As the bond length increases, what happens to bond strength?
Bond strength decreases
As bond length increases, what happens to atomic size?
Atomic size increases
As bond length increases, what happens to bond order?
bond order decreases
Define electrongativity
The ability of an atm to attract the shared pair towards itself, giving it a partially negative charge.
Which atom has the highest electronegativity
Fluorine
What happens to electronegativity down a group?
Decreases
What happens to electrongetavity across a period?
Increases
By electronegativity difference what is the polarity of a molecule between 0 - 0.6
Non-polar
By electronegativity difference what is the polarity of a molecule between 0.6 - 1.6
Polar
By electronegativity difference what is the polarity of a molecule between 1.6 - + …
Ionic
If a molecule is polar/non-polar can it be ionic? (Yes/No)
No, all polar/non-polar molecules are covalently bonded.
Apart from electronegativity difference, how else can we see if a molecule is polar/non-polar? (4)
Non polar:
> All the atoms surrounding the central atom are the same. E.g. NH3 (Homoatomic)
> Hydrocarbon
Polar:
> Diff atoms around central atom
> Lone pairs found
In intermolecular forces, what do 2 polar molecules form?
a dipole-dipole force of attraction
In intermolecular foces, what do 2 non-polar molcules form?
Instantanious dipole-induced dipole force of attraction (London dispersion forces)
How do london dispersion forces come about?
When 2 non-polar molecules approach each other, their electrons repel allowing for a partially negative and positive molceule to form which attracts.
In intermolecular forces, which atoms does hydrogen need to approach for it to form hydrogen bonding?
Nitrogen, oxygen or fluorine
Why is hydrogen bonding the strongest form of intermolecular forces?
Because the atoms it forms intermolecular forces have lone pairs and it is more polar.
Rank the intermolecular forces from strongest to weakest:
dipole-dipole
hydrogen bonding
london dispersion
1) Hydrogen bonding
2) Dipole-Dipole
3) London Dispersion
Why can some london dispersion forces be stronger than others?
Stronger london dispersion forces have a larger surface area
What differentiates coordinate bonding (covalent) from hydrogen bonding (intermolecular force) (2)
1) Hydrogen bonding is much weaker than the covalent bonding of coordinate bonding
2) Covalent bonding includes sharing of electrons, while hydrogen bonding is purely from partial negative and positive attraction
Rank these in order of strongest to weakest:
Ionic, intermolecular forces, covalent, metallic
1) Ionic
2) Covalent
3) Metallic
4) Intermolecular
What type of bonding occurs in a single bond?
sigma
What type of bonding occurs in a double bond?
sigma & pi
What type of bonding occurs in a triple bond?
1 sigma & 2 pi
