covalent bonding Flashcards
(22 cards)
define covalent bonding
a covalent bond is the electrostatic attraction between the nuclei of two atoms and a shared pair of electrons
how do you show covalent bonding? (2 ways)
a) line structure
b) electron dot diagrams
what is an expanded octet?
when more than 4 pairs of electrons are shared/ more than 8 electrons in shell. (up to 9 pairs). This is why larger atoms are multivalent!
from what period onward do you get expanded octect?
period 3
what is a sigma bond and when does it form?
single bond. formed first. 1 electron pair shared between two atoms.
what are two types of bonds that can form?
sigma and pi
when is a pi bond formed?
after sigma bond. (double/ triple bond)
in a line structure, what must you always show (if present) around central atom?
lone pairs
what type of bonding do noble gases undergo and why? (3)
covalent bonding.
- They form expanded octets
- large atomic size
- their valence electrons are in the 5th shell which is far from the nucleus
can helium undergo bonding? why? (3)
no.
- small atom
- all electrons are paired
- force of attraction between electrons and nucleus are strong
what conditions are needed for Dative Covalent (coordinate) bonding to occur?
central atom must have a lone pair, and other atom must have an empty orbital.
explain dative covalent bonding in your own words
its when an atom donate both of its electrons as a bonding pair
what two molecules must you know how to show for dative covalent bonding?
NH₄⁺ and Al₂Cl₆
what are nitrogen oxides usually reffered to as? why?
pollutants. nitrogen has 3 unpaired electrons.
some nitrogen oxides have an unpaired electron. How does this affect the substance?
It makes it more reactive and easily combined with other substances (esp oxygen)
how does an orbital overlap affect a molecule? (3)
- greater overlap = stronger bond
- changes shape of molecule
- changes physical properties of substance
what do atomic orbitals do during covalent bonding?
They combine
how does a hybrid orbital form?
when different atomic orbitals combine/ overlap to form a new orbital. (single lobed)
from what overlap do sigma bonds form? Are they symmetrical or assymetrical?
- head on overlap (of s-s / p-p / s-p)
- symmetrical
from what overlap do pi bonds form? Are they assymetrical or symmetrical?
- sideways overlap (of only p-p)
- assymetrical
what are the three types of hybrid orbitals?
- sp3 (1s , 3p)
- sp2 (1s, 2p)
- sp (1s, 1p)
