CHEMICAL BONDING Flashcards
what is an ionic bond?
strong electrostatic attraction between two positively charged ions
what is a covalent bond?
-it is a bond formed by a shared pair of electrons between the nuclei
-electrostatic attraction between positively charged nuclei of the bonded atoms and the negative electrons between these nucleus holds the atom together.
what is a dative covalent bond?
-a covalent bond whereby both electrons in the shared pair are donated by one of the bonding atom only.
what is a sigma bond?
-it is the strongest type of covalent bond
-formed from the head-on overlaps of the orbital
what is a pi bond?
also explain how’s it formed in carbon-carbon bond.
-bond formed weaker than sigma bond
-formed by sideway overlap
-a carbon-carbon pi bond is formed from the sideway overlap of p-orbitals above and below the plane
how does hybridization to form sp3 orbital form? eg: CH4
-a 2s electron would be promoted to a 2p orbital
-electrons then rearrange themselves via hybridization into four identical orbitals called the sp3 orbital.
-these four orbitals can then take part in bonding with hydrogen to form methane, CH4
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how does the hybridization to form sp orbital occurs? eg: C2H2
-a 2s electron would be promoted to 2p orbital
-hybridization occurs for 2 out of 4 orbitals
-these two orbitals, sp hybrids are now equal
how does hybridization to form sp2 occurs? eg: carbon in ethene
-a 2s electron would be promoted to 2p orbital
-hybridization occurs for 3 out of 4 orbitals
-these two orbitals, sp2 hybrids are now equal
what is electron repulsion theory?
-electron pairs repel themselves, meaning they distance themselves as far as possible.
-all bonding electron pairs repel each others equally
-lone pair offer more repulsion than bonded pair
what is electronegativity?
the ability of an atom to attract the bonding pair of electrons in a covalent bond
what is hydrogen bonding?
-it is the strongest intermolecular force
-a type of pd-pd interaction
-occurs when hydrogen atom is bonded to a very electronegative atom (fluorine, oxygen or nitrogen), which is close to another electronegative atom that has a lone pair of electrons
what is bond energy?
measure of the strength of a chemical bond
what is bond length?
average distance between the nuclei of the two bonded atom
what is bond polarity?
-when two different atoms are joined by a covalent bond
-the electronegativities of these atom would be different
-meaning that the electron would be drawn towards the atom with the greatest electronegative value
-this atom would have a slightly negative charge, while the other would be slightly positive
-the charge difference is a dipole
-if a bond is polar, it has a dipole
why non-metal oxide undergo hydrolysis ?
-oxygen is very electronegative
-as a result, a permanent dipole forms across the bond and the atom that oxygen is bonded to becomes partially positive
-when the oxide is added to the water, pairs on the oxygen in the water are attracted to the partially positive in the oxide causing a hydrolysis
