[Ng Jun Wei]

Hi im new here and im currently studying undergrad chem
  In chemical bonding, s and p orbitals can hybridize to form sp, sp2, sp3 hybridized orbitals to form sigma and pi bonds. My question is how can we correctly identify what hybridized orbitals will form for a given element in a molecule. eg. O in CO2 forms sp2 orbitals whereas O in H2O forms sp3 orbitals. Are we required to memorize and know these or is there a way to find out for any given molecule the hybridized orbitals that will form?

[Babcock_Hall]

Some textbooks teach this using a concept called "steric number." Is that a familiar term?

[Ng Jun Wei]

Some textbooks teach this using a concept called "steric number." Is that a familiar term?

Is that something to do with the shape of molecule due to the number of election pairs?

[chenbeier]

Normaly it is easy to remember. If you have only single bonds at your central atom it is sp³, if you have one doublebond its sp² and if you have two doublebonds or one triple bond then ist sp hybridised.

[Babcock_Hall]

The steric number of an atom is the number of atoms bonded to it plus the number of lone pairs that the atom has.  When it is four, the carbon has four sp³-hybridized orbitals.  When it is three, the carbon has three sp²-hybridized orbitals, and so forth.