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Lewis structures & molecule shapes. AB or AB 2 – linear. If there are only two atoms the shape will be linear – there are no unshared electrons around the central atom H 2 is a great example of linear, as is HCl CO 2 is also linear. AB 3 – Trigonal Planar.
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AB or AB2 – linear • If there are only two atoms the shape will be linear – there are no unshared electrons around the central atom • H2 is a great example of linear, as is HCl • CO2 is also linear
AB3 – Trigonal Planar • There are three atoms and the central atom does not have any unshared pairs of electrons • BF3 is an example, so is CH2O • The Lewis Structure will have 3 pairs around the central atom being shared with other atoms, and no other electrons around the central atom!
AB4 - Tetrahedral • There are four atoms bonded to the central atom with no unshared pairs of electrons on the central atom. • CH4 is an example • The Lewis Structure will have 4 pairs of electrons shared between the central atom and other atoms, with no other electrons around the central atom!
AB3E – Trigonal Pyramidal • Three atoms are bonded to the central atom, and the central atom has one pair of unshared electrons. • NH3 is an example • The Lewis Structure will have one unshared pair of electrons around the central atom as well at the other three pairs bonded to the three atoms
AB2E or AB2E2 – Bent or Angular • The central atom has two atoms bonded and two pair of unshared electrons • H2O is an example • The Lewis Structure will have two unshared pair of electrons around the central atom and two other pairs of electrons bonded to other atoms
Practice • Draw the Lewis Structure (or electron dot diagram) and then determine the shape for the following molecules • AlF3 • SiO2 • SF2 • PCl3
Practice • Draw the Lewis Structure (or electron dot diagram) and then determine the shape for the following molecules • AlF3 AB3 Triagonal Planar • SiO2 AB2 Linear • SF2 AB2E2 Bent or Angular • PCl3 AB3 ETriagonal Pyramidal
Practice • Draw the Lewis Structure (or electron dot diagram) and then determine the shape for the following molecules • CHF3 • CO2 • COF2 • GaBr3 • Na2S
Practice • Draw the Lewis Structure (or electron dot diagram) and then determine the shape for the following molecules • CHF3 AB4 Tetrahedral • CO2 AB2 Linear • COF2 AB3 Triagonal Planar • GaBr3 AB3 Triagonal Planar • Na2SAB2E2Bent
Practice • Draw the Lewis Structure (or electron dot diagram) and then determine the shape for the following molecules • NF3 • CO3-2 • CF4 • POH • C2H2
Practice • Draw the Lewis Structure (or electron dot diagram) and then determine the shape for the following molecules • NF3 AB3E Trigonal Pyramidal • CO3-2AB3 Triagonal Planar • CF4 AB4Tetrahedral • POHAB2EBent • C2H2 AB2 Linear (both carbons)