P.SCI

• Chemical bonds are formed when atoms lose, gain, or share electrons
• An ionic bond occurs when there is a transfer of one or more valence electrons from one atom to another, existing between metal and nonmetal atoms
• In covalent bonds, two nonmetal atoms combine and share electron pairs
• NaCl, CaCl2, Fe2O3, KBr, and AlCl3 are ionic compounds, while CO2, CCl4, N2O, PCl5, and HCl are covalent compounds
• Polar covalent bonds form when electrons are shared unequally by two atoms in a compound, creating an electric dipole with a positive and negative end
• For polyatomic molecules, both the bond polarity and molecular shape determine the overall molecular polarity
• Valence shell electron pair repulsion (VSEPR) theory helps determine the spatial arrangement of atoms in a polyatomic molecule
• In symmetrical molecules, where the sum of the bond dipole is zero, the molecule is nonpolar; in asymmetrical molecules, it's polar
• NH3, CS2, and BCl3 are examples of polar covalent bonds
• The most polar bond is H-Cl
• The molecular shape of CHBr3 is tetrahedral
• A nonpolar covalent bond would be formed by P-N
• In the Lewis structure of NH3, there is 1 nonbonding pair of electrons around the central atom
• Polar covalent bonds can be present in a nonpolar molecule
• Electronegativity is the relative ability of a bonded atom to attract shared electron pairs
• Polar molecules have polar bonds arranged so that they do not cancel
• BF3 is an example of a tetrahedral molecule
• CO2 is not a polar molecule
• S and O are bonded by a polar covalent bond because their electronegativity difference value is 1.0 - FALSE
• Atoms with high electronegativity have a greater tendency to attract electrons toward themselves - TRUE
• Polarity of molecules is determined by both the polarity of bonds and molecular geometry - TRUE
• Among C-Cl, H-Cl, C-H, and Cl-Cl, only Cl-Cl is polar - FALSE
• Methyl alcohol, CH3OH, is a nonpolar molecule - FALSE
• SiCl4 is a nonpolar molecule - TRUE
• H2S has a linear molecular geometry - FALSE
• PF5 is a polar molecule - TRUE
• Polar bonds are formed when there is an unequal sharing of electrons between atoms, while nonpolar bonds are formed when there is equal sharing of electrons between atoms
• Electronegativity measures the tendency of an atom in a molecule to attract shared electrons towards itself and can be used to predict whether a bond will be polar or nonpolar
• Yes, a molecule can have a polar bond but have an overall polarity of nonpolar if its molecular geometry satisfies the condition of VSEPR theory
• Bonding electrons are involved in the formation of covalent bonds, while lone pairs (nonbonding electrons) are pairs of valence electrons not shared with another atom
• In NH3, the molecular shape is trigonal pyramidal, making it polar, while in BF3, the molecular shape is trigonal planar, making it nonpolar
• A molecule with an AB3E configuration will exhibit a trigonal bipyramidal shape and therefore be nonpolar