Do these look right?
What shape does an ammonia (NH3) molecule have?trigonal pyramidal
In a tetrahedral molecule, how many unshared pairs of valence electrons does the central atom have? none
In a polar bond, electrons are? completely transferred
What determines the polarity of a bond? molecular shape only
What determines the polarity of a molecule?electronegativity difference only
What shape does an ammonia (NH3) molecule have?trigonal pyramidal
correct
In a tetrahedral molecule, how many unshared pairs of valence electrons does the central atom have? none
This answer is correct for AB4 type molecules in which the central atom has a valence of 4 and each bond has a element (in this case B) attached.
In a polar bond, electrons are? completely transferred
OK
What determines the polarity of a bond? molecular shape only
No. The polarity of a bond is determined by the electronegativity difference between the two elements forming the bond
What determines the polarity of a molecule?electronegativity difference only
No. The net polarity (net dipole moment) of a molecule is determined by two things:
a. The polarity of individual bonds, AND
b. the symmetry of the molecule.
To have a net dipole moment, a molecule MUST have both (a) individual bond polarity AND (b)the molecule must NOT be symmetrical.
To verify whether the given answers are correct, let's go through the explanation for each question:
1. What shape does an ammonia (NH3) molecule have? - The shape of an ammonia molecule is indeed trigonal pyramidal. To determine this, one needs to know the Lewis structure of the molecule, which indicates that it consists of three hydrogen atoms bonded to a central nitrogen atom. The presence of one lone pair of electrons on the nitrogen atom pushes the hydrogen atoms down, leading to a pyramid-like shape.
2. In a tetrahedral molecule, how many unshared pairs of valence electrons does the central atom have? - The answer, none, is correct. In a tetrahedral molecule, the central atom is bonded to four other atoms with no lone pairs of electrons. Each bond involves sharing a pair of electrons, leaving no unshared pairs on the central atom.
3. In a polar bond, electrons are? - The given answer, completely transferred, is not correct. In a polar bond, electrons are not completely transferred but are shared unequally between the atoms involved. This unequal sharing leads to partial positive and partial negative charges on the atoms, creating polarity in the bond.
4. What determines the polarity of a bond? - The answer, molecular shape only, is incorrect. The polarity of a bond is determined by two factors: electronegativity difference and molecular shape. Electronegativity is the ability of an atom to attract electrons towards itself. If there is a significant difference in electronegativity between the atoms in the bond, it will be polar. However, the molecular shape also plays a role as it can influence the overall polarity of the molecule.
5. What determines the polarity of a molecule? - The given answer, electronegativity difference only, is incorrect. The polarity of a molecule is determined by both electronegativity difference and molecular shape. The electronegativity difference between atoms determines the polarity of individual bonds within the molecule. However, the overall molecular shape, taking into account the arrangement of bonds and any lone pairs of electrons, also contributes to the overall polarity of the molecule.
In summary, the correct answers are:
1. What shape does an ammonia (NH3) molecule have? - Trigonal pyramidal
2. In a tetrahedral molecule, how many unshared pairs of valence electrons does the central atom have? - None
3. In a polar bond, electrons are? - Unequally shared
4. What determines the polarity of a bond? - Electronegativity difference and molecular shape
5. What determines the polarity of a molecule? - Electronegativity difference and molecular shape