The figure that follows shows ball-and-stick drawings of three possible shapes of an AF3 molecule.
(a) For each shape, give the electron-domain geometry on which the molecular geometry is based.
(b) For each shape, how many nonbonding electron domains are there on atom A?
(c) Which of the following elements will lead to an \(\mathrm{AF}_{3}\) molecule with the shape in
(ii): Li, B, N, Al, P, Cl?
(d) Name an element A that is expected to lead to the \(\mathrm{AF}_{3}\) structure shown in (iii).
Text Transcription:
AF_3
Step 1 of 5) In a two-dimensional lattice, the unit cells can take only one of the five shapes shown in Figure 12.4. The most general type of lattice is the oblique lattice. In this lattice, the lattice vectors are of different lengths and the angle g between them is of arbitrary size, which makes the unit cell an arbitrarily shaped parallelogram. The square lattice, rectangular lattice, hexagonal lattice,** and rhombic lattice have a unique combination of g angle and relationship between the lengths of lattice vectors a and b (shown in Figure 12.4). For a rhombic lattice an alternative unit cell can be drawn, a rectangle with lattice points on its corners and its center (shown in green in Figure 12.4). Because of this the rhombic lattice is commonly referred to as a centered rectangular lattice. The lattices in Figure 12.4 represent five basic shapes: squares, rectangles, hexagons, rhombuses (diamonds), and arbitrary parallelograms. Other polygons, such as pentagons, cannot cover space without leaving gaps, as Figure 12.5 shows.
