What can the period number of an element tell us about that element?

Chen drew a diagram to compare the ways in which different organisms obtain nitrogen. which label belongs to the area marked z?

The table lists the lattice energies of some compounds.compoundlattice energy (kj/mol)lif            –1,036licl            –853naf            –923kf            –821nacl            –786which statement about crystal lattice energy is  best  supported by the information in the table? the lattice energy increases as cations get smaller, as shown by lif and kf.the lattice energy increases as the cations get larger, as shown by lif and licl.the lattice energy decreases as cations get smaller, as shown by nacl and naf.the lattice energy decreases as the cations get smaller, as shown by naf and kf.

How does kepler second law of planetary motion overthrow one of the basic beliefs of classical astronomy