describe the trend across a period from left to right and within a group from top to bottom for the effective nuclear charge

Explanation:

The general trend is for ionization energy to increase moving from left to right across an element period. Moving left to right across a period, atomic radius decreases, so electrons are more attracted to the (closer) nucleus. The general trend is for ionization energy to decrease moving from top to bottom down a periodic table group.

in the analysis of systems that involve fluid flow, we frequently encounter the combination of properties u and pv.

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.