AC-HPAT Chemistry 2023/2024 updated Questions and Answers 100% Correct

double-displacement reaction A double displacement reaction, also known as a double replacement reaction or metathesis, is a type of chemical reaction where two compounds react, and the positive ions (cation) and the negative ions (anion) of the two reactants switch places, forming two new compounds or products Precipitate precipitate is an insoluble solid that emerges from a liquid solution. The emergence of the insoluble solid from solution is called precipitation. Often the precipitate emerges as a suspension. Precipitates can form when two soluble salts react in solution to form one or more insoluble products. Energy Levels Energy levels (also called electron shells) are fixed distances from the nucleus of an atom where electrons may be found. As you go farther from the nucleus, electrons at higher energy levels have more energy. Electrons in the outermost energy level of an atom are called valence electrons Marquis Test The Marquis Test is commonly used for Ecstasy testing as MDMA turns the precipitate purple black. Cobalt thiocyanate is used to test for cocaine. The Cobalt is mixed with the questionable substance, then drowned in hydrochloric acid, doused in chloroform, and shaken. What is the relation between an atomic number and a mass number? Atomic number is actually the number of protons in an atom while mass number is the number of nucleons i. e, number of protons plus the number of neutrons. Isotopes Isotopes refer to the nuclides of a certain element that have different numbers of neutrons, or in other words, atomic nuclei that have the same number of protons but different numbers of neutrons. A radioisotope is an isotope that is unstable and therefore undergoes radioactive decay or will at some point