AC-HPAT Chemistry Latest Versions Graded A+

AC-HPAT Chemistry Latest Versions Graded A+ 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. Chemical Synthesis Chemical synthesis, the construction of complex chemical compounds from simpler ones. It is the process by which many substances important to daily life are obtained. It is applied to all types of chemical compounds, but most syntheses are of organic molecules. Decomposition A decomposition reaction is a type of chemical reaction in which a single compound breaks down into two or more elements or new compounds. These reactions often involve an energy source such as heat, light, or electricity that breaks apart the bonds of compounds single-displacement reaction A single-displacement reaction, also known as a single- replacement reaction, is a type of chemical reaction where an element reacts with a compound and takes the place of another element in that compound. This type of reaction is typically pictured like this: Here, A replaces B in the compound BC Flame test flame test is an analytical procedure used in chemistry to detect the presence of certain elements, primarily metal ions, based on each element's characteristic emission spectrum. The color of flames in general also depends on temperature; see flame color. Precipitation reaction A precipitation reaction refers to the formation of an insoluble salt when two solutions containing soluble salts are combined. The insoluble salt that falls out of solution is known as the precipitate, hence the reaction's name. Precipitation reactions can help determine the presence of various ions in solution. organic compounds An organic compound is a substance that is added to a product, like food, to improve some qualities such as taste, smell, colour and texture. These substances can be both positive and negative for human health. Synthetic materials Synthetic materials which are by-products of petroleum are non- biodegradable, synthetic products take a long time to decompose, creating long-term pollution. Nylon is hard to recycle, making them hard to decompose, accumulate landfills more. Polyesters are easy to recycle, which makes them less harmful to the society. Electronegativity Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. The Pauling scale is the most commonly used. Fluorine (the most electronegative element) is assigned a value of 4.0, and values range down to caesium and francium which are the least electronegative at 0.7.