HESI A2 CHEMISTRY, QUESTIONS WITHACCURATE ANSWERS. GRADED A+ LATEST UPDATE 2023

HESI A2 CHEMISTRY, QUESTIONS WITHACCURATE ANSWERS. GRADED A+ LATEST UPDATE 2023 Mixture with uniform density throughout and no distinguishable coponents. - Homogeneous Mixture Mixture in which the components are readily distinguished. - Heterogeneous Mixture A change in which the checmical composition of a substance remains the same. - Physical Change A change in which the chemical bonds are broken and reformed to create a new and different substance. - Chemical Change The simplest of substances and is represented by a specific letter or combinations of letters. - Element Combinations of eleements in whole number ratios. - Compounds Mass cannot be created or destroyed during a chemical reaction. - Law of Conservation of Mass The breaking of bonds and the reforming of new bonds to create new chemical compounds with different chemical forumulas and different chemical properties. - Chemical Reaction syntehesis, decomposition, combusion, single replacement, double replacement - Five main types of chemical reactions. Two elements combine to form a product. - Syntehsis Reaction The breaking of a compound into component parts. - Decomposition Reaction The reaction of a compound or element with oxygen. In the combusiton of a hydrocarbon carbon dioxide and water are produced. - Combustion Reaction Reaction involoving ionic compounds. The reactivity of the ionic compounds determines whether the reaction will take place or not. Can be single replacement or double replacement reaction. - Replacement Reactions Reaction between a more active metal reacting with an ionic compound containing a less active metal to produce a new compound ex. copper wire reacting with aqueous silver nitrate. - Single Replacement Reaction Reaction involving two ionic compounds where the positive ion from one compound combines with the negative ion of the other compound. The result it two new ionic compounds that have switches partners. - Double Replacement Reaction The number of protons in a given element. - Atomic Number An average of the masses of each of the iostopes of an element as they occur in mature. (Represents the number of protons and the number of neutrons in an element because electrons essentially have no mass). - Atomic Weight/ Atomic mass number What group has a +1 charge - IA What group has a +2 charge - IIA What group has a +3 charge - IIIA Density of an object realtive to water - Specific Gravity Energy of motion - Kinetic Energy Stored energy - Potential Energy Form of energy, measured in calories - Heat The amount of heat necessary to raise the temperature of 1g of water by 1 degree celsius. - Calorie Combination of two or more pure substances. - Mixture Atoms with the same number of protons but different numbers of neutrons. - Isotope Elements in group 8A of the periodic table. Have no charge and are gases under normal conditions. (Helium, Neon, Argon, Krypton, Xenon, Radon) - Noble Gases How many electrons fit in shells 1, 2, 3 & 4? - 2,8,18,32 Elements of group 7A. Have a charge of -1. Fluorine, Chlorine, Bromine, Iodine. Form compounds with sodium in the form NaX. - Halogens Elements of group 1A. Have a charge of +1. Lithium, Sodium, Potassium, Rubidium, Cesium. React with water to form hydrogen gas and a metal hydroxide (MOH) + H2. Also from compounds with the halogens in the form MX. Ex. NaCl. - Alkali Metals An ion with a negative charge. - Anion An ion with a positive charge. - Cation A chemical bond resulting from the attraction between a positive ion and a negative ion. - Ionic bond A chemical bond resulting from the sharing of electrons between two atoms. - Covalent Bond A covalent bond between two atoms where electrons are not shared equally between the two atoms. - Polar covlaent bond A bond that involves the attraction between oppositely charged ions. - Ionic Bond Attraction for a hydrogen atom by a highly electronegative element. Generally involve fluorine, chlorine, oxygen, and nitrogen. - Hydrogen bond. Temporary dipole created when moving electrons within an element or compound concentrate themselves on one side of an atom. Usually found in nonpolar covalent compounds. - Dispersion Forces Another name for dispersion forces, dipole interactions. - Van der Walls forces What group has a -3 charge - VA What group has a -2 charge - VIA What group has a -1 charge - VIIA How many known elements are there? - 109 Amount of an element equal to its atomic weight in grams. - Mole The emission of helium ions that consist of 2 protons and 2 neutrons (thus having a +2 charge). Can be stopped by a piece of paper. - Alpha Radiation The product of the decomposition of a neutron and is composed of high energy high-speed electrons. They are negatively charged and have basically no mass. Can be stopped by aluminum foil. - Beta Radiation High-energy electromagnetic radition that lacks charge and mass. Can be stopped by several feet of concrete or several inches of lead. - Gamma Radiation The emission of particle sfrom an unstable nucleus. Exists in three forms alpha, beta, and gama radiation. - Radioactivity The mass of one mole of a compound. - Molar mass When a substance changes from a solid to a gas without first becoming a liquid. - Sublimation PV=nRT (n is equal to the number of moles of the substance and R is the gas constant 0.082) - Ideal gas law The number of moles of solute in 1 liter of solution. - Molarity