Prepare for the HESI A2 Chemistry section with this study guide and practice questions. This guide covers atomic structure, chemical bonds, reactions, and solution chemistry.
Q: Absorption
Answer: the process by which a substance is soaked up
Q: What are Acids
Answer: – act as hydrogen-ion donors- produce H3O+ in aqueous solutions- tast sour or tart- most of their formulas begin with H- relase H2 gas when reacting with active metals- conduct electrical current- pH is less than 7
Q: Acidic Solution
Answer: A solution with a pH lower than 7
Q: Acid salt
Answer: An acid salt contains at least one hydrogen ion and can behave as an acid in a chemical reaction. Acid salts are produced under conditions that do not allow the complete neutralization of the acid
Q: Alkali Metals
Answer: 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.
Q: Activation energy
Answer: the energy required to make a reaction occur. The greater the activation energy of a reaction, the more it’s reaction rate depends on temperature
Q: Alcohol
Answer: an organic compound which contains a hydroxuyl (OH) group. Ex Ethanol CH3CH2OH). aka ethanol or grain alcohol
Q: Alkali / Alkaline
Answer: A base in a (aqueous) solution. Alkalais react with, or neutralize hydrogen ions in acids and have a pH greater than 7.0 because they contain relatively few hydrogen ions
Q: Alkali metals
Answer: A member of group 1 of the periodic table. ex Sodium
Q: Alkane
Answer: a hydrocarbon with no carbon to carbon multiple bonds, ex Ethane C2H6
Q: Alkene
Answer: a hydrocarbon with at least one carbon to carbon double bond, ex Ethene C2H4
Q: Alkyne
Answer: A hydrocarbon with at least one carbon to carbon triple bond ex, Ethyne C2H4
Q: Alloy
Answer: a mixture of metal and various other elements. Ex brass is an alloy of copper and zinc
Q: Anhydrous
Answer: lacking water, water has been removed, for example by heating
Q: Anion
Answer: a negatively charged ion
Q: Atmospheric pressure
Answer: the pressure exerted by the gases in the air
Q: Atom
Answer: The smallest molecule of an element, a nucleus and its surrounding electrons
Q: Atomic Number
Answer: also known as the proton number. The number of protons in an atom
Q: Atomic Weight/ Atomic mass number
Answer: 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).
Q: Base
Answer: – produce OH- in solution- taste bitter- feel slippery-conduct electricity- formulas often contain OH– pH is greater than 7
Q: Bond
Answer: chemical bonding is either a transfer or sharing of electrons by two or more atoms.
Q: Strongest Chemical Bond
Answer: Covalent and then Ionic
Q: Weakest Chemical Bond
Answer: Hydrogen bond
Q: Boyle’s Law
Answer: At constant temperature, and for a given mass of gas, the volume of gas is inversely proportional to the pressure that builds up
Q: Buffer
Answer: A mixture of substances in a solution that resists a change in the acididy or alkalinity of the solution when small amounts of an acid or alkali is added
Q: Catalyst
Answer: a substance that speeds up a chemical reaction, but itself remains unaltered at the end of the reaction
Q: Celsius scale
Answer: a temp scale on which the freezing point of water is at 0 and the normal boiling point in standard atmosphere is 100.
Q: Change of state
Answer: a change between two of the three states of matter.
Q: Charles Law
Answer: the volume of a given mass of gas at constant pressure is directly proportional to it’s absolute temp
Q: Combustion Reaction
Answer: The reaction of a compound or element with oxygen. In the combusiton of a hydrocarbon carbon dioxide and water are produced.
Q: Compound
Answer: a chemical made of 2 or more elements chemically bonded together
Q: Condensation
Answer: the formation from a liquid to a gas
Q: Convection
Answer: the exchange of heat energy with the surroundings produced by the flow of a fluid due to being heated or cooled
Q: Covalent Bond
Answer: This is the most common and strongest form of chemical bonding. A chemical bond resulting from the sharing of electrons between two atoms.
Q: Density
Answer: The mass of unit per volume D=M/V
Q: DIffusion
Answer: The slow mixing of one substance with another until the two substances are evenly mixed. Moving from high concentration to lower.
Q: Electron
Answer: a tiny negatively charged particle that is part of an atom.
Q: Electron Configuration
Answer: The pattern in which electrons are arranged in the shells around the nucleus of an atom
Q: Element
Answer: a substance that cannot be broken down into anything simpler by chemical means
Q: Ester
Answer: Organic compounds formed by the reaction of an alcochol with an acid and often have a fruity taste
Q: What is Gamma radiation
Answer: High-energy electromagnetic radition that lacks charge and mass. Gamma radiation can be stopped by several feet of concrete or several inches of lead.
Q: Calculating the number of neutrons in a given isotope of an element.
Answer: Subtract the atomic number from the mass number.
Q: Charge of Elements in Group IA (1A)
Answer: +1
Q: Charge of Elements in Group IIA (2A)
Answer: +2
Q: Charge of Elements in Group IIIA (3A)
Answer: +3
Q: Charge of Elements in Group VA (5A)
Answer: -3
Q: Charge of Elements in Group VIA (6A)
Answer: -2
Q: Charge of Elements in Group VIIA (7A)
Answer: -1
Q: Chemical Change
Answer: A change in which the chemical bonds are broken and reformed to create a new and different substance.
Q: Chemical Reaction
Answer: The breaking of bonds and the reforming of new bonds to create new chemical compounds with different chemical forumulas and different chemical properties.
Q: Decomposition Reaction
Answer: The breaking of a compound into component parts.
Q: Dipole
Answer: Created when atoms are joined by a polar covalent bond. The positive end of a dipole in one compound will be attracted to the negative dipole in another compound creating weak attraction between the two compounds.
Q: Dispersion Forces
Answer: Temporary dipole created when moving electrons within an element or compound concentrate themselves on one side of an atom. Usually found in nonpolar covalent compoun
Q: Double Replacement Reaction
Answer: 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.
Q: Electron Shell Configuration
Answer: Shell Electrons (max)1) 22) 83) 184) 32
Q: The 5 main types of chemical reactions
Answer: syntehesis, decomposition, combusion, single replacement, double replacement
Q: Heat
Answer: A form of energy measured in calories
Q: Halogens
Answer: Elements of group 7A. Have a charge of -1. Fluorine, Chlorine, Bromine, Iodine. Form compounds with sodium in the form NaX.
Q: Heterogenous Mixture
Answer: Mixture in which the components are readily distinguished.
Q: Homogeneous Mixture
Answer: Mixture with uniform density throughout and no distinguishable coponents.
Q: How do you calculate DENSITY
Answer: d=m/v
Q: How many known elements are there
Answer: 109
Q: Hydrogen Bond
Answer: Attraction for a hydrogen atom by a highly electronegative element. Generally involve fluorine, chlorine, oxygen, and nitrogen.
Q: Ideal Gas Law
Answer: PV=nRT (n is equal to the number of moles of the substance and R is the gas constant 0.082)
Q: Ionic Bond
Answer: A chemical bond resulting from the attraction between a positive ion and a negative ion.
Q: Isotope
Answer: Atoms with the same number of protons but different numbers of neutrons.
Q: Kinetic Energy
Answer: Energy of Motion
Q: Law of Conservation of Mass
Answer: Matter can neither be created or destroyed
Q: Mixture
Answer: The combination of two or more pure substances
Q: Molar Mass
Answer: The mass of one mole of a compound
Q: Molarity
Answer: The number of moles of solute in 1 liter of solution.
Q: Neutralization
Answer: Process which occurs when an acid and a base react tot produce a salt and water. The result is a pH near 7
Q: Noble Gases
Answer: Elements in group 8A of the periodic table. Have no charge and are gases under normal conditions. (Helium, Neon, Argon, Krypton, Xenon, Radon)
Q: Oxidation
Answer: The loss of electrons in an redox reaction.
Q: Physical Change
Answer: A change in which the checmical composition of a substance remains the same. Ex Cutting a cake
Q: Polar Covalent Bond
Answer: A covalent bond between two atoms where electrons are not shared equally between the two atoms.
Q: Potential Energy
Answer: Stored Energy
Q: Radioactivity
Answer: The emission of particle sfrom an unstable nucleus. Exists in three forms alpha, beta, and gama radiation.
Q: Redox Reaction
Answer: Reactions that involve the transfer of electrons from one element to another.
Q: Reduction
Answer: The gain of electrons in a redox reaction
Q: Replacement Reaction
Answer: 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.
Q: Rules for determining oxidation state
Answer: 1. Elemental atoms have an oxidation number of zero.2. The oxidation number of any simple ion is the charge of the ion.3. The oxidation number for oxygen in compound is always -2.4. The oxidation number for hydrogen in compound is +1.5. The sum of the oxidation numbers equals the charge on the molecule or polyatomic ions.
Q: Single Replacement Reaction
Answer: 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.
Q: Specific Gravity
Answer: Density of an object realtive to water. No units.
Q: What is the strongest of intermolecular forces
Answer: Hydrogen Bond
Q: Strongest type of Chemical Bond
Answer: Covalent Bond
Q: Sublimation
Answer: When a substance changes from a solid to a gas without first becoming a liquid.
Q: Synthesis Reaction
Answer: Two elements combine to from a product
Q: Van der Walls forces
Answer: Another name for dispersion forces, dipole interactions.
Q: Weakest of intermolecular forces
Answer: Dispersion forces
Q: Weakest type of chemical bond
Answer: Ionic
Q: What is a mole
Answer: An amount of an element equal to its atomic weight in grams. Also described by the amount of a substance that contains 6.02 x 10 23rd particles of that substance.
Q: What is Alpha Radiation
Answer: The emission of helium ions that consist of 2 protons and 2 neutrons (thus having a +2 charge). Alpha particles can be stopped by a piece of paper.
Q: What is Beta Radiation
Answer: 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. Beta particles can be stopped by aluminum foil.
Q: What is Gamma Radiation
Answer: High-energy electromagnetic radition that lacks charge and mass. Gamma radiation can be stopped by several feet of concrete or several inches of lead