CHM209 MIDTERM EXAM 2025

Molecular Gastronomy - Correct Ans-seeks to investigate and explain the chemical reasons behind the transformation of ingredients, as well as the social, artistic, and technical components of culinary and gastronomic phenomena (founders Herve This and Nicholas Kurti) 2 parts of the atom - Correct Ans-nucleus and electrons nucleus - Correct Ans-dense centre of an atom that is positively charged and is made up of PROTONS and NEUTRONS electrons - Correct Ans-NEGATIVELY charged particles that are responsible for chemical structures and reactions how are electrons held in orbit around the nucleus? - Correct Ans-by the attraction between opposite (+ and -) charges atomic number (Z) - Correct Ans-the number of protons within the nucleus of an atom (determines the element and how many electrons a neutral atom has) mass number (A) - Correct Ans-the sum of the number of neutrons and protons in an atomic nucleus Ions - Correct Ans-atoms that have lost or gained one or more electrons cation - Correct Ans-A positively charged ion (lost electrons) isotopes - Correct Ans-Atoms with the same number of protons but different numbers of neutrons (different masses but behave the SAME chemically) SAME ELEMENT - Correct Ans-an atom with the same number of protons, could have different number of neutrons anion - Correct Ans-A negatively charged ion (gained electrons) compound - Correct Ans-a substance made up of more than one type of atom ionic compounds - Correct Ans-contain more than one type of ion (at least one type of cation and one type of anion) covalent bond - Correct Ans-two toms linked together through the sharing of two electrons molecule - Correct Ans-two or more atoms are stably joined by covalent bonds what happens to covalent compounds in water? - Correct Ans-the molecules dissolve in water how are grams and liters related? - Correct Ans-through density what do moles (mol) describe? - Correct Ans-the total amount of molecules g/mol - Correct Ans-the unit of measurement for molecular mass the abundance of a certain molecule in a defined volume or space - Correct Ans-concentration (molarity) the scientific method - Correct Ans-1. hypothesis 2. experiments 3. experimental results 4. theory what does water repulse? - Correct Ans-fats and oils Sublimation - Correct Ans-solid to gas freezing - Correct Ans-liquid to solid evaporation - Correct Ans-Liquid to gas melting - Correct Ans-solid to liquid electronegativity - Correct Ans-the ability of an atom to attract shared electrons in a covalent bond toward itself what does higher electronegativity mean - Correct Ans-stronger attraction for electrons non-polar covalent bonds - Correct Ans-between atoms with identical or similar EN, a difference of less than or equal to 0.5 polar covalent bonds - Correct Ans-EN difference of 0.5-2 Ionic bonds - Correct Ans-EN difference of 2 or more, makes ions with a full negative or positive charge (complete electron transfer) electrostatic potenial maps - Correct Ans-shows the charge distribution using colored clouds: red indicated electron-rich (-) regions and blue indicates electron-poor regions (+) lone pairs - Correct Ans-pairs of valence electrons that are not involved in covalent bond formation valence electrons - Correct Ans-Electrons on the outermost energy level of an atom involved in chemical bonding number of valence electrons - Correct Ans-depends on the column in the periodic table (skips SC-ZN) H-bonds - Correct Ans-occurs between the lone pair of a very electronegative element and a hydrogen in another molecule Hydrogen bonding in water - Correct Ans-Each water molecule is attracted to another through hydrogen bonding. each water molecule can bond to 4 others. Hydrogen bonds in ice - Correct Ans-are more "ordered" than in liquid water, making ice less dense (pushes the molecules further apart) solvent - Correct Ans-A liquid substance capable of dissolving other substances solute - Correct Ans-A substance that is dissolved in a liquid What do non-polar solvents dissolve? - Correct Ans-non-polar or moderately polar solutes (like dissolves like) which type of molecule will dissolve in water? - Correct Ans-polar molecules what do polar solvents dissolve? - Correct Ans-polar or moderately polar solutes but NOT non-polar solutes (like dissolves like) how do molecules move at a higher temperature? - Correct Ans-faster (higher average kinetic energy) specific heat capacity - Correct Ans-the energy required to raise the temperature of one gram of a substance by one degree Celsius latent heat - Correct Ans-heat absorbed or radiated during a change of phase at a constant temperature and pressure gustation - Correct Ans-detects chemical species dissolved in solutions (taste) chemesthesis - Correct Ans-The ability to feel a food's chemical properties (e.g., cool mints or hot chili peppers). covalent bonding rule - HONC - Correct Ans-H = 1, O = 2, N = 3, C = 4 double bonds - Correct Ans-two single covalent bonds that occur between the same two atoms formal charge - Correct Ans-# of valence electrons - ( # dots + # lines) organic molecule skeletons - Correct Ans-carbon atoms are not shown but are implied at the intersection of lines and at the end heteroatoms - Correct Ans-Atoms in an organic compound other than carbon and hydrogen (hydrogen bonded to carbon are not shown, assume enough hydrogens are attached to the carbon to make 4 bonds) planar carbon centres - Correct An