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CHEM
CHEM 120 EXAM 2 QUESTIONS WITH CORRECT
VERIFIED SOLUTIONS 100% GUARANTEED
PASS (2025/2026)
What is Molar Mass? - ANS ✓The atomic mass of any substance expressed in grams is the molar mass (MM) of that substance. Ex: Nitrogen Atom Molar Mass of N Atom --> 14.01 g Molar Mass of Diatomic N2--> 28.02 g Calculating Molar Mass - ANS ✓The molar mass of a substance is the sum of the molar masses of each element. Example: What is the molar mass of copper(II) nitrite, Cu(NO2 )2?
- The sum of the atomic masses is as follows: 63.55 + 2(14.01 + 16.00 + 16.00) = 63.55 + 2(46.01) = 155.57 amu Converting Moles to grams - ANS ✓multiply by molar mass 6.02 x 1023 particles = 1 mol = molar mass - If we want to convert particles to mass, we must first conver t particles to moles, and then we can convert moles to mass. Converting Between Grams and Moles - ANS ✓Example: Calculate the number of moles of carbon in 0.58-g diamond. GIVEN: 0.58 g C FIND: mol C SOLUTION MAP: g C --> Mol C
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1 mol/ 12.01 g Relations used: 12.01g C = 1mol C Solution: 0.58g C x 1 mol C/12.01 g C= 4.8x10^-2 Mol Carbon Converting Between Grams and Number of Atoms - ANS ✓How many aluminium atoms are in an aluminium can with a mass of 16.2 g? GIVEN: 16.2 g Al FIND: Al atoms SOLUTION MAP g Al --> Mol Al --> Number of Al Atoms Relationships used: 26.98 g Al = 1 mol of Al 6.022x10^23 = 1 mol (Avagadros Number) Solution: 16.2 g AL x 1 mol Al/26.98 g Al X 6.022x10^23 Al atoms/ 1 mol Al = 3.62x10^ Converting Between Number of Molecules and Mass of a Compound - ANS ✓What is the mass of 4.78 × 1024 NO2 molecules? GIVEN: 4.78 × 1024 NO2 molecules FIND: g NO2 SOLUTION MAP Solution Map: NO2 Molecules --> mol NO2 --> g NO Solution map 1 mol NO2/ 6.022 x10^23 NO2 molecules , 46.01 gNO2 / 1 mol NO Chemical Formulas as Conversion Factors - ANS ✓The subscripts in a formula show:
- The relationship of atoms in the formula
- The moles of each element in 1 mole of compound EX:Aspirin C9H8O 1 molecule: 9 atoms of C 8 atoms of H 4 atoms of O 1 mole: 9 moles of C 8 moles of H 4 moles of O
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Speed is what? - ANS ✓scalar quantity V= c/y C= 3.00x10^8 m/s Wavelength Versus Frequency - ANS ✓- The longer the wavelength of light, the lower the frequency.
- The shorter the wavelength of light, the higher the frequency. LONGER=LOWER SHORTER=HIGHER Our eyes can see what? - ANS ✓Our eyes can see the light in the visible spectrum is the range of wavelengths between 400 and 700 nm but not in ultra- violet or infrared spectrum. Radiant energy that has a wavelength lower than 400 nm and greater than 700 nm cannot be seen by the human eye. Raident Energy Spectrum - ANS ✓The complete radiant energy spectrum is an uninterrupted band, or continuous spectrum.
- The radiant energy spectrum includes many types of radiation, most of which are invisible to the human eye. Blue Light - ANS ✓shortest wavelength, highest frequency, high energy Red light - ANS ✓long wavelength, low frequency, low energy absorption - ANS ✓Electron gains potential energy and moves further away from the nucleus, a photon of light is absorbed. Emission - ANS ✓Electron loses potential energy and moves closer to nucleus, a photon of light is emitted. The Quantum Concept - ANS ✓The energy released from an object is not continuous rather that it is emitted in small bundles For example: A tennis ball that rolls down a ramp loses potential energy continuously . A tennis ball that rolls down a staircase loses potential energy in small bundles. The loss is quantized.
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Bohr on model of the atom - ANS ✓Niels Bohr speculated that electrons orbit about the nucleus in fixed energy levels. Electrons are found only in specific energy levels, and nowhere else. The electron energy levels are quantized. Electrons occupy sublevels within each level - ANS ✓These sublevels are given the designations s, p, d, and f. These designations are in reference to the sharp, principal, diffuse, and fine lines in emission spectra. The number of sublevels in each level is the same as the number of the main energy level The energy levels (Shells) and Sublevels (orbital) - ANS ✓The first energy level has one sublevel designated 1s. The second energy level has two sublevels designated 2s and 2p. The third energy level has three sublevels designated 3s, 3p, and 3d. What is an orbital - ANS ✓sthe region of space where there is a high probability of finding an atom. In the quantum mechanical atom, orbitals are arranged according to their size and shape. The higher the energy of an orbital, the larger its size shape of s orbital, how many orbitals? - ANS ✓shaped like a sphere, 1 orbital shape of p orbital - ANS ✓dumbbell/figure 8 Each of the p orbitals has the same shape, but each is oriented along a different axis in space shape of d orbital - ANS ✓Four leaf clover, 6 orbitals The MAX number of Electrons in Sublevels - ANS ✓The s sublevel holds a maximum of 2 electrons.
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First Ionization Energy - ANS ✓the amount of energy required to remove the first electron. Second Ionization Energy - ANS ✓the amount of energy required to remove the second electron. Metals ted to - ANS ✓loser electrons in chemcial reactions, while non-metals either gain or share them Metallic Character - ANS ✓of an element is a description of how much "like a metal" it is
- Metallic character can effectively be described as the opposite of ionization energy, so the trends in metallic character are the opposite of those for ionization energy
- Metallic character tends to increase down a group.
- Metallic character tends to decrease from left to right across a period. GOING DOWN INCREASES< LEGT TO RIGHT DECREASES END OF CH 9 - ANS ✓END OF CH 9 Where are core electrons located? - ANS ✓Found close to the nucleus Where are valence electrons located? - ANS ✓Found in the most distan s and p energy subshells What are Valence electrons responsible for? - ANS ✓They are responsible for holding two or more atoms together in a chemical bond. Octet Rule - ANS ✓the tendency for atoms to seek 8 electrons in their outer shells - Natural electron configuration of the Noble Gases **- Done by gaining, losing, or sharing electrons
- Increases stability** - H and He seek a "Duet"
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Ionic bonds - ANS ✓are formed when a metal cation is attracted to a nonmetal cation Covalent bonds - ANS ✓are formed when two nonmetals share valence electrons Ions - ANS ✓atoms that have a charge due to gain or loss of electrons
- Anion: ( - ) charged atom - Cation: (+) charged atom Ionic Bond - ANS ✓a bond formed through the transfer of one or more electrons from one atom or group of atoms to another atom or group of atoms Ionic Compounds - ANS ✓: compounds composed of oppositely charged ions that are held together by their attraction to each other
- Metal +Nonmetal
- Metal + Polyatomic Ion
- Polyatomic Ion + Non-metal
- Polyatomic Ion + Polyatomic Ion
- Net charge on compound equal to zero Covalent Compounds - ANS ✓: compounds composed of atoms bonded to each other through the sharing of electrons - Electrons NOT t ransferred - No + or - charges on atoms - Non - metal + Non-metal - Metalloid + non - metal - Also called "molecules" - Examples: **- H2O
- CO2 •** Cl - CH - SiO Central Atom - ANS ✓An atom in a molecule or polyatomic molecule that is bonded to two or more atoms Lewis Structure - ANS ✓shows the bonds between atoms and helps us visualize the arrangement of atoms in a molecule
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Tetrahedral Molecules - ANS ✓The four bonding pairs (and, therefore, atoms) are repelled to the four corners of a tetrahedron. Thus, the electron pair geometry is tetrahedral Trigonal Pyramidal Molecules - ANS ✓m is surrounded by three bonding pairs and one nonbonding pair.
- Thus, the electron pair geometry is tetrahedral and the molecular shape is trigonal pyramidal Bent Molecules - ANS ✓is surrounded by two nonbonding pairs and two bonding pairs. - Thus, the electron pair geometry is tetrahedral and the molecular shape is bent. Linear Molecules - ANS ✓the central C atom is bonded to each oxygen by two electron pairs (a double bond). - According to VSEPR theory, the electron pairs will repel each other and they will be at opposite sides of the C atom. - Thus, the electron pair geometry and the molecular shape are both linear. Trigonal Planar Molecules - ANS ✓is bonded to the oxygen by two electron pairs (a double bond) and to each hydrogen atom by one electron pair. - The electron pair geometry and the molecular shape are both trigonal planar Linear Molecule - ANS ✓Electron Geometry: Linear Molecular Geometry: Linear Angle: 180 Electron Groups: 2 Bonding Groups: 2 Lone pairs: 0 Trigonal Planar 1 - ANS ✓Electron Geometry: Trigonal Molecular Geometry: Trigonal Angle: 120 Electron Groups: 3 Bonding Groups: 3 Lone pair: 0
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Trigonal Planar 2 - ANS ✓Electron Geometry: Trigonal Planar Molecular Geometry: Bent Angle: 120 Electron Groups: 3 Bonding Groups: 2 Lone pair: 1 Tetrahedral 1 - ANS ✓Electron Geometry: Tetrahedral Molecular Geometry: Tetrahedral Angle: 109. Electron Groups: 4 Bonding Groups: 4 Lone pair: 0 Tetrahedral 2 - ANS ✓Electron Geometry: Tetrahedral Molecular Geometry: Trigonal Pyramidal Angle: 109. Electron Groups: 4 Bonding Groups: 3 Lone pair: 1 Tetrahedral 3 - ANS ✓Electron Geometry: Tetrahedral Molecular Geometry: Bent Angle: 109. Electron Groups: 4 Bonding Groups: 2 Lone pair: 2 Electronegativity - ANS ✓The measure of the ability of an atom to attract electrons to itself
**- Increases across period (left to right) and
- Decreases down group (top to bottom)** - fluorine is the most electrone gative element - francium is the least electronegative element Elements with HIGH electronegativity - ANS ✓have a strong pull on electrons Elements with a LOW electronegativity - ANS ✓have a WEAK pull on electrons
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The properties of compounds are generally not the same as the properties of the elements of which they are composed. EX: Glucose, NaCl Law of Constant Composition - ANS ✓Compounds always contain the same elements in a constant proportion by mass. What is a Chemical Formula? - ANS ✓an expression of the number of atoms of each element in a compound. Chemical formulas are the simplest method for representing chemical compounds
**- They tell you which atoms are included and, relatively, how many
- Examples** - - Sulfuric acid, H2 SO4 - Water, H2O How to List the Elements in Order in Compounds - ANS ✓C --> P --> N --> H --
S --> I --> Br --> Cl --> O --> O --> F Four Ways (Other ways of representing chemical compounds and elements) - ANS ✓-Molecular Formula
- Structural Formula
- Ball & Stick Formula
- Space - filling model Element and Compound Types - ANS ✓*Pure Substances * Elements Compounds Atomic / Molecular Molecular/Ionic Prefixes Used in Naming Molecular Compounds - ANS ✓ 1 - mono 2 - di 3 - tri 4 - tetra 5 - penta 6 - hexa 7 - hepta 8 - octa 9 - nona 10 - deca
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What are Molecular Compounds? - ANS ✓are compounds formed from two or more nonmetals. The basic units of molecular compounds are molecules composed of the constituent atoms. What are Ionic Compounds? - ANS ✓contain one or more cations paired with one or more anions. • In most cases, the cations are metals and the anions are nonmetals What is an Ion? - ANS ✓an atom or group of atoms with a charge. What is a Cation? - ANS ✓A positively charged ion What is a Anion? - ANS ✓A negatively charged ion What is a polyatomic anion? - ANS ✓A group of atoms bound together that has an overall charge Classifying Ions Chart - ANS ✓Ions (Cations) Monoatomic , Polyatomic (Anions) Monoatomic, Polyatomic Monoatomic Cations - ANS ✓Metal atoms can lose valence electrons and become positively charged cations Group 1A, 2A, 3A Transition Metals can form cations of multiple charges "ION" if a metal forms only one cations, it is named for the parent atom followed by the word and adds the suffix - ous or - ic. • The cation with the lower charge receives the - ous suffix; the one with the higher charge receives the - ic suffix. Ex; Fe2+, Fe3+ Exceptionions to the General Rules for Cation Charges - ANS ✓The transition elements below only form a single cation charge *•Exception = Zinc Zn2+
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What is an ionic compound composed of? - ANS ✓An ionic compound is composed of positive and negative ions What are binary compounds? - ANS ✓are those that contain only two different elements. The names for binary ionic compounds containing a metal that forms only one type of ion have the following form Rules to Writing Formula for Ionic Compounds - ANS ✓1. Write the symbol for the cation and its charge
- Write the symbol for the anion and its charge
- Charge (without sign) becomes subscript for the other ion
- Reduce subscripts to smallest whole-number ratio
- Check that the sum of the charges of the cation cancels the sum of the anions If the charges are not equal, total charge must equal zero. If you have more than one polyatomic ion, it is placed in parentheses. BECOMES 'IDE' Binary Ionic Compounds with Metal Whose Charge May Vary - ANS ✓Name of Cation (Metal) (Charge of cation (metal) in roman numerals in parentheses) base name of anion (nonmetal) + ide Ex: Fe (OH)2 --> Iron (II) Hydroxide Naming Binary Molecular Compounds - ANS ✓Rules to Naming Covalent Compounds
- Name first element in formula first 2. Name the second element in the formula with an −ide, as if it were an anion
- Use a prefix in front of each name to indicate the number of atoms
- Never use the prefix mono- on the first element
- The "o" and "a" endings of these prefixes commonly are dropped when they are attached to "oxide." Common Names to Memorize - ANS ✓•H2O = Water •NH3 = Ammonia •CH4 = Methane
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What are Acids? - ANS ✓are molecular compounds that form ions when dissolved in water. They are composed of hydrogen, usually written first in their formula, and one or more nonmetals, written second. We can categorize acids into what two groups? - ANS ✓Binary acids, those containing only hydrogen and a nonmetal Oxyacids those containing hydrogen, nonmetal, and oxygen Classifications of Acids - ANS ✓Acids (Formula has H as first element)
- Binary Contain only TWO elements
- Oxyacids Contain Oxygen Naming Binary Acids - ANS ✓Binary acids are composed of hydrogen and a nonmetal. Hydro + Base name of nonmental + ic + acid Example: • HCl(aq) is hydrochloric acid. Oxaycids - ANS ✓are acids that contain oxyanions—found in the table of polyatomic ions. Nomenclature Flowchart - ANS ✓Flowchart: Oxyacids (Contain Oxygen)
- "ite" Name of Oxaynion ends in - ite
- "ate" Name of Oxyanion ends in - ate The names of acids containing "ite" take this form: Base name of oxyanion + ous) + Acid Acids containing oxyanions ending with "ate" take this form: Base name of oxyanion + ic) + Acod Oxyanion Acryonom - ANS ✓sprITE is deliciOUS ATE too much feeling IChy
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In3+ (Type 1 Metal (M) Cations) - ANS ✓Indium Group 3= M3+ Zn2+ (Type 1 Metal (M) Cations) - ANS ✓Zinc Sc3+ (Type 1 Metal (M) Cations) - ANS ✓Scandium Ag+ (Type 1 Metal (M) Cations) - ANS ✓Silver H- (Type 1 Non-Metals (N) Anions) - ANS ✓Hydride F- (Type 1 Non-Metals (N) Anions) - ANS ✓Fluoride Group 7= Halogens N1- Cl- (Type 1 Non-Metals (N) Anions) - ANS ✓Chloride Group 7= Halogens N1- Br- (Type 1 Non-Metals (N) Anions) - ANS ✓Bromide Group 7= Halogens N1- I- (Type 1 Non-Metals (N) Anions) - ANS ✓Iodide Group 7= Halogens N1- O2- (Type 1 Non-Metals (N) Anions) - ANS ✓Oxide Group 6= N2- S2- (Type 1 Non-Metals (N) Anions) - ANS ✓Sulfide Group 6= N2- Se2- (Type 1 Non-Metals (N) Anions) - ANS ✓Selenide Group 6= N2- N3- (Type 1 Non-Metals (N) Anions) - ANS ✓Nitride Group 5= N3- P3- (Type 1 Non-Metals (N) Anions) - ANS ✓Phosphide Group 5= N3- Cr3+ (Cations, Systematic Name, Alertnante Name) - ANS ✓Chromium (III), Chromic
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Fe3+ (Cations, Systematic Name, Alertnante Name) - ANS ✓Iron (III), Ferric Fe2+ (Cations, Systematic Name, Alertnante Name) - ANS ✓IRon (II), Ferrous Cu2+ (Cations, Systematic Name, Alertnante Name) - ANS ✓Copper (III), Cupric CU+ (Cations, Systematic Name, Alertnante Name) - ANS ✓Copper (I), Cuprous Pb4+ (Cations, Systematic Name, Alertnante Name) - ANS ✓Lead (IV), Plumbic Pb2+ (Cations, Systematic Name, Alertnante Name) - ANS ✓Lead (II), Plumbous Au3+ (Cations, Systematic Name, Alertnante Name) - ANS ✓Gold (III), Auric Au+ (Cations, Systematic Name, Alertnante Name) - ANS ✓Gold (I), Aurous OH- (Poly Atomic Anions) - ANS ✓Hydoxide CN- (Poly Atomic Anions) - ANS ✓Cyanide OCN- (Poly Atomic Anions) - ANS ✓Cyanate SCN- (Poly Atomic Anions) - ANS ✓Thiocyanate MnO4- (Poly Atomic Anions) - ANS ✓Permangrante CO3-2 (Poly Atomic Anions) - ANS ✓Carbonate PO4-3 (Poly Atomic Anions) - ANS ✓Phosphate NO3- (Poly Atomic Anions) - ANS ✓Nitrate ClO3- (Poly Atomic Anions) - ANS ✓Chlorate BrO3- (Poly Atomic Anions) - ANS ✓Bromate
