CHEM 101 - Exam 1 Study Guide 2024.

chemistry - answer-the study of matter and the changes it undergoes scientific method - answer-a systematic approach to research qualitative data - answer-general observations quantitative data - answer-comprising of numbers obtained by measurement hypothesis - answer-a tentative explanation for a set of observations law - answer-a mathematical relationship that is consistently found to be true theory - answer-a general principle or body of principles that has been developed to explain a wide variety of phenomena (this is NOT a wild guess) two major goals of science - answer-prediction and control two "better" goals of science - answer-understanding and explanation four basic rules of good science - answer-1. results should be reproducible by others 2. detailed research results should be reviewable 3. conclusions should be reasonable and unbiased 4. "give credit when credit is due" physics - answer-chemistry in motion biology - answer-chemistry in a cell engineering - answer-chemistry in application matter - answer-anything that occupies volume and has mass matter is governed by... - answer-composition and energy mixture - answer-a combination of two or more substances in which the substances retain their distinct identities homogeneous mixture - answer-composition of the mixture is the same throughout heterogeneous mixture - answer-composition of the mixture is not uniform throughout mixture separation - answer-physical means can be used to separate a mixture into its pure components element - answer-a substance that cannot be separated into simpler substances by chemical means number of elements defined - answer-114 number of elements that naturally occur on earth - answer-82 number of elements been created by scientists - answer-32 compound - answer-a substance composed of atoms of two or more elements chemically united in fixed proportions compound separation - answer-compounds can only be separated into their pure components (elements) by chemical means physical property - answer-properties that can be observed and measured without changing the composition of the substance (color, density, conductivity, etc.) chemical property - answer-properties that are only observable during a chemical change (combustibility, food digestion...) extensive property - answer-a property that depends upon how much matter is being considered (mass, length, volume) intensive property - answer-a property that does not depend upon how much matter is being considered (density, temperature, color) physical change - answer-does not alter the composition or identity of a substance (ice melting, sugar dissolving in water) chemical change - answer-alters the composition or identity of the substance(s) involved (hydrogen burns in air to form water) energy - answer-the capacity to do work radiant energy - answer-energy that comes from the sun and is earth's primary energy source thermal energy - answer-the energy associated with the random motion of atoms and molecules chemical energy - answer-the energy stored within the bonds of chemical substances nuclear energy - answer-the energy stored within the collection of neutrons and protons in the atom potential energy - answer-the energy available by virtue of an object's position First Law of Thermodynamics (Law of Conservation of Energy) - answer-energy can be converted from one form to another, but cannot be created or destroyed two critical parts to every measurement - answer-number and unit two major parts of each SI unit - answer-base unit and prefix mass - answer-measures the quantity of matter weight - answer-the force that gravity exerts on an object SI unit of mass - answer-kilogram 1 kg = 2.2 lbs formula for weight - answer-c*mass - on earth, c = 1.0 - on moon, c ~ 0.1 volume - answer-SI derived unit for volume is cubic meter (m³) - 1mL = 1cm³ - 1L = 1000mL = 1000cm³ = 1dm³ density - answer-SI derived unit is kg/m³ formulas for density - answer-mass/volume = m/v = kg/m³ - 1g/cm³ = 1g/mL = 1000kg/m³ conversion of Celsius to Kelvin - answer-K = °C + 273.15 conversion of Celsius to Fahrenheit - answer-°F = (9/5) x °C + 32 freezing point - answer-273.15K = 0°C = 32°F boiling point - answer-373.15K = 100°C = 212°F pound to Newton ratio - answer-1lb = 4.45N number of atoms in 12 g of carbon - answer-6.022 x 10²³ Avogadro's Number - answer-6.022 x 10²³ mass of a single carbon atom in grams - answer-1.99 x 10⁻²³ scientific notation rules (addition/subtraction) - answer-1. write each quantity with the same exponent n 2. combine N₁ and N₂ 3. the exponent, n, remains the same scientific notation rules(multiplication) - answer-Multiplication 1. multiply N₁ and N₂ 2. add exponents n₁ and n₂ scientific notation rules(division) - answer-Division 1. divide N₁ and N₂ 2. subtract exponents n₁ and n₂ roles of sig figs - answer-1. don't talk about Sig Figs...Any digit that is not zero is significant 2. zeros between nonzero digits are significant 3. zeros to the left of the first nonzero digit are not significant 4. if a number is greater than 1, then all zeros to the right of the decimal point are significant 5. if a number is less than 1, then only the zeros that are at the end and in the middle of the number are significant sig fig rules (addition/subtraction) - answer-the answer cannot have more digits to the right of the decimal point than any of the original numbers sig fig rules (multiplication/division) - answer-the number of significant figures in the result is set by the original number that has the smallest number of significant figures accuracy - answer-how close a measurement is to the true value precision - answer-how close a set of measurements are to each other Dalton's Atomic Theory - answer-1. Elements are composed of extremely small particles called atoms. 2. All atoms of a given element are identical, having the same size, mass and chemical properties. The atoms of one element are different from the atoms of all other elements. 3. Compounds are composed of atoms of more than one element. In any compound, the ratio of the numbers of atoms of any two of the elements present is either an integer or a simple fraction. 4. A chemical reaction involves only the separation, combination, or rearrangement of atoms; it does not result in their creation or destruction. proved that both atoms and electrons exist - answer-Cathode Ray Tube experiment conclusion of the Rutherford Experiment - answer-1. atom's positive charge is concentrated in the nucleus 2. proton (p) has opposite (+) charge of electron (-) 3. mass of p is 1840 x mass of e⁻ (1.67 x 10⁻²⁴ g) atoms are made mostly of... - answer-air most important take away from the Rutherford Model of the atom... - answer-the atom is mostly empty space atomic radius - answer-~ 100 pm = 1 x 10⁻¹⁰ m nuclear radius - answer-~ 5 x 10⁻³ pm = 5 x 10⁻¹⁵ m mass of a proton - answer-1.67262 x 10⁻²⁴ ~ mass of a neutron ~1840 x mass e⁻ mass of a neutron - answer-1.67493 x 10⁻²⁴ ~ mass of a proton ~1840 x mass e⁻ mass of an electron - answer-9.10938 x 10⁻²⁸ atomic mass - answer-the mass of an atom in atomic mass units (amu) 1 atom ¹²C is equivalent to... - answer-12 amu 1 atom ¹H is equivalent to... - answer-1.008 amu 1 tin ¹⁶O is equivalent to... - answer-16.00 amu atomic number (Z) - answer-number of protons in nucleus mass number (A) - answer-number of protons + number of neutrons OR Z + number of neutrons isotopes - answer-atoms of the same element (X) with different numbers of neutrons in their nuclei average atomic mass - answer-the weighted average of all of the naturally occurring isotopes of the element mass spectrometry - answer-helps identify the amount and type of chemicals present in a sample by measuring the mass-to-charge ratio and abundance of gas-phase ions period - answer-the horizontal rows on the periodic table group/family - answer-the vertical columns on the periodic table Group 1 - answer-Alkali Metals Group 2 - answer-Alkaline Earth Metals Group 17 - answer-Halogens Group 18 - answer-Noble Gases molecule - answer-an aggregate of two or more atoms in a definite arrangement held together by chemical forces (i.e., H₂O, NH₃, etc.) diatomic molecule - answer-contains only two atoms (i.e., H₂, N₂, O₂, Br₂, HCl, CO, etc.) polyatomic molecule - answer-contains more than two atoms (i.e., O₃, N₂O, NH₃, etc.) molecular formula - answer-shows the exact number of atoms of each element in the smallest unit of a substance empirical formula - answer-the simplest whole-number ratio of the atoms in a substance ion - answer-is an atom, or group of atoms, that has a net positive or negative charge cation - answer-ion with a positive charge; if a neutral atom loses one or more electrons anion - answer-ion with a negative charge; if a neutral atom gains one or more electrons monatomic ion - answer-contains only one atom (i.e., Na⁺, Cl⁻, Ca²⁺, O²⁻, Al³⁺, N³⁻) polyatomic ion - answer-contains more than one atom (i.e., OH⁻, CN⁻, NH₄⁺, NO₃⁻) ionic compounds (salts) - answer-- consist of a combination of cations and anions - the formula is usually the same as the empirical formula - the sum of the charges on the cation(s) and anion(s) in each formula unit must equal zero - the most reactive metals (Li, Na, Mg, K, Ca, Rb, Sr, Cs, Ba, Al) and the most reactive nonmetals (N, O, S, F, Cl, Br, I) as well as polyatomic ions combine to form thesel things to remember about ionic comoounds - answer-- often a metal + nonmetal - anion (nonmetal), add "-ide" to element name transition metal ionic compounds - answer-indicate charge on metal with Roman numerals molecular compounds - answer-nonmetals or nonmetals + metalloids how to write the formula for molecular compounds - answer-1) element furthest to the left in a period and closest to the bottom of a group on periodic table is placed first in formula 2) if more than one compound can be formed from the same elements, use prefixes to indicate number of each kind of atom 3) last element name ends in -ide H₂O - answer-water (dihydrogen oxide) NH₃ - answer-ammonia (nitorgen trihydride) CH₄ - answer-methane (carbon tetrahydride) HI - answer-hydrogen iodide NF₃ - answer-nitrogen trifluoride SO₂ - answer-sulfur dioxide N₂Cl₄ - answer-dinitrogen tetrachloride NO₂ - answer-nitrogen dioxide N₂O - answer-dinitrogen monoxide SiCl₄ - answer-silicon tetrachloride P₄O₁₀ - answer-tetraphosphorus decoxide the Mole (mol) - answer-a unit to count numbers of particles; the amount of a substance that contains as many elementary entities as there are atoms in exactly 12.00 grams of ¹²C 1 mol - answer-6.0221415 x 10²³ molar mass - answer-the mass of 1 mole of [anything] in grams 1 mole ¹²C atoms - answer-6.022 x 10²³ atoms = 12.00 g for any element, atomic mass (amu) is equal to... - answer-molar mass (grams) molecular mass/molecular weight - answer-the sum of the atomic masses (in amu) in a molecule percent composition - answer-(n x molar mass of element / molar mass of compound) * 100% - n is the number of moles of the element in 1 mole of the compound chemical reaction - answer-process in which one or more substances is changed into one or more new substances chemical equation - answer-uses chemical symbols to show what happens during a chemical reaction how to balance chemical equations - answer-1. write the correct formula(s) for the reactants on the left side and the correct formula(s) for the product(s) on the right side of the equation. 2. change the numbers in front of the formulas (coefficients) to make the number of atoms of each element the same on both sides of the equation. Do not change the subscripts. 3. start by balancing those elements that appear in only one reactant and one product. 4. balance those elements that appear in two or more reactants or products. 5. check to make sure that you have the same number of each type of atom on both sides of the equation. solution - answer-a homogenous mixture of 2 or more substances solute - answer-the substance(s) present in the smaller amount(s) solvent - answer-the substance present in the larger amount equilbirum - answer-a state in which there are no observable changes as time goes by chemical equilbrium - answer-achieved when... 1) the rates of the forward and reverse reactions are equal and 2) the concentrations of the reactants and products remain constant electrolyte - answer-a substance that, when dissolved in water, results in a solution that can conduct electricity nonelectrolyte - answer-a substance that, when dissolved, results in a solution that does not conduct electricity reversible reaction - answer-the reaction can occur in both directions strong electrolyte - answer-electrolytes with 100% dissociation weak electrolyte - answer-electrolytes that are not completely dissociated precipitate - answer-insoluble solid that separates from solution solubility - answer-the maximum amount of solute that will dissolve in a given quantity of solvent at a specific temperature how to solve net ionic equations - answer-1. write the balanced molecular equation. 2. write the ionic equation showing the strong electrolytes completely dissociated into cations and anions. 3. cancel the spectator ions on both sides of the ionic equation. 4. check that charges and number of atoms are balanced in the net ionic equation. acid - answer-a chemical substance that neutralizes alkalis, dissolves some metals, and turns litmus red - have a sour taste - react with carbonates and bicarbonates to produce carbon dioxide gas - react with certain metals to produce hydrogen gas base - answer-the opposite of an acid; differ from acids in their potential for accepting rather than releasing hydrogen ions - have a bitter taste - feel slippery Arrhenius acid - answer-a substance that produces H⁺ (H₃O⁺) in water. Arrhenius base - answer-a substance that produces OH⁻ in water. Brønsted acid - answer-a proton donor; must contain at least one ionizable proton Brønsted base - answer-a proton acceptor monoprotic acid - answer-an acid that can donate only one proton hydrochloric acid - answer-HCl hydrobromic acid - answer-HBr Hydroiodic acid - answer-HI nitric acid - answer-HNO₃ sulfuric acid - answer-H₂SO₄ perchloric acid - answer-HClO₄ hydrofluoric acid - answer-HF nitrous acid - answer-HNO₂ phosphoric acid - answer-H₃PO₄ acetic acid - answer-HC₃COOH neutralization reaction - answer-acid + base → salt + water gas producing reaction - answer-acid + base → salt + water + CO₂ reduction-oxidation (redox) reactions - answer-reactions in which electrons are transferred oxidation number - answer-the charge the atom would have in a molecule (or an ionic compound) if electrons were completely transferred rules for redox reactions - answer-1. free elements (uncombined state) have an oxidation number of zero 2. in monatomic ions, the oxidation number is equal to the charge on the ion 3. the oxidation number of oxygen is usually -2. In H₂O₂ and O₂²⁻ it is -1 4. the oxidation number of hydrogen is +1 except when it is bonded to metals in binary compounds. In these cases, its oxidation number is -1. 5. Group IA metals are +1, IIA metals are +2 and fluorine is always -1 6. the sum of the oxidation numbers of all the atoms in a molecule or ion is equal to the charge on the molecule or ion 7. oxidation numbers do not have to be integers. The oxidation number of oxygen in the superoxide ion, O₂⁻, is -½ combination reaction - answer-A + B → C decomposition reaction - answer-C → A + B combustion reaction - answer-A + O₂ → B displacement reaction - answer-A + BC → AC + B disproportionation reaction - answer-the same element is simultaneously oxidized and reduced