Chapters 1-4 Answers

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the idea that matter consists of _____ goes back to ancient Greek philosophers known as “atomists” (400 BC)
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small, indestructible particles
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_____ comes from the Greek word atomos meaning “indivisible”
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atom
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in what year did Cavendish prove that water is not an element?
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1766
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in what year did Lavoisier use chemical reactions performed in closed containers to develop the Law of Conservation of Mass
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1774
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when did Proust do the experiments that lead to the Law of Definite Proportions?
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1798-1804
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the combining mass ratio of the constituent elements is _____ for a given compound
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constant
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when did Dalton propose the Law of Multiple Proportions?
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1808
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if two elements can combine to form two different compounds, then the ratio between their combining mass ratios will consist of _____
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simple whole numbers
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4 parts to Dalton’s Atomic Theory
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1. all matter is composed of small, indestructible pieces called atoms
2. atoms of a given element have similar masses & proportions
3. atoms combine in simple, whole number ratios to make compounds
4. chemical reactions are a result of atom reshuffling
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1897: JJ Thomson discovered the electron & measures its _____ ratio
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charge to mass (q/m)
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Thomson proposes that atoms are made of electrons embedded in a sphere of _____ (a plum pudding)
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positive charge
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Robert Millikan measures the _____ of an electron, establishing that it is a very small, discrete part of an atom
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charge
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alpha particles
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particles with a positive charge
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2 results of Ernest Rutherford’s 1911 alpha particle experiments at a thin gold foil
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1. most alpha particles went through the gold foil
2. a very small fraction of them bounced back at the beam source
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Rutherford’s 4 conclusions from his alpha particle/gold foil experiments
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1. the atom has a small, dense, positively charged center called the nucleus
2. the nucleus makes up most of the mass of the atom
3. the electrons orbit the nucleus & are dispersed throughout the atomic volume
4. the atom is mostly empty space
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the _____ is an electrically neutral particle that is slightly more massive than a proton
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neutron
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isotopes
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atoms that have the same atomic number but different numbers of neutrons
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isotopes will have different ____
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mass numbers (A)
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atomic mass
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a weighted average of the mass of atoms in an element
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can calculate atomic mass with _____ & _____
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isotopic masses; fractional abundances
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molecules are formed from 2 or more nonmetal atoms that are _____ together
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chemically bonded
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molecular compounds contain molecules of 2 or more _____ atoms
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different nonmetal
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ion
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an atom or group of atoms that carry a net charge
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2 types of ions
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cations (positive charge) & anions (negative)
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3 naming rules for monatomic cations
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1. tend to be metals
2. usually given name of element
3. followed by a Roman numeral in ( ) if more than one cation is possible for element
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the number of _____ in a given sample can be counted using the mole
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representative units
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1 mole (mol) of any item contains _____ of the item
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Avogadro’s number (NA)
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many chemical reactions in general chemistry are carried out in _____ solution
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aqueous
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pure water can _____ if certain substances are dissolved in it
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conduct electricity
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substances that dissolve in water to make solutions that conduct electricity
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electrolytes
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_____ completely dissociate into ions when dissolved in water
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strong electrolytes
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_____ partially dissolve
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weak electrolytes
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_____ dissolve in water to give a solution that does not conduct electricity
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nonelectrolytes
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redox reactions involve the _____ of electrons
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transfer
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oxidation
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loss of electrons (charge increases)
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reduction
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gain of electrons (charge decreases)
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_____ contains an element which is reduced, which results in the oxidation of an element in another species
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oxidizing agent
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5 rules of oxidation numbers
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1. atoms in free elements have an oxidation number of zero
2. monatomic ions have an oxidation number equal to their charge
3. hydrogen atoms have an oxidation number of +1 in most compounds, except in metal hydrides, where it is -1
4. oxygen atoms have an oxidation # of -2 in most compounds except in peroxides where it is -1 & when combined with fluorine
5. fluorine atoms have an oxidation # of -1 in all compounds
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acids are proton (H+) _____
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donors
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bases are proton _____
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acceptors
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all acid base reactions are _____ reactions
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proton transfer
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Bronstead-Lowry theory helps explain how some weak bases produce _____ in aqueous solution
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OH-
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when a strong acid is added to a strong base the products are an ionic compound & water; classification?
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AAB
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when a _____ is added to a strong base the products are an ionic compound and water; BLAB
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weak acid
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when a _____ is added to ammonia (NH3) the product is an ammonium (NH4+) salt; BLAB
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strong or weak acid
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reactions between _____ salts & acids may result in gaseous products
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weakly basic
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reactions between sulfides & acids result in the _____ formation of hydrogen sulfide (H2S) gas
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direct
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bicarbonate
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HCO3-
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carbonates & bicarbonates react with acids to form _____ as a product
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carbonic acid (H2CO3)
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_____ is unstable aqueous solution & decomposes to form carbon dioxide (CO2) & water
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H2CO3
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bisulfite
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HSO3-
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sulfites & bisulfites react with acids to form _____ as a product
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sulfurous acid (H2SO3)
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_____ is unstable in aqueous solution & decomposes to form sulfur dioxide (SO2)& water
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H2SO3
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reactants: acid & sulfide
intermediate product: ?
gas evolved: H2S
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none
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reactants: acid & carbonate/bicarbonate
intermediate product: ?
gas evolved: CO2
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H2CO3
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reactants: acid & sulfite/bisulfite
intermediate product: ?
gas evolved: SO2
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H2SO3
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the most specific classification for acid-base reactions that result in gas evolution
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BLAB
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pure metals can displace _____ from water or acids & _____ from aqueous solutions containing metal ions
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hydrogen gas (H2); metals
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_____ “active” metals will displace less “active” metals
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more
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combustion reactions
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a redox reaction between any substance & oxygen
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oxygen undergoes _____ in combustion reactions
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reduction
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the combustion of organic compounds containing only carbon, hydrogen, & oxygen will always yield _____ & _____
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CO2 & H2O
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chemical reactions are a result of the _____ of atoms
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“re-shuffling”
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combination reaction
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A + B –> AB
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decomposition reaction
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AB –> A + B
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single displacement reaction
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A + BC –> AC + B
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double displacement reaction
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AB + CD –> AD + BC
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2 solubility rules
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soluble:
1. group 1A ions & NH4+
2. NO3- & C2H3O2-
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acid-base reactions involve changes in how electrons are _____ between atoms
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shared
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redox (oxidation-reduction) reactions involve the _____ of electrons between two atoms
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transfer
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molecular equation
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gives complete, neutral chemical formulas for each reactant & product but does not show how they exist in solution
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complete ionic equation
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shows how each reactant & product exists in solution
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all _____ are separated into ions
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strong electrolytes
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3 species not separated into ions
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1. solids, liquids, & gases
2. weak electrolytes
3. non-electrolytes
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net ionic equation
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shows the species that change during a chemical reaction
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spectator ions
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species that do not change during the course of a chemical reaction
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a precipitation reaction is the reaction between two solutions containing strong electrolytes to form a _____ product
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solid
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Arrhenius Acid-Base Theory
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acids are compounds that produce H+ ions when dissolved in water; H+ combines with water to form H3O+ ions in aqueous solution; bases are compounds that products OH- ions when dissolved in water
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6 strong acids
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1. HCl
2. HBr
3. HI
4. HNO3
5. HClO4
6. H2SO4
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6 strong bases (soluble metal hydroxides)
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1. LiOH
2. NaOH
3. KOH
4. Ca(OH)2
5. Sr(OH)2
6. Ba(OH)2
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Arrhenius Acid Base “Neutralization” Reactions
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when acids & bases are combined, they form an ionic compound & water; an ionic compound formed from an acid-base neutralization reaction is called a salt
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all strong acid-base neutralizations have the same _____
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net ionic equation
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electrolytes are compounds that produce _____ when dissolved in water
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ions
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ammonium
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NH4+
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acetate
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C2H2O2- (CH3COO-)
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hydroxide
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OH-
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nitrate
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NO3-
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carbonate
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CO3 2-
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sulfate
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SO4 2-
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phosphate
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PO4 3-
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ionic compounds are composed of cations & anions that are held together by _____
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electrostatic forces
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nonmetals tend to form monatomic _____
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anions
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monatomic anions are given a name that combines the beginning of the element name & the suffix _____
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“-ide”
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binary molecular compounds
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no metals! usually 2 nonmetals
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3 rules for naming binary molecular compounds
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1. each element receives a prefix which denotes how many times it appears in the chemical formula of the compound
2. if the first element appears once the prefix is not needed
3. the second element’s ending is replaced with “-ide”
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binary acids
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contain hydrogen & one other nonmetal
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3. rules for naming binary acids
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1. the prefix “hydro-” is given
2. the ending for the non-hydrogen element is replaced with “-ic”
3. the word “acid” is then appended to the name
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oxoacids contain hydrogen, _____, & at least one other element
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oxygen
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4 rules for naming oxoacids
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1. no prefixes are used for oxoacid naming
2. if the name of the polyatomic ion in the acid’s chemical formula ends in “-ate”, it is replaced with “-ic”
3. if the name of the polyatomic ion in the acid’s chemical formula ends in “it”, it is replaced with “-ous”
4. the word acid is still appended to the name
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molecular & formula mass
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the sum of the atomic masses for all atoms in a molecule of formula unit
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atoms, molecules, & formula units are extremely _____
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small
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_____ can be used to convert between grams & moles of a sample
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molar mass
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_____ can be used to convert between moles & number of particles in a sample
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Avogadro’s number
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solute
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the substance that is being dissolved
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solvent
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the substance that does the dissolving
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molarity
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moles of substance/liters of solution
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to dilute a solution means to decrease its concentration by adding more _____
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solvent
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mass %
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mass in compound/mass of compound
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the percent composition of organic compounds can be determined using _____
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combustion
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n
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molecular mass/empirical formula mass
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stoichiometry
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the study of the relationships among the quantities of reactants & products involved in chemical reactions
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limiting reactant
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the reactant that is completely used up when carrying out the reaction
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% yield
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actual yield/theoretical yield x 100%
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the theoretical yield is the amount of product that can be formed from the _____
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limiting reactant
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quantitative analysis
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determining the amount of a species present in a material
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gravimetric analysis
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converting the analyzed species into something that can be isolated & weighed
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volumetric analysis (titration)
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titrations are used to determine the amount of a substance (analyte) in a solution by completely reacting it with another substance (titrant) that has a known concentration
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the endpoint
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a point slightly after the equivalence point indicated by indicators
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chemistry
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relating the structure of materials to their properties & interactions
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matter
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anything that takes up space & has mass
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the mass of a substance
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the amount of matter it has
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Law of Conservation of Mass
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the total mass in a system remains constant during a physical or chemical change
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3 main states of matter
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1. solids (rigid, incompressible, & have a fixed volume/shape)
2. liquids (fluid, incompressible, & have a fixed volume but indefinite shape)
3. gases (fluid, compressible, & have neither a fixed volume nor shape)
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physical change
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a change in the form of a substance
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chemical changes
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changing one type of matter into a new type of matter
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pure substances
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cannot be broken down using a physical process
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elements
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cannot be broken down using chemical processes
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compounds
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two or more elements chemically combined in fixed proportions
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mixtures
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combinations of two or more substances in varying proportions that can be separated using physical changes
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heterogeneous mixtures
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do not have a uniform composition throughout
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homogeneous mixture
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solutions have a uniform composition throughout
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kilo (k)
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1,000
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centi (c)
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0.01
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milli (m)
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0.001
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nano (n)
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0.000000001
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temperature measures the _____ of a substance
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thermal energy (“hotness”)
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English temperature unit, freezing temp, body temp, & boiling temp
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Fahrenheit; 32; 98.6; 212
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metric temperature unit, freezing temp, body temp, & boiling temp
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Celsius; 0; 37; 100
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SI temperature unit, freezing temp, body temp, & boiling temp
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kelvin; 273; 310; 373
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Fahrenheit to Celsius conversion
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Tc = 5/9 (Tf-32)
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Celsius to Fahrenheit conversion
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Tf = (9/5 x Tc) + 32
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Celsius to kelvin conversions
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Tk = Tc + 273
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the _____ of a measurement is reflected by the number of significant figures it has
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precision
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density
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the ratio between the mass (m) & volume (v) of a substance; mass/volume

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