final Flashcards
commonly used prefixes in metric system
prefix symbol meaning power of 10
mega M 1,000,000 10^6
kilo k 1000 10^3
deci d 0.1 10^-1
centi c 0.01 10^-2
milli m 0.001 10^-3
micro μ 0.000001 10^-6
nano n 0.000000001 10^-9
rules for sig figs
1) all nonzero integers ALWAYS count for significance ex: 3456 has 4 sig figs
2) zeros (3 classes of zeros)
a) leading zeros:NEVER count as sig figs
ex: 0.048 has 2 sig figs
b) captive zeros: ALWAYS count as sig figs ex: 16.07 has 4 sig figs
c) trailing zeros: only significant when # HAS A DECIMAL POINT
ex: 9.300 has 4 sig figs; 0.004020 has 4 sig figs; 150 has 2 sig figs
sig figs for x and ÷
the # of sig figs for answer is LEAST amount of sig figs u have in the problem
ex: 1.342 x 5.5 = 7.4
* when solving many calculations for 1 problem, don’t convert sig figs until LAST STEP
sig figs for + and -
only count decimal places
ex: 23.445 + 7.83 = 31.275 = 31.28
ex: 101 + 1.0 = 102
- always solve from left to right
density
density =mass/volume or D=m/V
- mass of substance per unit volume of substance
- common units: g/mL or g/cm^3
- when mass increases, density increases (directly proportional)
- when mass is constant and volume decreases, density increases (inversely proportional)
physical properties
- characteristic that are directly observable and unique to a substance
- ex: odor, volume, color, state (s,l,g,p), density, boiling pt, melting pt
chemical properties
- a substance’s ability to make new substances
- characteristics that determine how the composition of matter changes as a result of contact w/ other matter/influence of e
- characteristics that describe behavior of matter
- ex: flammability, rusting of steel, toxicity, enthalpy, chemical stability, reactivity, digestion of food
ethyl alcohol at 78ºC boiling point is a __ property
physical
hardness of a rock is a __ property
physical
sugar fermenting to form ethyl alcohol is a __ property
chemical
physical change
- change in 1 or more properties of a substance and not in its chemical composition
- ex: boiling pt or freezing water
- 3 states of water: in all phases, water mols are still intact; motion of mols and distance between them change
chemical change
- given substance becomes a new substance w/ diff properties and diff composition
- ex: Bunsen burner, methane reacts w/O2 to make CO2 and H2O, baking a cake, bleaching teeth (rxn happening), digesting food
crushing salt is a __ change
physical
burning wood is a __ change
chemical
dissolving sugar in water is a __ change
physical
melting a popsicle is a __ change
physical
protons and neutrons have the same __
mass
why do diff atoms have diff chemical properties?
the chemistry of an atom arises from its e-
isotopes
diff # of neutrons
- atoms w/ the same # of protons but diff # of neutrons
- show almost identical chem. properties
- chemistry of an atom is due to its e-
- in nature, elements are usually found as a mixture of isotopes
isotope symbol
A X Z X= the chemical symbol of element A= mass # (# of protons + # of neutrons) Z= atomic # (# of protons)
groups/families
elements in same VERTICAL columns and have similar chemical properties
periods
HORIZONTAL rows of elements
metals
LEFT of staircase
-most elements are these
non-metals
RIGHT of staircase
metalloids
ON the staircase
-have some metallic and some non-metallic properties
what are the metalloids?
Boring Silly Germs Are Ants Telling Politics Boron (B) Silicon (Si) Germanium (Ge) Arsenic (As) Antimony (Sb) Tellurium (Te) Polonium (Po)
what are the four physical properties of metals?
1) efficient conduction of heat and electricity
2) malleability (aluminum foil)
- they can be hammered into thin sheets
3) ductility
- they can be pulled into wires
- can be molded
4) lustrous appearance (shiny)
physical properties of non-metals
- lack properties of metals
- exhibit more variation in properties
- can be g, l, s @ room temp
physical properties of metalloids
exhibit a mixture of metallic and non-metallic properties
7 diatomic molecules
I Bring Clay For Our New Home
- Iodine (I2): lustrous, dark purple solid
- Bromine (Br2): reddish-brown liquid
- Chlorine (Cl2): pale green gas
- Fluorine (F2): pale yellow gas
- Oxygen (O2): pale blue gas
- Nitrogen (N2): colorless gas
- Hydrogen (H2): colorless gas
ions
- atom’s not neutral
- atom w a charge
- elements become ions
- imbalance of e-
- atoms can form ions by gaining/losing e-
cations
metals tend to LOSE 1 or more e- to form (+) ions
anions
non-metals tend to GAIN 1 or more e- to form (-) ions
-name changes to end in -ide
ion charges and the periodic table chart
Group or Family Charge
Alkali Metals (1A) 1+
Alkaline Earth Metals (2A) 2+
Halogens (7A) 1-
Noble Gasses (8A) 0
*group 1: +1 group 2: +2 group 3: +3 group 6: -2 group 7: -1 group 8: 0
what are the 3 steps of the scientific method?
1) make an observation
2) form a hypothesis
3) perform experiment
theory vs law
- theory: answers “why?”, leads to more questions
- the law: “this is what happened”, doesn’t lead to more questions
which of the 3 subatomic particles are the smallest?
electrons
__ contribute to the mass of an atom
protons
__ contribute to the size of an atom
electrons
__ dictates chemistry of an atom
electrons
naming compounds: binary compounds
- composed of 2 elements
- divided into broad classes
- compounds that contain a metal & non-metal (ionic)
- compounds that contain 2 non-metals (covalent)
nomenclature
naming
naming compounds: binary ionic compounds
- contains (+) cations and (-) anions
- type 1
- type 2
binary ionic compounds: type 1
-metal and non-metal
-compounds
-fixed charges
-metal present forms only 1 cation
consists of:
-alkali metals
-alkaline earth metals
-Al3+
-Ga3+
-In3+
-Zn2+
-Ag+
charges of transition metals
- Al3+
- Ga3+
- In3+
- Zn2+
- Ag+
binary ionic compounds: type 2
- metal and non-metal
- compounds
- no fixed charge
- need roman numerals (indicates charge of metal cation)
- charge of metal ion must be specified
- metal present can form 2 or more cations w diff charges
- consists of: transitional metals
naming type 1 binary ionic compounds
- cation is always named first (element name)
- anion named second (end in -ide)
examples of type 1 binary ionic compounds
NaCl: sodium chloride CaS: calcium sulfide Kl: potassium iodide SrI2: strontium iodide ZnS: zinc sulfide CaBr2: calcium bromide aluminum sulfide: Al2S3 Rb2O: rubidium oxide
naming type 2 binary ionic compounds
- cation always named 1st
- anion named 2nd (-ide)
- charge of cation is specified by roman numeral
examples of type 2 binary ionic compounds
CuBr: copper (I) bromide FeS: iron (II) sulfide PbO2: lead (IV) oxide MnI2: manganese (II) iodide CoCl3: cobalt (III) chloride CuI: copper (I) iodide tin (IV) bromide: SnBr4
name CrO2
chromium (IV) oxide
name chromium (II) fluoride
CrF2
what is the name of SrB2?
strontium bromide
what is the name of K2S?
potassium sulfide
what is the correct name of the compound that results from the most stable ion for sulfur & the metal ion that contains 24 e-?
iron (II) sulfide
binary compounds: type 3
- non-metal and non-metal
- greek prefixes to denote the # of atoms of each element
naming type 3 binary compounds
- 1st element named first & full element name is used
- 2nd element is named as though it were an anion
- prefixes are used to denote # of atoms present
- prefix mono- is never used for naming the 1st element
prefixes used to indicate numbers in chemical name
prefix number mono- 1 di- 2 tri- 3 tetra- 4 penta- 5 hexa- 6 hepta- 7 octa- 8 nona- 9* deca- 10*
examples of type 3 binary covalent compounds
CO2: carbon dioxide SF6: sulfur hexafluoride N2O4: dinitrogen tetroxide CO: carbon monoxide NO2: nitrogen dioxide selenium hexafluoride: SeF6 PCl5: phosphorus pentachloride dinitrogen monoxide: N2O
name SeO2
selenium dioxide
polyatomic ions
charged entities composed of several atoms bound together
- have special names
- *MUST MEMORIZE**
examples of polyatomic ions
NaOH: sodium hydroxide Mg(NO3)2: magnesium nitrate (NH4)2SO4: ammonium sulfate Fe3(PO4)2: iron (II) phosphate Ca(HCO3)2: calcium bicarbonate potassium permanganate: KMnO4 Fe(OH)2: iron (II) hydroxide antimony (III) oxide: Sb2O3
rules for naming acids
- if the anion DOESN’T HAVE an oxygen, the acid is named w/ the prefix hydro- and the suffix -ic attached to root of element name
- if anion DOES HAVE an oxygen, the acid name is formed from the root element name w/ the suffix -ic or -ous after it
- *ALL END IN “acid”**
- ate = -ic
- ite = -ous
examples of naming acids
HCl: hydrochloric acid HCN: hydrocyanic acid H2S: hydrosulfuric acid HF: hydrofluoric acid H3PO4: phosphoric acid H2S: hydrosulfuric acid nitric acid: HNO3 H2SO4: sulfuric acid HC2H3O2: acetic acid
names of some acids with O
ACID NAME HNO3 nitric acid HNO2 nitrous acid H2SO4 sulfuric acid H2SO3. sulfurous acid H3PO4 phosphoric acid HC2H3O2 acetic acid
names of acids without O
ACID NAME HF hydrofluoric acid HCl hydrochloric acid HBr hydrobromic acid HI hydroiodic acid HCN hydrocyanic acid H2S hydrosulfuric acid
NH4 +
ammonium
NO2 -
nitrite
NO3 -
nitrate
SO3 2-
sulfite
SO4 2-
sulfate
HSO4 -
hydrogen sulfate/bisulfate
OH -
hydroxide
CN -
cyanide
PO4 3-
phosphate
HPO4 2-
hydrogen phosphate
H2PO4 -
dihydrogen phosphate
CO3 2-
carbonate
HCO3 -
hydrogen carbonate/ bicarbonate
ClO -
hypochlorite
ClO2 -
chlorite
ClO3 -
chlorate
ClO4 -
perchlorate
C2H3O2 -
acetate
MnO4 -
permanganate
Cr2O7 2-
dichromate
O2 2-
peroxide
clues that a chemical rxn has occurred
1) the colors change
2) a solid forms
3) bubbles form
4) heat and/or a flame is produced, or heat is absorbed
balancing a chemical equation
- coefficients balance rxn
- sum of coefficients
- diatomic mols ∆ eq
1) atoms are neither created nor destroyed
2) can never ∆ subscripts in a complete rxn
3) reactants -> products
how to write + balance equations
- read description of chm rxn
- identify reactants, products, and their states
- write apprp formulas
- write unbalanced eq that summarizes the info from previous step
- balance the equation by inspection, starting w/ most complicated mol
- should finish w/ the same # of molecules on both sides of arrow
precipitate
the solid formed during a precipitation rxn
*exchange cations & anions
what are the 3 types of equations for rxns in aqueous solutions?
- molecular
- complete ionic
- net ionic
molecular equation
- shows complete formulas of all reactants and products
- doesn’t give a very clear picture of what actually occurs in solution
- consists of mols are a whole
complete ionic equation
- all substances that are strong electrolytes are represented as ions
- spectator ions
spectator ions
ions that don’t participate directly in a rxn in sol
* the ions that cancel out
net ionic equation
- includes only those components that are directly involved in the rxn
- spectator ions not included
- order doesn’t matter
- should always be balanced
Write the correct molecular equation, the complete ionic equation, and the net ionic equation for the reaction between cobalt(II) chloride and sodium hydroxide
molecular: CoCl2 (aq) + 2 NaOH (aq) -> Co(OH)2 (s) +2 NaCl (aq)
complete ionic: Co2+ (aq) + 2 Cl- (aq) + 2 Na+ (aq) + 2 OH- (aq) -> Co(OH)2 (s) + 2 Na+ (aq) + 2 Cl- (aq)
net ionic: Co2+ (aq) + 2 OH- (aq) -> Co(OH)2 (s)
what are the 7 strong acids?
1) H2SO4 = sulfuric acid
2) HCl = hydrochloric acid
3) HBr = hydrobromic acid
4) HI = hydroiodic acid
5) HNO3 = nitric acid
6) HClO4 = perchloric acid
7) HClO3 = chloric acid
strong acid
a strong electrolyte that produces H+ ions (protons) when it is dissolved in water
acids give __ to bases; bases accept __ and give __ to acids
H+; H+; OH-
is an acid and base is a good relationship?
yes
strong base
a substance that produces hydroxide ions (OH-) in water
what are the strong bases?
Group 1
Group 2
+
OH-
the net ionic equation for the rxn of a strong acid and a strong base is always the production of __
water
Avogadro’s number
6.022 x 10^23
molar mass
mass in grams of a substance
unit: g/mol
- coefficients don’t count, only subscripts
conversion trick
K H D b D C M king henry died by drinking chocolate milk km, hm, Dm, base unit (m, L, g), cm, mm kilo: 1000 hecto: 100 deca: 10 U: unit deci: 0.1 centi: 0.01 milli: 0.001 *micro: 0.000001 or 10^-6 *nano: 0.000000001 or 10^-9
mass percent of an element in a compound
mass of element present in 1 mole of compound / mass of 1 mole of compound
empirical formula
formula of a compound that expresses the smallest whole-number ratio of the atoms present
-simplest whole-number ratio
how to find the empirical formula
assume 100 g and change % to g
convert g to mol
divide by lowest number
round any decimals
molecular formula
the exact formula of the molecules present in a substance
(empirical formula)n
*n is an integer
*always bigger than empirical formula
how to find the molecular formula
- use the molar mass given and divide by the molar mass from ur new empirical formula
- use the number to multiply the empirical formula
do diatomics or sig figs matter in empirical/molecular formulas?
no
A gaseous compound containing carbon and hydrogen was analyzed and found to consist of 83.65% carbon by mass. Determine the empirical formula of the compound.
C3H7
A gaseous compound containing carbon and hydrogen was analyzed and found to consist of 83.65% carbon by mass. The molar mass of the compound is 86.2 g/mol. The empirical formula was determined to be C3H7. What is the molecular formula of the compound?
C6H14
molar mass of C3H7 = 43.086 g/mol
86.2 g/mol / 43.086 g/mol = 2
(C3H7) x 2 = C6H14
When 1.00 g of metallic chromium is heated with elemental chlorine gas, 3.045 g of a chromium chloride salt results. Calculate the empirical formula of the compound.
CrCl3
1.00g Cr
3.045 g CrCl
3.045 - 1.00 = 2.045 Cl
Cr 1.00/51.996 = 0.0192 / 0.0192 = 1
Cl 2.045/35.45 = 0.0577 / 0.0192 = 3
CrCl3
CrO4 2-
chromate
mole ratio
coefficient of unknown / coefficient of known
Consider the following balanced equation:Na2SiF6(s) + 4Na(s) → Si(s) + 6NaF(s)
How many moles of NaF will be produced if 3.50 moles of Na is reacted with excess Na2SiF6?
5.25 moles NaF
Propane, C3H8, is a common fuel used for heating in rural areas. Predict the number of moles of CO2 formed when 3.74 moles of propane is burned in excess oxygen.
oxygen.
C3H8+ 5O2→ 3CO2+ 4H2O
11.2 moles
steps for calculating the masses of reactants and products in chm rxns
- balance the eq for the rxn
- convert the masses of reactants/products to moles
- use balanced eq to set up appropriate mole
- use mole ratio(s) to calculate the # of moles of desired reactant or product
- convert moles back to mass
For the following unbalanced equation: Cr(s) + O2(g) → Cr2O3(s) How many grams of chromium(III) oxide can be produced from 15.0 g of solid chromium and excess oxygen?
21.9 g Cr2O3
limiting reactants
- determine which reactant is limiting to calculate the amnt of products tht will be formed
- methane and water will react to form products according to the eq: CH4 + H2O -> 3 H2 + CO
a) H2O molecules are used up first, leaving 2 unreacted CH4 molecules - amnt of products that can form is limited by the water
- water is limiting reactant
- methane is in excess
when solving for the amount of excess left over we must find out how much was __ - how much we __ __
needed; started with
percent yield
actual yield / theoretical yield x 100%
find the percent yield of a product if 1.50g of SO3 is made from 1.00g of O2 + excess sulfur
2 S + 3 O2 -> 2 SO3
89.8%
when solving the molar mass of diatomic molecules, always
x 2
energy
the ability to do work and produce heat
- needed to oppose natural attractive forces
law of conservation of energy
- energy can be converted from one form to another
- can neither be created nor destroyed
- total e content of the universe is constant
system
part of the universe on which we wish to focus attention
surroundings
include every this else in the universe
endothermic process
- heat flow is INTO a system
- ABSORBS e from surroundings
(+) q
exothermic process
- e flows OUT of the system
(-) q
energy gained by surroundings must be __ to the energy lost by the system
equal
feels warmer is (exothermic/endothermic)
exothermic
- giving off heat
feels colder is (exothermic/endothermic)
endothermic
- heat is trapped
is freezing water endothermic or exothermic?
exothermic