Chemistry TCB Exam Flashcards
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Unlock answers| chemistry = |
| study of substances and the changes they undergo |
| Describe the Atlantic/Pacific rule. |
decimal Absent: start on the Atlantic side of the number, count the first non-zero number and all that follow decimal Present: start on Pacific side of the number, count the first non-zero number and count all that follow |
| How many sig figs do I use when measuring things in lab situations? (ex. graduated cylinder or ruler) |
| go to the nearest line given, then estimate one decimal past that (if a graduated cylinder shows lines every 1mL, your answer should be to the nearest 1/10mL ex. 10.5mL) |
| accuracy |
| how close a measurement is to the real answer |
| precision |
| how close a measurement is to other measurements |
How many sig figs in: 7.2340 0.03460 1,340.01 |
5 4 6 |
| How do we measure density? |
| mass/volume |
Put the following in scientific notation: 5,245,252 0.00346 |
5.25x10^6 3.46x10^-3 |
| If I shoot my bow, and I consistently hit low and to the left, are my shots precise or accurate or both? |
| precise (the shots are consistent, but not accurate, that is, they're not close to the bullseye) |
Convert the following: 1,288 inches = ____? meters 2.54cm / inch |
3,271.52cm or 3,270cm (3 sig figs) |
| independent variable |
| the thing I change/control |
| dependent variable(s) |
| the thing(s) you measure |
| law of conservation of energy |
| energy is neither created or destroyed |
| law of conservation of mass |
| mass is neither created or destroyed |
| law of conservation of matter |
| matter is neither created or destroyed |
Which can NOT be broken down any further? sodium, disulfate, diatomic oxygen, hydroxide |
| sodium, because its an element.; The rest are either molecules or compounds |
| Is a phase change a chemical change or a physical change? |
| Physical change because its only changing forms, not creating something new |
| chemical change |
| when a chemical reaction takes place and new products are formed |
| Which state of matter is typically the LEAST dense? |
| Gas |
| What is an alpha particle? |
| a helium nucleus (2 protons, 2 neutrons) |
| How do you balance nuclear equations? |
| balance the top number (mass number) and balance the bottom number (atomic number) |
| If the result of a nuclear equation is a particle with a mass number of 4 and atomic number of 2, what type of nuclear reaction happened? |
| alpha decay, because an alpha particle has an atomic # of 2 and mass # of 4. |
| If the result of a nuclear equation is a particle with a mass number of 0 and atomic number of -1, what type of nuclear reaction happened? |
| beta decay, because the result of beta decay is the decay of a neutron into a proton and the release of an electron |
Match the scientist: Bohr;;;;;;;;;;;;;;;;;; gold foil experiment JJ Thomson;;;;;;; planet model of atom Rutherford;;;;;;;; ; ; ; ; ; ;; plum pudding |
Bohr:; planetary model Thomson:; plum pudding Rutherford:; gold foil |
| What did the gold foil experiment done by Rutherford prove? |
| atoms have very tiny, but very dense nuclei |
| If I started with 48g of Carbon-12, and 1yr later I have 38g, what term describes what has happened? |
| radioactive decay |
| If the half-life of carbon-12 is 5.73yrs, and I started with 100g, how much is left after 11.46yrs? |
25 grams because 11.46yrs is 2 half-lives 100g-->50g-->25g |
| How many half-lives does it take to have 1/16 of the original sample left? |
4 half-lives 1-->1/2-->1/4-->1/8-->1/16 |
| If the mass number of element X is 48, and it has 22 protons, how many neutrons does it have? |
26 neutrons 48 - 22 = 26 |
| If the atomic number of element X is 43 and it contains 41 electrons, what is the ion charge? |
+2
|
What does the neutron do for an atom?
|
Three important things: 1. it supplies the force that holds the nucleus together 2. it makes the atom more stable 3. it is the "glue" of the nucleus |
What is the atomic mass of element X: isotope 1: 18.32amu, abundance 21.30% isotope 2: 19.27amu, abundance 70.20% isotope 3: 20.11amu, abundance 8.50% |
19.14amu 18.32 x .2130 = 3.90 19.27 x .7020 = 13.53 20.11 x .0850 = 1.71 |
| electrons have several energy levels, which contain _____, which contain _______ that each hold a pair of electrons. |
sublevels orbitals |
| s, p, d and f describe what? |
| electron sublevels (and areas on the periodic table that contain those sublevels) |
| What is the shape of the s-sublevel? |
| sphere |
| What is the shape of the p-sublevel? |
| dumb bell shape |
How many valence electrons do the following have? Na, C, Ne |
Na = 1 C = 6 Ne = 8 |
| What element has the same electron configuration as Al+3? |
Neon because aluminum lost 3 electrons, giving it the same configuration as the element with 3 less electrons |
| If we vaporize an element in a flame, what type of light is given off? |
| only specific wavelengths of light, which are based on the energy given off by the electrons as they fall back to their "ground state" |
| What color of light has the highest energy? lowest? |
highest: violet lowest: red |
| What is the electron configuration for Fe (iron)? |
| 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d8 |
| Why are valence electrons important? |
| they are the electrons involved in reactions and bonding |
| What halogen has the highest ionization energy? Why? |
| Fluorine because its outermost electron is closest to the nucleus |
| ionization energy |
| energy needed to "pluck" an electron from an atom; increases as you go right and up on the periodic table |
| Ionization energy is similar to what other trend on the periodic table? |
| electron affinity |
| atomic radius |
| measure of the size of an atom; it increases down a group, but decreases across a period |
| Why does atomic radius decrease across a period? |
| because as electrons and protons are added, the attraction between the nucleus and electrons increases, making the atom more "condensed" |
| When an atom gains electrons, it |
gets larger becomes an ion has a negative charge |
| Metals typically form ___ ions and are found on the ___ of the periodic table. Non-metals typically form ___ ions and are found on the ___ of the periodic table. |
positive, left negative, right |
| What is the difference between ionization energy and electron affinity? |
ionization energy= energy required to "pluck" an electron from the atom electron affinity= energy given off when an electron is gained |
| Which "block" contains the alkali metals and alkaline earth metals? |
| s-block |
| Which "block" contains the non-metals? |
| p-block |
| Which "block" contains the transition metals? |
| d-block |
| What makes transition metals unique? |
They are: good conductors of heat/electricity shiny, malleable, ductile |
| What makes alkali metals and alkaline earth metals unique? |
| they are highly reactive, soft metals |
| What makes the halogens unique? |
| they are highly reactive non-metals |
| Air is a mixture of gases including oxygen, nitrogen, helium, hydrogen and traces of other gases. Which gas makes up most (70+%) of earth's air? |
| nitrogen |
| Which "block" on the periodic table is the only one that contains both metals and non-metals? |
| p-block |
What is the formula for the following: sulfate sulfide ammonia ammonium |
SO4-2 S-2 NH3 NH4+1 |
| When atoms lose or gain electrons, they are trying to form stable electron configurations similar to which family? |
| noble gases |
Name the compound: NaNO3 SBr3 CaF2 KCl * 5H2O |
sodium nitrate sulfur tribromide calcium fluoride potassium chloride pentahydrate |
| When is the prefix "mono" used in naming compounds? |
| only on the second word of a covalent compound, never on the first. |
What does the Roman numeral next to a transition metal tell you? ex. copper (II) sulfate |
| it tells you the ion charge (positive) on the transition metal |
What does an acid have in its formula? What does a base have in its formula? |
H+ ion OH- ion |
| Which is the stronger covalent bond, a single bond or double bond or triple bond? |
| triple is strongest, then double, then single |
| Which covalent bonds are the longest, single, double or triple bonds? |
| single bonds are longest, then double, then triple |
| How many single covalent bonds can one carbon atom have? |
| 4 |
| alkane |
single chain hydrocarbon with the formula CnH*2n +2 ex. C8H18 |
| What does "Max eats peanut butter" refer to? |
naming alkanes and alcohols Max = methane/methanol eats = ethane/ethanol peanut = propane/propanol butter = butane/butanol |
| allotrope |
| a pure substance with different structural forms |
| What are the three most common allotropes of carbon? |
graphite diamond buckminster fullerine (buckyball) |
| alcohol |
a hydrocarbon in which a hydroxide (OH) has replaced CH3 on one side of an alkane ex. ethane = CH3CH2CH3 ethanol = CH3CH2OH |
| What are alcohols most used for? |
| they are burned for fuel |
| alloy |
| a mixture containing metals produced by melting them together |
Which of the following is NOT an alloy? steel bronze silver brass |
| silver, it is an element |
| molarity |
moles per liter mol/L |
| molality |
moles per kilogram mol/kg |
| What formula do we use to calculate Molarity? |
| Molarity = # mols / molar mass |
| In words, what is molarity? |
| concentration of a substance in a liquid (usually water) |
| How do we figure out the number of mols of a substance? |
| # mols = grams of substance / molar mass |
| How do we figure out molar mass? |
1. Look up each element's mass 2. Multiply by the # of atoms of that element 3. Add all the numbers together |
| What is Avogadro's Number? |
6.02 X 10^23 or 1 mole |
| How do we calculate the number of particles of a substance? |
| # particles = (# mols ) X (6.02 X 10^23) |
What type of reaction is shown below?
2HgO ---> 2Hg + O2 |
| decomposition reaction |
What type of reaction is shown below?
2Mg + O2 ---> 2MgO |
combination reaction OR synthesis reaction |
What type of reaction is shown below:
2K + 2H2O ---> 2KOH + H2 |
| single replacement reaction |
What type of reaction is shown below:
Br2 + 2NaI ---> 2NaBr + I2 |
| single replacement reaction |
| What must be true for a metal to replace another metal (or hydrogen) in a single replacement reaction? |
| it must be more reactive (from the activity series chart) than the one it replaces |
What type of reaction is shown below:
Na2S + Cd(NO3)2 ---> CdS + 2NaNO3 |
| double replacement reaction |
Balance this reaction:
NaCN + H2SO4 ---> HCN + Na2SO4 |
| 2NaCN + H2SO4 ---> 2HCN + Na2SO4 |
Balance this equation, give the type of reaction and name the compounds:
Ca(OH)2 + HCl ---> CaCl2 + H2O |
Ca(OH)2 + 2HCl ---> CaCl2 + 2H2O double replacement reaction calcium hydroxide + hydrogen chloride (hydrochloric acid) ---> calcium chloride + dihydrogen monoxide (water) |
What type of reaction is shown below, and name the compounds:
2C8H18 + 25O2 ---> 16CO2 + 18H2O |
combustion (burning) reaction
octane (gasoline) + diatomic oxygen (oxygen gas) ---> carbon dioxide + dihydrogen monoxide (water) |
| How many total electrons are involved in a double covalent bond? |
| 4 |
| polarity |
| describes if a molecule has a positive side and a negative side; like a magnet |
| How do we determine whether a molecule is polar or non-polar? |
check the electronegativity chart: a difference greater than 0.4 means polar...if the molecule is diatomic, it must be non-polar |
| electronegativity |
| a number given to elements to describe "how negative" or "how positive" they are |
Determine if the following is polar or non-polar: Na2S O2 TeCl2 Electronegativities: Na=0.9 S=2.5 O=3.5 Te=2.1 Cl=3.0 |
Na2S ---> polar (EN: 2.5-0.9=1.6) O2 ----> non-polar (diatomic) TeCl2 ----> polar (EN: 3.0-2.1=0.9) |
