Lectures: Test 1 Flashcards
What is chemistry?
Study of matter, its properties, and its composition.
What is matter and what are its states?
Stuff that occupies space: states are 1. Solids: have a definite shape 2. Liquids: atoms are close together but have no definite shape; also has a "top," or a surface. 3. Gases: atoms very spread apart [4. plasma: just ions everywhere]
What are physical properties?
Properties of a substance that do not concern interactions with other chemicals.
What are chemical properties?
Properties of a substance regarding its interaction with other chemicals.
What is the difference between a physical and a chemical change?
- Physical changes are reversible and do not alter the composition of the substance [such as state changes].
- Chemical changes are not [easily] reversible and do involve composition change [such as hydrolysis where H2O becomes H2 and O2
What is energy? PE? KE?
- PE: due to position of object
- KE: due to movement of object
- Total energy: PE + KE; is the ability to do work.
What is the relationship between energy state and stability?
Lower energy states are more stable and are preferable.
What are the 7 fundamental [SI] units?
mass: kilogram [kg]
length: meter [m]
time: seconds [s]
temperature: kelvin [K]
amount: mol
current: ampere [A]
luminous density: candle [cd]
Given magnitude and symbol for the following prefixes
- mega
- kilo
- centi
- milli
- micro
- nano
- M = 10^6
- k = 10^3
- c = 10^-2
- m = 10^-3
- μ = 10^-6
- n = 10^-9
What is one mL in SI units?
1 cm^3
A conversion factor is _____, and the factor label system is _____
- a ratio of equivalent quantities.
2. dimensional analysis: use of conversion factors to convert one unit to another.
Density is _____
mass / volume
How to convert from C to F to K?
- K = C + 273.15
2. F = 9/5 C + 32
What is the difference between intensive and extensive properties?
- Intensive properties don’t change with amount of substance.
- Extensive properties do change with amount.
Classify the following as intensive or extensive properties:
density, melting point, mass, energy, boiling point, color, volume.
- density is intensive
- melting point is intensive
- mass is extensive
- energy is extensive
- boiling point is intensive
- color is intensive
- volume is extensive
What is the difference between precision and accuracy?
- Precision means data is close together
2. Accuracy means data is close to accepted value.
What are random errors vs. systematic errors?
- Random refers to low precision, low accuracy.
2. Systematic refers to high precision, low accuracy.
One angstrom is _____
10^-10 m
What is an element?
pure substances: only one kind of atom.
What are the seven diatomics?
H2, O2, N2, F2, Cl2, Br2, I2
What are compounds?
chemical combinations of 2 or more elements with chemical bonds. Can only be separated with chemical reactions.
What are mixtures?
combination of elements without chemical bonds. They retain the properties of individual components and you can separate them physically.
The law of conservation of mass says _____
mass is never created or destroyed. During chemical reactions, no mass is lost.
The law of definite composition says _____
any compound is composed of the same elements in the same parts [fractions] by mass.
The law of multiple proportions says _____
elements A and B react to form two compounds. The different masses of A and B can be expressed as a ratio of small whole numbers
What did John Dalton do?
Made the atomic theory.
What are the postulates of the atomic theory?
- All matter is atoms: indivisible units.
- Atoms of one element cannot be converted to another (through chemical reactions).
- Atoms of one element are identical to every other in mass and other properties.
- Compounds result from chemical combinations of a specific ratio of atoms of different elements. (per law of definite composition).
What did JJ Thompson do?
- Developed plum-pudding model.
2. Measured ratio of mass of cathode ray particles to the charge.
What are cathode rays?
string of negatively charged particles determined to go from a negatively charged plate to a positively charged one.
What did Robert Millikan do?
Measured charge of electron with his “oil-drop” experiment. Found electrons have a negligible mass.
What did Ernest Rutherford do?
Tested the plum-pudding model with the gold-foil experiment. Determined that atoms have positively charged particles in a “nucleus.”
What did James Chadwick do?
discovered the neutron; measured the mass of protons; neutron have the same mass as protons.
Atomic symbol of an element refers to _____
The letter or combination of letters signifying one particular element.
The atomic number refers to _____
the umber of protons in the nucleus of an element.
Number of electrons in an atom may be determined from the _____ number
atomic
What is required to determine the number of neutrons in the nucleus of an atom?
The mass number and the atomic number
The mass number is ____
The number of neutrons plus the number of protons in the nucleus of an atom.
Two atoms are isotopes when _____
they have the same atomic number but different mass numbers; aka they have different numbers of neutrons in their nuclei.
The percent abundance of isotopes is determined via _____
mass spectrometry
Avg. atomic mass is determined by the following equation: _____
avg atomic mass = Σ (isotope mass) x (% abundance / 100)
The main group elements consist of _____
On the periodic table, groups 1, 2, and 13-18
The transition elements consist of _____
groups 3-12 on the periodic table.
The alkali metals are group _____ and consist of elements _____. Their common property is that they are _____
- 1
- Lithium, sodium, potassium, rubidium, caesium, and francium
- Extremely reactive.
The alkaline earth metals are group _____ and consist of elements _____.
- 2
2. Beryllium, magnesium, calcium, strontium, barium, and radium.
The metalloids are elements _____
boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), astatine (At).
Elements to the right of the metalloids on the periodic table are _____, while those the left are _____
- Nonmetals
2. Metals
The noble gases are group _____ and consist of elements _____
- 18
2. the inert gases: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radeon (Rn)
The halogens are the group _____ and consist of elements _____
- 17
2. reactive nonmetals: fluorine (F), chlorine (Cl), bromine (Br), and iodine (I)
What are valence electrons?
Those on the outermost shell / orbital of the atom
What are compounds?
Two or more different elements in a chemical bond: only valence electrons are relevant for chemical bonds.
An ionic bond occurs when _____
A metal atom gives up an electron (making it an anion) to a nonmetal (making it a cation) so the two [almost] complete their outermost electron shells. The two ions are then forced together via electromagnetic attraction.
Covalent bonds occur when _____
Electrons are shared between two nonmetals: both atoms want more electrons so neither gives its electrons up. Instead, they share.
Covalent bonds occur between two ______.
Nonmetals
What is a monatomic ion?
One atom; an ion that is one atom.
What is a polyatomic ion?
An ion consisting of two or more atoms: like CO^2-, _3
List the common positively charged monatomic ions, the formulas and names.
Cations: H+ hydrogen Li+ lithium Na+ sodium K+ potassium Cs+ cesium Ag+ silver Mg(2+) magnesium Ca(2+) calcium Sr(2+) strontium Ba(2+) barium Zn(2+) zinc Cd(2+) cadmium Al(3+) aluminum
List the common negatively charged monatomic ions, the formulas and names.
Anions: H- hydride F- fluoride Cl- chloride Br- bromide I- iodide O(2-) oxide S(2-) sulfide N(3-) nitride
List the common metals that form more than one monatomic ion; the formula, systematic name, and common name.
Cr(2+) chromium(II) chromous Cr(3+) chromium(III) chromic Co(2+) cobalt(II) N/A Co(3+) cobalt(III) N/A Cu(+) copper(I) cuprous Cu(2+) copper(II) cupric Fe(2+) iron(II) ferrous Fe(3+) iron(III) ferric Pb(2+) lead(II) N/A Pb(4+) lead(IV) N/A Hg_2 (2+) mercury(I) mercurous Hg(2+) mercury(II) mercuric Sn(2+) tin(II) stannous Sn(4+) tin(IV) stannic
List the common polyatomic ions.
NH_4(+) ammonium H_3O(+) hydronium CH_3COO(-) acetate CN(-) cyanide OH(-) hydroxide ClO(-) hypochlorite ClO_2(-) chlorite ClO_3(-) chlorate ClO_4(-) perchlorate NO_2(-) nitrite NO_3(-) nitrate MnO_4(-) permanganate CO_3(2-) carbonate HCO_3(-) hydrogen carbonate CrO_4(2-) chromate Cr_2O_7(2-) dichromate O_2(2-) peroxide PO_4(3-) phosphate HPO_4(2-) hydrogen phosphate H_2PO_4(-) dihydrogen phosphate SO_3(2-) sulfite SO_4(2-) sulfate HSO_4(-) hydrogen sulfate
What is molecular mass?
Sum of atomic masses
What is the rounding rule for calculating molecular mass
Never round
What is stoichiometry
Study of quantitative aspects of formulas and reactions
What is a mole?
1 mol = an amount of atoms = Avogadro’s number of atoms (or molecules) = 6.022x10^23
What is molar mass
g/mol = number under the atomic symbol on the periodic table
How to convert from mass to mol?
Divide given mass by the molar mass
How to convert from mol to # of molecules?
Multiply x mol by Avogadro’s number
How to convert from number of molecules to mols to mass?
Divide # of molecules by Avogadro’s number to get mols. Times by molar mass to get mass.
