Chem Test 1 Cheat Sheet - exam notes, problems, walkthroughs PDF

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Physical Properties 1.State of matter (solid, liquid, gas) 2.Boiling point 3.Freezing point 4.Solubility in other liquids 5.Malleability 6.Electrical Conductivity 7.Heat Conduction 8.Tensile Strength Chemical properties (& changes) involve changes in composition Physical properties (& changes) involve a constant composition Measurement comes in two types: 1.Qualitative–Did you make the right stuff? Aspirin isn’t insulin. 2.Quantitative- How much of something do I have (mass)? How big is it? UNITS UNITS UNITS Pure Units Mass - Kg Length - m Time - s Charge - C Derived Units Speed - m/s Volume - m3 Atomic number is the number of protons the atom has Isotopes have different mass numbers “neutrons” (think carbon 12,13,14) Written as a superscript with the mass number sometimes written as a subscript 12 C - top number is the mass number and the bottom is the atomic number 6 IONS Ion is an atom that has an unequal # of protons and electrons Cations = more positive Anions = more negative Written as a superscript in front of the symbol (C+2) The Periodic Table Metalloids are the border elements Alkalis are on the far left of the periodic table Alkali earth metals are to the direct right of the Alkalis Noble gases are on the far right Halogens are on the direct left of the noble gases Chalcogenides are to the direct left of the halogens Atomic number is a weighted average of all isotopes Natural abundance is the % occurence of that isotope Calculation : all % abundance / 100 (19.9924)(0.9048) + (20.9938)(0.0027) + (21.9914)(0.0295) = 20.180 amu 1. Take the atomic mass of the isotope 2. 3.

Multiply it by the % of abundance divided by 100 Add all of the isotopes x abundances together

Molecules A molecule is a combo of 2 or more atoms Diatomic molecules (H2, O2, N2, F2, Br2, Cl2, I2) Halogens Different atoms : MgO,  FeO, CO, NO, HCl Molecular mass “molar mass” is in g/mol Addtogether the atomic masses of the different atoms Like MgO is the AM for mg + the AM of O Amu = atomic mass unit Avogadro’s number = 1amu = 1.66053873x10 -27  kg

A mole is the # of atoms to turn an amu into a gram I mol = 6.02214150*1023 2Mg + O2→ 2 MgO: 1 atom of oxygen and 2 atoms of Mg make 2 molecules of mgO Energy and Stuff Distance between the two peaks is called the wavelength The number of times it goes up and down in a second (hour, minute, day) is called frequency and this is abbreviated v Combining these gives you a distance Wavelength (velocity) = c c = 3.00x10^8m/s is the speed of light in a vacuum You will get 1/s which is Hz Light is just another form of energy.. When light strikes matter, it can do 3 things 1. Reflects 2. Refracts 3. Goes straight through Absorbing light becomes a means of probing matter Different wavelengths of light interact with different things 1. Infrared light interacts with vibrations of bonds (Makes vibrations faster) 2. Microwave lights interact with rotations of bonds (Makes water rotate faster) 3. Visible or ultraviolet light interact with the electrons The bohr model and the photoelectric effect... Absorbing UV or visible light moves the electrons to a higher electron state Suppose I need 10^-18 J of energy to knock an electron off. This is called the work function of a material: the smallest amount of energy that will cause an electron to be emitted. It turns out that light energy is not additive in the way normal heat is. It comes prepackaged in single waves called “photons” E = hf E = h(c/wavelength) E = 6.626x10^34Js (3.00x10^8/600x10^-9m) Electrons won’t pair up unless they have to Paramagnetism - only atoms with unpaired electrons are attracted to magnetic fields Carbon 1 1 _____ 1s

1 1 _____ 2s

1 _____

1 _____ 2p

_____

Paramagnetic. Only until 2p has 4 electrons, it will not pair up. Core vs. Valence Electrons Core are the non-reactive ones Valence are the reactive ones Fe0 - 26e[Ar] 4s2, 3d6 Fe2+ - 24e[Ar] 4s0, 3d6 Fe3+ - 23e[Ar] 3d5 More orbital stuff 1.

No two electrons have the same 4 quantum numbers

2. Lowest energy levels fill up first 3. Electrons pair up as a last resort 4. An orbital being full or half full is good (lower in energy - d orbitals) l=0, s orbital (sphere) l=1 p orbital (dumbbell shape) l=2 d orbital (2 p orbitals together, x shape) l=3 f orbital l=4 g orbital n=1, l=0 is called 1s n=2, l=0 is called 2s n=2, l=1 is called 2p n=3, l=2 is called 3d 1s^2 means 2 electrons are in the 1s orbital 3d^7 means 7 electrons are in the 3d orbital...