Substances: a material that is chemically the same
Mixtures: matter that can be separated into simpler materials by physical means Accuracy: the agreement of a set of measures with the true value
Precision: the agreement among repeated measurements of the same quantity (results that are similar to each other)
Number of significant figures: the number of digits from the first nonzero digit through the last reported digit
Atom: the smallest unit
Element: composed entirely of one atom
Compound: two or more different elements
Law of Conservation of Mass: atoms do not change mass or density when a chemical reaction occurs
Atomic Number (Z) is the number of protons in an element
Mass Number (A) is the sum of protons and neutrons
Cation: has a positive charge and forms when an atom loses one or more electron Anion: has a negative charge and forms when an atom gains one more electron Isotopic mass: the mass, in u, of a particular isotope of an element
Atomic mass: the weighted average mass of the naturally occurring isotopes of an element Molecular mass: the sum of all the atomic masses in a molecule
Group 1A cation and NH4+
Chlorides, Bromides, Iodides (Cl, Br, I) If you want to learn more check out How do you calculate turbine efficiency?
Except with! (Ag+, Hg22+, Pb2+)
Except with! (Sr2+, Hg22+, Pb2+, Ba2+) We also discuss several other topics like What are the main reason why sexed semen is important?
Except with! Group 1A cations and NH4+
Except with! Group 1A cations and NH4+
Except with! Group 1A cations and NH4+, Sr2+, and Ba2+
Rules for Assigning Oxidation Numbers (IMPORTANT)
∙ An atom in its elemental state has an oxygenic number of zero.
∙ The oxygenic number of monatomic ions is the charge of the ion.
∙ In combination with other elements, the oxidation number of F is 1, O is generally 2, H
is generally +1 with a nonmetal and 1 with a metal. Other halogens are generally 1. ∙ The sum of the oxidation numbers in any species must equal the charge of the species. We also discuss several other topics like What comes out of volcanoes?
Common Polyatomic Anions to Memorize
Carbonate CO32 Phosphate PO43 Hydroxide OH Nitrate NO3 Sulfate SO42 Nitrate No3 If you want to learn more check out How do you find the probability distribution?
Chlorate CO32 Sulfite SO42
3a 4a 5a
1a alkali metals: soft, reactive, metals 2a alkaline metals
7a halogens: reactive nonmetals
8a noble gases: the stable elements
Conversions and Formulas
1mL = 1 cm3
TF = Tc x (1.8°F/1.0°C) +32°F
TC = (TF 32°F) x (1.0°C/1.8°F)
TK = TC + 273.15
Density = Mass/Volume
Avogadro’s Number: 6.022 x 1023
Mass percentage = (mass of element/ mass of compound) * 100
~Calculate the mass, in grams, of Al(OH)3 (molar mass = 78) formed by the reaction of exactly 0.500 L of 0.100 M NaOH with excess Al(NO3)3 Don't forget about the age old question of What is the function of pericardium?
1) Write and balance equation
a. Al(NO3)3 (aq) + 3NaOH 3NaNO3(aq) + Al(OH)3(s)
2) Use M = mol/L to find moles/liters of what you are given
a. 0.100 M = (mol/0.500 L) Don't forget about the age old question of What happens when thyroid stimulating hormone is high?
= 0.0500 mol NaOH
3) Use the coefficients in the equation to convert from one compound to the other a. 0.500 mol NaOH (1mol Al(OH)3/3 mol NaOH) = 0.167 mol Al(OH)3 4) Convert moles to grams of desired compound
a. 0.167 mol Al(OH)3 (78.0 g Al(OH)3/ 1 mol Al(OH)3) = 1.30 g Al(OH)3
Which symbol listed below describes a particle with 15 protons, 16 neutrons, and 16 electrons?
A. B. C. D.
~What mass of O2 will react with 5.00 g of H2? (Based on the give balanced equation) 2H2 + O2 2H20
1) Start with mass given in the question and convert that to moles
a. 5.00 g H2 (1 mol H2/2.02 g H2) = 2.50 mol H2
2) Next use the balanced equation to convert to moles of O2 (use the coefficients in the
a. 2.50 mol H2 (1 mol O2/2 mol H2) = 1.25 mol O2
3) Now convert moles of O2 to mass (use periodic table to get mass of O2) a. 1.25 mol O2 (32.0 g O2/1 mol O2) = 40.0 g O2
~Predict the solubility of the following compounds:
~What are the oxidation numbers for P and O in PO43?
We know that P is +5 because we know that O is 2 and there are 4 of them so (2) x 4 = 8. P must be +5 in order to give a 3 charge overall.
~What are the oxidation numbers for K, S, and O in K2SO4?
Since we know that O is 2, we start there. We also know that K is +1 (from the rules). Since we have 2(4) = 8 for O and +1(2) = 2 for K, the S must be +6
Name the element: Na2S
a. sodium sulfate
b. sulfur iodide
c. sodium sulfide
d. sodium selenide
e. none of these
What is the formula of barium phosphate?
The formula mass of sodium sulfate is:
Na+ and SO42
2(Na) = 2 x 23
1 S = 32
4 O = 4 x 16
Total: 142 u
How many atoms are present in 0.35 mol of Na?
0.35 mol Na * (6.022 x 1023/ 1 mol Na)
= 2.1 x 1023 atoms Na
How many moles are present in 3.00 x 1021 molecules of C2H6? 3.00 x 1021 C2H6 * (1 / 6.022 x 1023)
= 4.98 x 10 3 mols C2H6
Name the Molecules
a. Xenon hexafluoride
a. Dinitrogen pentoxide 3. Fe (OH)3
a. Iron (III) Hydroxide 4. HNO2
a. Nitrous acid