Fundamentals Flashcards
What is an amp?
A unit of measurement for electricity
1 Mega = __________
10^6 (MegaBYTE)
What is the relationship between liters and cm?
1L = 1000cm^3 (both units of volume)
1m^3 = ?
1 m^3 = 1000L
1mL = ____ cm^3 = ___cc
1ml = 1 cm3 = 1 cc
Angstrom is equal to ?
1 A = 1.0 ^ -10 m
Why is the angstrom useful as a unit of measurement?
It the right range for atomic radius and bond length
What is the range for atomic radii and bond length in angstrom?
1 to 3 Angstrom
By how many orders of magnitude is a centimeter longer than an angstrom?
1 cm = 10^ -2 m 1 Angstrom = 1E-10 m the difference is 8 orders of magnitude or factor of 8.
What are the two common units of density?
kg/m3 or g/cm3
What is the conversion between kg/m3 to g/cm3?
kg/m3 to g/cm3 divide by 1000 (Going from Larger unit to smaller duh)
What is the conversion between g/cm3 to kg/m3?
multiply by 1000
What is the density of water (g/cm3)?
1g/cm3
What is the density of water (kg/m3)?
1000kg/m3
What is a molecular formula?
A molecular formula tells us the identity and the number of each atom in a molecule ex. H20
A molecule is composed of ________
A molecule is formed when two or more elements are chemically joined (they can be the same or different)
What makes a compound?
Compounds are a type of molecule. A molecule that contains at least two different elements.
Are all compounds molecules?
Yes all compounds are molecules.
Are all molecules compounds?
No because O2 or H2 are molecules but can’t be compounds.
What is an empirical formula?
Method to describes the Numerical Proportions of atoms by using the smallest whole number to describe the same ratio of the atoms as in the molecular formula.
What is a chemical formula?
Method of expressing the exact number of atoms in a molecule.
If we know the chemical formula and we use the atomic weights listed on the period table what can we automatically figure out about the molecule overall?
The formula weight.
What is formula weight?
The sum of the atomic weights of all the atoms in the molecule.
What is the unit for atomic weight(mass)?
atomic mass unit (amu)
One atomic unit has been established to be equal to?
1/12 of the mass (g) of an atom of Carbon-12.
Carbon has 6 proton and 6 neutron. In grams this is 12*1.66E-24 grams = 2.0E-23 grams
The masses listed on the period table are an average of?
the weight average of the atomic mass units (amu) of all the naturally occurring isotopes of each element based on their abundance.
What is molecular weight?
Molecular weight is commonly used to describe the atomic mass of a molecule (it is the same as formula weight)
When is molecular weight used vs formula weight?
Molecular weight is used for molecules while formula weight is used for ionic compounds.
What is the mole?
The mole is a unit that relates atomic mass unit to grams. It is based on the atomic mass unit.
1 mole is = ?
1 mole = 6.022 ^ 23 atoms, molecules, ions, photon, electrons
what is the number of carbon-12 atoms in a sample mass of 12 grams?
6.022^23
12 g of Carbon 12 =
1 mole of Carbon = 6.022E23 atoms= 12 amu
Molecule’s percent mass composition cab be determined using what two formulas?
Empirical and molecular formula
Quickly Determine the percent of Carbon in C4H4N2?
2(12)/( 2x12 + 2x1 + 14) = 24/40 = .6 = 60%
Determine the empirical formula for a compound that contains 70% Iron and 30 % Oxygen?
70% = 70 grams of Iron 30 % = 30 grams of Oxygen Convert the grams to moles: 70 grams/55.8 g per mole = 5/4 = 1.25 moles 30/16 = 15/8 Determine the ratio of Iron to Oxygen (5/4) moles/ (15/8) moles = 2/3
Ratio of Iron to Oxygen is 2:3
Fe 2 O 3
What is Molarity?
moles of solute/ liters of solution
What is mole fraction?
The mole fraction (S)= number of moles of substance S / total moles in the solution
When is mole fractions used?
When more than one solute is present in solution and is most commonly used when discussing the composition of a mixture of gases.
The mass of a proton
1.66x10-24g
The mass of a neutron
1.66x10-24g
1 amu = ____ grams
1.66E10-24g (mass of proton/neutron)
In a chemical equation the Law of Conservation of Mass states that what must be true about the chemical equation?
The number of atoms on the reactants must equal the number of atoms on the products because the amount of matter (mass) does not change in a chemical reaction.
In a chemical equation the stoichiometric coefficients provide what information ?
The stoichiometric coefficients tells us the ratios of moles or molecules involved in the chemical equation not the ratios of mass.
How do we assign oxidation states?
Based on who owns the electrons(not share that is formal charge) in the molecule which is determined base on the affinity of the atoms towards electrons.
What are the main rules for assigning oxidation states to atoms?
- The oxidation of any element in its standard state is 0
- Sum of the oxidation states of each atom in a molecule that is in its neutral state must sum up to 0.
- Group I atoms are assigned an oxidation state of + 1
- Group II atoms are assigned an oxidation state of +2
- Group VII has an oxidation state of -1.
- Hydrogen has an oxidation state of +1 when bonded to something more electronegative than carbon and - 1 when bonded to something less electronegative than carbon and 0 when bonded to Carbon.
- Oxygen usually -2 except in peroxides or other compounds where it is forced to only take one electron since such as H2O2 or Na2O2 (oxdiation state of -1)
It can also be found at an oxdiation state of 0 if element.
It can have an oxidation state of +2 when it is not the most electronegative atom such as F2O.
What is oxidation state of an element in its standard state?
- The oxidation of any element in its standard state is 0
Sum of the oxidation states of each atom in a neutral molecule must equal?
0
Group I and II atoms have what oxidation states (except for Hydrogen)
+1 (Group 1) and +2 (group 2)
Group VII atoms have what oxidation state?
They have an oxidation state of -1
Oxygen has what oxidation states?
- 2 generally except for
1. when found in peroxides or group 1 metals then it adopts -1 charge
2. when bound to atom more electronegative than it is (Flouride) then it picks up +2 charge.
what oxidation state does hydrogen have?
Hydrogen will pick up - 1 charge when bound to atoms less electronegative than Carbon and + 1 charge when bound to atoms more electronegative then Caron and charge of 0 when bound to Carbon.
What is the order of electronegativity of some important elements?
FONClBrISCH (pronounced fawn-cull-brish) with flouride most electronegative and H least
What is the oxidation state of Fe3O4?
In this example Oxygen has -2 (-8 total) and Iron has to be (+8/3). We can have fractional charges. Two atoms of iron will have +3 charge while one will have +2.
