gchem 1 Flashcards
What does Z mean?
atomic number
What does A mean?
mass number
Why are anions larger than cations?
anions are bigger because they have gained electrons which repel each other and take up more space
metals are __ atoms with __ held electrons
larger, loosely
non-metals are __ atoms with __ held electrons
smaller, tightly
Why are larger atoms better at stabilizing charges?
form weaker pi binds because of decrease in overlapping p orbitals
What is the difference between electron affinity and electronegativity?
electronegativity - propensity of atom attracting an electron
electron affinity - amount of energy liberated when a molecule or neutral atom acquires an electron from outside
What is the first quantum number?
n - shell
what is the second quantum number?
l - subshell or orbital
What is the 3rd quantum number?
ml - orbital orientation , value from -L to L
What is the 4th quantum number?
Ms- spin (+ or -)
How many electrons in the s, p, d, f orbital?
2, 6, 10, 14
What are the Heisenberg Uncertainty and Pauli Exclusion principles?
Pauli Exclusion principle - no two electrons can all 4 quantum numbers the same
Heisenberg Uncertainty principle- more known ab electron position, the less we know about its momentum
What is the formula for the energy of a photon?
E = hf
h- planks constant
f- frequency
What is the formula for the energy of a photon?
E= hc/lambda
what is radioactive decay?
process by which unstable atoms change their chemical composition over time.
What is alpha decay?
loss of one He nucleus, which has a mass of 4 and atomic number of 2
What is beta decay?
neutron is changed into a proton - ejection of an electron
What is electron capture ?
proton is changed into neutron - via capture of electron
What is positron emission?
proton is changed into a neutron- expulsion of positron
What is gamma emission?
gamma rays are usually emitted as a byproduct of the types of decay outlined
What is half-life?
the amount of time required for exactly one-half of the mass of that substance to disappear due to radioactive decay
___ bonding orbitals are higher in energy than __ orbitals
anti, bonding
What’s the difference between covalent and ionic bonds?
covalent - 2 nonmetals are bonded (sharing of electrons)
ionic - metal and nonmetal (electrostatic attraction)
What makes a good electrolyte?
when compounds dissociate completely in water (ionic compounds are always good electrolytes)
Which two elements in the periodic table, if bonded, would create a bond with the maximum possible ionic character?
Francium fluoride
What is condosity?
molar concentration of a sodium chloride solution that has the same specific electrical conductance as the solution under test
What is bond length?
distance between nuclei of the atoms forming the bond
What is bond energy?
energy required to break a bond
Energy is ___ to break a bond, energy is __ when a bond is formed
required, released
What is the heat of combustion?
the amount of energy released when a molecule is combusted with oxygen
The higher the energy of a molecule (less stable), the __ the heat of combustion
higher
Why do bonds form?
form bonds when the resulting bond is a lower energy state
What is the difference between empirical and molecular formulas?
empirical - lowest possible number of moles that keep the original ratio in a chemical formula CH2O
molecular- the actual moles of each element C6H12O6
How do you calculate percent mass?
percent mass= mass of one element of the compound/total mass of compound x 100
how do you derive a chemical formula from percent mass?
- change percent mass of each element to grams
- convert the grams into moles by dividing by molar mass
- look at the element with lowest number of moles, divide into other molar amounts for each element to find ratio
What is the chemical formula for chlorate?
ClO3-
What is the chemical formula for nitrite and nitrate?
nitrite - NO2-
nitrate - NO3-
What is the chemical formula for chlorate and perchlorate?
chlorate - ClO3-
perchlorate - ClO4-
What is the chemical formula for hypochlorite?
ClO-
What is the chemical formula for carbonate and bicarbonate?
carbonate - CO3 2-
bicarbonate - HCO3-
What is the chemical formula for sulfate?
SO4 2-
What is the chemical formula for manganate?
MnO4 2-
What is the chemical formula for permanganate?
MnO4-
How do you name acids, where the ion ends in “ate”
“ic” nitrate turns into nitric acid
If an ion ends in “ite” the acid ends with __
“ous” nitrite -> nitrous acid
If there is a single ion, the acid is named with __ as the prefix and __ as the suffix
hydro, ic
iodide -> hydroiodic acid
What is the difference between atomic weight and molecular weight?
atomic - mass of one mole of any atom
molecular - sum of the masses of each element
How do you calculate the limiting reagent?
- have a balanced eq.
2. convert to moles to see which reactant is less
What is theoretical yield, actual yield and percent yield?
theoretical - amount of product in grams that would be produced if 100% completion
actual - experiment amount
percent yield - ratio of actual yield over theoretical yield x100
What are 2 ways to increase yield?
start with more reactants
shift equilibrium to right - (remove products as they are formed)
How to calculate how much oxygen is needed for combustion
add 1 for each carbon and subtract 0.5 for each oxygen. (this is a ranking system not the exact moles required)
Which requires the most oxygen to combust, propane, propanol or propanoic acid?
propane needs most, propanol, and propanoic acid needs most oxygen
What is equilibrium?
the state reached in the progress of a reversible reaction where there ceases to be additional NET progress in either forward or reverse direction
What is the formula for the law of mass action?
Keq= products/reactants
How does addition of a catalyst, increased temp, lowering activation energy, stabilizing the transition state, and addition of reactants/products affect equilibrium?
catalyst - no effect increase temp = exothermic rxn- increase Keq. lowering activation energy = no effect stabilizing transition state = no effect adding products/reactants = no effect
What is the reaction quotient?
calculation of products/reactants taken at any other point than equilibrium
If Q>K, the reaction will proceed to the __
left
If Q
right
What is le chatelier’s principle?
systems at equilibrium that experience change will shift left or right to reduce effects of that change and re-establish equilibrium
What is the difference between kinetics and thermodynamics?
kinetics - study of reaction rate (how fast reactants disappear)
thermodynamics - reflect the potential reactivity (enthalpy, free energy, entropy and Keq)
What 2 things must occur for a reaction to start?
- the reactants must collide with enough energy to overcome the energy of activation
- the reactants must be in the correct spatial orientation
How will increasing reactants, products, catalyst, energy of activation, energy of transition state, energy of reactants , and temperature affect rate of reaction?
inc. reactants = inc rate
inc. products = no effect
inc. catalyst = inc. rate
inc. energy of activation = dec. rate
inc. energy of transition state = dec. rate
inc. temp = inc. rate
the overall order of a reaction=
the sum of the exponents in the rate law
How do you calculate the order of each reactant using experimental data?
- find two trials where reactant in question changed
- note the factor by which reactant concentration changed
- note factor by which rate changed across those same 2 trials
- solve for Y in X^Y = Z.
X = factor which reactant changed
Y= order
Z= factor by which rate changed
