Periodic trends
Which atom in the pair has a higher ionization energy: Nitrogen or Oxygen?
Nitrogen - Ionization energy increases from left to right on the periodic table
What determines the atomic number of an element?
The # of protons
If a gas occupies 50 liters at 100 kPa, what is the pressure if the volume is reduced to 40 liters?
P2=125 kPa : P1V1=P2V2 (100)(50)=P2(40)
Which factor will increase the rate law? A) Decrease in temperature, B) Increasing the concentration of the reactants, C) Decreasing the surface area, D) Removing a catalyst
B) Increasing the concentration of the reactants - Increasing the concentration leads to more particles in a given volume, leading to more effective collisions between molecules.
What is the bond angle of NH3?
<109.5 : It has a tetrahedral shape, but since it has a set of lone pairs, it pushes the three H molecules downwards making the angle less than 109.5
Which element has the highest electronegativity?
Fluorine - F attracts electrons more than any other element because of it's effective charge and small atomic radius.
How is the atomic number of an element determined?
Adding the number of protons and neutrons
A 375 mL sample of nitrogen at 1.2 atm is reduced to 125 mL at constant temperature, what is the new pressure?
P2=3.6 atm : P1V1=P2V2 (1.2)(375)=P2(125)
What is the rate law of 2A + B ---> C
Rate =k[A]2[B] : There are 2 A's and 1 B. The coefficients add to 3.
What is the bond angle of CO2 and why?
180 because it is linear with no lone pairs.
Rank the following atoms by increasing atomic radius: Aluminum, Oxygen, Carbon, Potassium
O, C, Al, K - Atomic radius gets larger as you move to the right and up the periodic table
If a neutral atom has 10 protons and 8 electrons, what is it's charge?
+2 - protons (+) and electrons (-) ---> -8+10 = 2
How many moles are in a 6.2 L container at 3.0 atm and 37 degrees C
n= .75 moles : PV=nRT 37degreesC+273=310K n=PV/RT (3.0)(6.2)/(.0821)(310)
If the reaction rate is proportionate to the concentration of a reactant, what is the reaction order?
First order - The rate is directly proportional to the concentration, meaning that if the concentration is doubled, the rate also doubles, making it 1st order.
What is the molecular geometry of a molecule with 3 bond pairs and 2 lone pairs?
T- shaped or trigonal pyramidal : It has 5 electron domains, giving it a trigonal bipyramidal shape.
What are group 17 elements called?
Halogens - the very reactive nonmetals (Fluorine, Chlorine, etc.)
Which of the following has a negative charge? Proton, Neutron, or Electron
Electron - Electrons are negatively charged, protons are positively charged, and neutrons are neutral with no charge
A gas occupies 420 mL at 210K, what is the volume at 250K?
V2=500 mL : V1/T1=V2/T2 420/210 = V2/250
How does a catalyst speed up a reaction?
By providing an alternate pathway with a lower activation energy
What is the molecular geometry of methane (CH4)?
Tetrahedral : It has four bond pairs and no lone pairs, making a symmetric shape.
Which atom has the largest atomic radius: Sodium or Aluminum?
Sodium - Although both are in the same period, atomic radius gets smaller as you move to the left
How many valence electrons does Sodium have?
1 - Na is in group 1 of the periodic table
A balloon has a volume of 6 L at 7 degrees C, what is the volume if the temperature is increased to 147 degrees C?
V2=9 Liters : 7+273+280K --> 147+273=420K V1/T1=V2/T2 6/280=V2/420
If the rate of a reaction increases by a factor of 4 when the concentration of reactant A is doubled, what is the order of the reaction with respect to A?
Second Order - You can solve for x using 2x=4 which means x=2.
What is the bond angle of BF3?
120 : It has 3 bond pairs and no lone pairs, making a trigonal planar shape.