Unit Conversions
Convert 3.45 km to meters (m).
3.45 x 10^3 m
Name the halogen located in Period 3.
Chlorine (Cl)
State the number of protons, neutrons, and electrons in 31P^3-
15 protons, 16 neutrons, 18 electrons
Identify the most abundant isotope of Argon (Ar, atomic weight 39.948 amu) among 36Ar, 38Ar, and 40Ar.
40Ar
Calculate the molar mass of Calcium Phosphate, Ca(PO4)2
310.18 g/mol
A box contains 2.5 gross of pencils (1 gross = 12 dozen). How many total pencils are in the box?
360 pencils
Which of these elements is a metalloid: Na, Fe, Ge, Br, or He?
Germanium (Ge)
Describe how a neutral sulfur atom forms a S^2- anion.
By acquiring two additional electrons.
Explain why the atomic weight of chlorine on the periodic table is 35.45 amu rather than a whole number.
Because it is a weighted average of all naturally occurring isotopes based on their natural percent abundance, not the mass of a single atom.
A sample of pure silicon contains 4.82 x 10^24 atoms. How many moles of silicon are in the sample?
8.01 mol Si
A rectangular block measures 2.0 cm times 3.0 cm times 4.0 cm and has a mass of 162 g. Calculate its density
6.8 x 10^3 kg/m^3
Identify the alkali metal with the smallest atomic number.
Lithium (Li)
Atom X (12p, 12n, 10e) and Atom Y (12p, 14n, 10e). How are X and Y related?
They are isotopes of the same element
Element Z has two natural isotopes: 63Z (62.93 amu, 69.17%) and 65Z (64.93 amu, 30.83%). Calculate the average atomic mass of Z.
63.55 amu
Find the mass in grams of 0.503 mol of calcium gluconate, C12H22CaO14. (Molar mass = 430.37 g/mol)
216 g
Convert a speed of 60.0 miles/hour into m/s (1 mi = 1.609 km).
26.8 m/s
Classify each as element, compound, or mixture: O2 gas, CO2 gas, and salt water.
Element, Compound, Homogeneous Mixture.
Which element is most likely to form a +2 cation: Na, Mg, Al, P, or Cl?
Magnesium (Mg)
An element has two main isotopes 100.0 amu and 102.0 amu. If the average atomic mass is 101.70 amu, which isotope is more abundant?
The 102.0 amu isotope
A 155 g sample of Ca3(PO4)2 (Molar mass = 310 g/mol) contains how many moles of Calcium (Ca) atoms?
1.50 mol Ca
Convert 2.70 g/cm^3 to kg/m^3
2.70 x 10^3 kg/m^3
Which element is the most metallic: N, P, As, or Bi?
Bismuth (Bi)
Differentiate between atomic number, mass number, and atomic mass.
Atomic Number: Number of protons in the nucleus (defines the element).
Mass Number: Total number of protons + neutrons in a specific isotope (always a whole number).
Atomic Mass: The weighted average mass of all naturally occurring isotopes of that element.
Bromine has two stable isotopes: 79Br (78.918 amu) and 81Br (80.916 amu). If the atomic weight is 79.904 amu, calculate the % abundance of each isotope.
79Br = 50.65%, 81Br = 49.35%
Calculate the mass of oxygen present in 2.05 g of sulfur dioxide (SO2).
1.02 g O