Chem midterm review

How many carbon atoms are contained in 2.8g of C2H4?

• 1.2 x 10^23

• 3.0 x 10^23

• 6.0 x 10^23

• 1.2 x 10^24

Consider atoms of the following elements. Assume that the atoms are in the ground state. The atom that contains exactly two unpaired electrons

• S

• Ca

• Ga

• Sb

The mass spectrum of the element Sb is most likely represented by which of the following?

• 
• 
• 
• 

Which of the following represents a pair of isotopes?

• A

• B

• C

• D

The mass spectrum of a sample of a pure element is shown below. Based on the data, the peak at 26 amu represents an isotope of which of the following elements?

• Al with 13 neutrons

• Mg with 14 neutrons

• Fe with 26 neutrons

• Ti with 26 neutrons

Which of the following ground-state electron configurations represents the atom that has the lowest first-ionization energy?

• 1s2 2s1

• 1s2 2s2 2p2

• 1s2 2s2 2p6

• 1s2 2s2 2p6 3s1

The photoelectron spectrum of the 1s electrons of two isoelectronic species, Ca2+ and Ar, are shown below. Which of the following correctly identifies the species associated with peak X and provides a valid justification?

• Ar, because it has completely filled energy levels.

• Ar, because its radius is smaller that the radius of Ca2+

• Ca2+, because its nuclear mass is greater than that of Ar

• Ca2+, because its nucleus has two more protons that the nucleus of Ar has