CH 1 Lesson 2

Why is the atomic mass of nickel considered abnormal in the first transition series?

• Due to its high atomic number

• Due to the presence of five stable isotopes with an average mass of 58.7 u

• Due to its large atomic radius

• Due to its high melting point

Why is the atomic radius nearly constant from chromium (Cr) to copper (Cu) in the first transition series?

• Due to the decrease in nuclear charge

• Due to the increase in the number of 3d electrons causing repulsion

• Due to the decrease in the number of electrons

• Due to the decrease in atomic mass

Why are the elements of the first transition series used in making alloys?

• Due to their high melting points

• Due to their high densities

• Due to the relative constancy of their atomic radii

• Due to their metallic luster

Why do the elements of the first transition series have high melting and boiling points?

• Due to the weak metallic bonds

• Due to the large number of electrons forming strong metallic bonds

• Due to their large atomic size

• Due to their low atomic mass

Why is the magnetic moment of manganese (25Mn) larger than that of cobalt (27Co)?

• Because manganese has more paired electrons

• Because cobalt has more unpaired electrons

• Because manganese has 5 unpaired electrons in the 3d sublevel

• Because cobalt has a larger atomic radius

Why are transition metals considered ideal catalysts?

• They have high melting points.

• They have large atomic radii.

• They participate in the formation of bonds between reacting molecules and atoms on the surface of the metal.

• They are non-reactive.

Which of the following is used in the decomposition reaction of hydrogen peroxide?

• Divided Nickel

• Manganese dioxide

• Vanadium pentoxide

• Divided Iron

What is the activation energy of a catalyzed reaction if the difference between activation energy before and after using a catalyst is 30 kJ, and the total released energy is 80 kJ?

• 50 kJ

• 100 kJ

• 130 kJ

• 180 kJ

Why do most transition element ions appear colored?

• Due to the complete filling of the d sublevel.

• Due to the partial filling of the d sublevel.

• Because they absorb all photons of visible light.

• Because they reflect all photons of visible light.

Which of the following ions is colorless?

• Cr3+

• Cu2+

• Zn2+

• Fe2+