Lesson 21
Which of the following is a correct comparison of metals and semi-conductors?
Metals' resistance increases when temperature increases while a semi-conductors resistance decreases.
When you compare the band gap for a red and a blue LED, what is true?
The red LED has the smallest band gap.
If GaAs forms a semiconductor like Ge, which of the following elements will form a semiconductor like Si?
Al and P
Which of the following is NOT why alloys are useful to us today? Alloys
have a higher conductivity rate but they are useful because they have lower melting temperatures, are less malleable and reduce weight in objects.
What happens to the number of MO's as the number of atoms that come together increases?
increases
Which type of atom has valence electron states high enough in energy that they overlap with the stacked together molecular orbitals that form the conduction band?
metal
Which type of atom has valence electrons higher in the energy well?
metal
Which type of atom has the highest ionization energy?
non-metal
Locate the elements palladium (Pd, atomic #46) and nickel (Ni, atomic #28) on the periodic table. If Pd is combined with Ni, which of the following characteristics will the product show at room temperature?
shiny, malleable solid
Why are metals opaque?
because metals have empty, overlapping orbitals for their electrons
What happens to the spacing between the energy of one MO and the next one immediately above or below it as the number of atoms that come together increases?
decreases
Current can flow in all directions in an LED.
false
Metals have higher ionization energies than non-metals do
false