ch 21 unit 3 physical science
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.
If a certain LED (doped semi-conductor) is cooled in liquid nitrogen, the color moves to a higher frequency. What happens to the band gap?
It increases in energy.
Which of the following is a correct comparison of metals and semi-conductors? Select one: a. Metals have a larger band gap than semi-conductors. b. Metals' resistance increases when temperature increases while a semi-conductors resistance decreases. c. Semi-conductors' molecular orbitals overlap while metals' don't. d. Metals have more valence electrons than semi-conductors. e. Metals have larger electrical resistance than semi-conductors.
b. Metals' resistance increases when temperature increases while a semi-conductors resistance decreases.
If GaAs forms a semiconductor like Ge, which of the following elements will form a semiconductor like Si?
Al and P
Compounds between two different metals are called
Alloys
Metals do not let light through.
true
Metals have a greater tendency than non-metals do lose electrons.
true
A metal is..
A network solid consisting of positively charged atoms in a sea of electrons
Why are alloys useful to us today?
a. have lower melting temperatures. c. are less malleable. d. reduce weight in objects.
Which of the following is NOT a characteristic of a metal or alloy? Select one: a. Electrically Conductive b. Thermally Conductive c. Malleable d. Brittle
d. brittle
Current can flow in all directions in an LED?
false
Metals have higher ionization energies than non-metals do.
false
The energies of the orbitals that form when metals interact are very widely spaced in energy.
false