Ch 21 Bonding in Metals, alloys, and semiconductors
What happens to the number of MO's as the number of atoms that come together increases?
Increases
Electrons act like a lubricant between layers of nuclei
Malleability
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.
Which of the following Pair of atoms is likely to form and alloy? O and Ga, Sn and Pb, N and Cl
Sn and Pb
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
an electron that is not focused around any one nucleus
delocalized electrons
a difference between metals and semiconductors is caused by the different [blank] and [blank] of [blank] electrons present in the two different types of materials.
size, energies, valence
The degree to which a substance conducts heat
thermal conductivity
The [blank] model helps answer questions about metals and semiconductors.
wave
When you compare the band gap for a red and a blue LED, what is true?
The red LED has the smallest band gap
T/F: Generally, MOs are low in energy because their electrons will be found between two nuclei.
True
T/F: Semi-metals are electrically conductive and have high melting points.
True
T/F: Semiconductors and metals are very similar in the way each forms alloys.
True
T/F: Composition of alloys are generally fixed in simple ratios.
False
T/F: For an alloy to form, the atoms must be different sizes.
False
T/F: Light can only be seen through very thin metal.
False
T/F: Metals have higher ionization energies than non-metals do.
False
T/F: Often alloys, are better conductors than either of the metals, in their pure form, that make up the alloy.
False
The source of differences between semiconductors and metal is caused by [blank].
bank gaps
Why are metals opaque?
because metals have empty, overlapping orbitals for their electrons
Nuclei surrounded by a 'sea' of electrons
metallic bonding
'Movement of electrons'
conduction
Property of absorbing photons throughout the electromagnetic spectrum
opacity
How easily light bounces off the surface of a substance.
reflectivity
a measure of resistance to current flowing through a semiconductor
resistivity
Substances that conduct electricity better than insulators but not as good as conductors.
semiconductors
Which of the following is a characteristic of metallic bonds? brittle, transparent, shiny, low melting temperature, insulatr
shiny
If GaAs forms a semiconductor like Ge, which of the following elements will form a semiconductor like Si? C and Ge, B and As, Ga and N, Al and P
Al and P
(T/F) Current can flow in all directions in an LED.
False
How do metals and semiconductors change with increasing temperature?
Metals become more resistive and semiconductors become less responsive.
Which of the following is a correct comparison of metals and semi-conductors? Metals have a larger band gap than semi-conductors, Metals' resistance increases when temperature increases while a semi-conductors resistance decreases, Semi-conductors' molecular orbitals overlap while metals' don't, Metals have more valence electrons than semi-conductors, Metals have larger electrical resistance than semi-conductors
Metals' resistance increases when temperature increases while a semi-conductors resistance decreases
Metal-metal compound
alloy
The [blank] electrons act like a [blank] between the layers of the nuclei when flattening metal with a mallet.
fluid-like, lubricant
Which of the following is NOT why alloys are useful to us today? Alloys have lower melting temperatures, have a higher conductivity rate, are less malleable, reduce weight in objects.
have a higher conductivity rate
Which of the following is NOT why alloys are useful today? alloys: have lower melting temperatures, have a higher conductivity rate, are less malleable, reduce weight in objects
have a higher conductivity rate
