What property of these items do cm or mm measure: length, volume, mass or temperature?
1 answer:
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Answer:
(a) Cr²⁺: 1s² 2s²2p⁶ 3s²3p⁶ 3d⁴; (b) eight
Explanation:
(a) Electron configuration of Cr
(i). Locate chromium in the Periodic Table.
It's Element 24, so in Period 4, Group 3.
(ii). Write its electron configuration
Remember that Cr is one of those exceptions to the Aufbau principle.
Instead of the predicted electron configuration of [Ar] 4s²3d⁴, we get the configuration [Ar] 4s3d⁵.
The reason is that this this configuration minimizes electron repulsion.
(b) Write the electron configuration for Cr²⁺.
Now, we must remove two electrons from a chromium atom.
The electron in the 4s orbital is removed first, because this orbital is further from the nucleus, making electrons easier to remove.
So, we remove the 4s electron, and then a 3d electron.
The electron configuration of Cr²⁺ is
[Ar]3d⁴ or 1s² 2s²2p⁶ 3s²3p⁶ 3d⁴
(c). Electrons with n + l = 3
The orbitals with n + l = 3 are those covered by the third arrow down in the order of orbital energies:
2p (n = 2, l = 1) and 3s (n = 3, l = 0)
The 2p orbitals can hold six electrons, and the 3s orbital can hold two.
Both subshells are filled in a Cr²⁺ ion, so there are eight electrons
with n+ l = 3.
Answer:
Most radio waves have wavelengths between 1 mm and 100 km.
A cooling curve shows A. how the temperature of a substance falls as heat is removed.
Explanation:
<em>Radio waves</em> are the longest of all the waves in the electromagnetic spectrum.
Most have wavelengths between 1 mm and 100 km, although there is no upper limit.
Some radio waves have wavelengths of 10 000 km.
A <em>cooling curve</em> (see image below) shows how the temperature of a substance falls as it is cooled.
In Option E., a decrease in temperature would cause an energy <em>loss</em>.
Options B., C., and D. involve the <em>addition of heat</em>.
