Pyridine rings can also under electrophilic aromatic substitution. given 2-methoxypyridine below, draw the expected major produc
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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:
See below!
Explanation:
A. The picture of the graph is attached. You can tell the amount of protons in an element by looking at the periodic table. The elements are ordered by the number of protons in an element.
B. Carbon and silicon are at the peaks of the chart. The peak is the highest point in a graph.
C. The elements belong to the non-metal group.
D. The halogens are non-metals, and their vapors are colorless.
The halogens are toxic to humans.
Halogen molecules are made of two atoms; they are diatomic.
Halogens react with non-metals to form crystalline compounds that are salts.
The halogens get less reactive going down the group on the periodic table.
Halogens can bleach vegetable dyes and kill bacteria.
E. The picture of the table is attached. To figure which numbers to put where, you need to pay attention to the other numbers. The halogens follow a trend with each of these properties. You have to put in the numbers that fit in among the other numbers.
