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r-ruslan [8.4K]
3 years ago
7

The bottom number on each element of a on the periodic table is called

Chemistry
1 answer:
ruslelena [56]3 years ago
5 0

Answer:

On the periodic table, there are two numbers for every element: the atomic number and the atomic weight.

The numbers at the top of the square represents the number of protons present in the atom's nucleus of that element. This is called the atomic number.

For example, the atomic number for the element Krypton is 36. That means that there are 36 protons in the nucleus. If there were not 36 protons in the nucleus of that atom, that would create the atom of a completely different element. For example, if one proton was to be removed from the nucleus of the atom for the element of Krypton that atom will be an atom of the element bromine.

Explanation:

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Draw an alkyl bromide with proper stereochemistry that can be used to synthesize the given alkene as the exclusive product via a
enot [183]

Answer:

See explanation below

Explanation:

You forgot to put the picture to do so. In this case, I manage to find one, and I hope is the one you are looking for. If not, then post it again and I'll gladly help you out again.

According to the picture with the answer, we have a cyclohexane with 4 methyl groups there. Two of them are facing towards the molecule with a darker bond. This means that the alkyl bromide, should have a bromine in one of the bonds, and in order to produce an E2 reaction, this bromine should be facing in the opposite direction of the methyl groups which are facing towards. This is because an E2 reaction occurs with the less steric hindrance in the molecule. If the bromine is in the same direction as the methyl group, it will cause a lot more of work to do a reaction, and therefore, an E2 reaction. I will promote instead a E1 or a sustitution product.

Therefore the alkyl bromide should be like the one in the picture 2.

3 0
3 years ago
What two properties affect the<br> density of ocean water?
mihalych1998 [28]

Answer: temperature and salinity.

Explanation:

5 0
2 years ago
What causes differences in air pressure
shtirl [24]
Unequal heating of the atmosphere
5 0
3 years ago
Read 2 more answers
Using the periodic tables, identify the heaviest member of each of the following groups:
Lady_Fox [76]

Answer:

(a) Alkali metals: Francium (Fr)

(b) Chalcogens: Polonium (Po)

(c) Noble gases: Radon (Rn)

(d) Alkaline earth metals: Radium (Ra)

Explanation:

In the periodic table, the atomic mass increases down the group. Therefore, the last element of a group is the heaviest element of the group.

(a) alkali metals: The chemical elements that are present in group 1 of the periodic table, except hydrogen.

<u>The heaviest member of this group is francium (Fr)</u>

(b) chalcogens: The chemical elements that are present in group 16 of the periodic table

<u>The heaviest member of this group is polonium (Po)</u>

(c) noble gases:  The chemical elements that are present in group 18 of the periodic table

<u>The heaviest member of this group is radon (Rn)</u>

(d) alkaline earth metals: The chemical elements that are present in group 2 of the periodic table.

<u>The heaviest member of this group is radium (Ra)</u>

7 0
3 years ago
The half life of 226/88 Ra is 1620 years. How much of a 12 g sample of 226/88 Ra will be left after 8 half lives?
Aloiza [94]

Answer:

0.0468 g.

Explanation:

  • The decay of radioactive elements obeys first-order kinetics.
  • For a first-order reaction: k = ln2/(t1/2) = 0.693/(t1/2).

Where, k is the rate constant of the reaction.

t1/2 is the half-life time of the reaction (t1/2 = 1620 years).

∴ k = ln2/(t1/2) = 0.693/(1620 years) = 4.28 x 10⁻⁴ year⁻¹.

  • For first-order reaction: <em>kt = lna/(a-x).</em>

where, k is the rate constant of the reaction (k = 4.28 x 10⁻⁴ year⁻¹).

t is the time of the reaction (t = t1/2 x 8 = 1620 years x 8 = 12960 year).

a is the initial concentration (a = 12.0 g).

(a-x) is the remaining concentration.

∴ kt = lna/(a-x)

(4.28 x 10⁻⁴ year⁻¹)(12960 year) = ln(12)/(a-x).

5.54688 = ln(12)/(a-x).

Taking e for the both sides:

256.34 = (12)/(a-x).

<em>∴ (a-x) = 12/256.34 = 0.0468 g.</em>

8 0
3 years ago
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