Answer:
Isotopes of an element share the same number of protons but have different numbers of neutrons. Let's use carbon as an example. There are three isotopes of carbon found in nature – carbon-12, carbon-13, and carbon-14. All three have six protons, but their neutron numbers - 6, 7, and 8, respectively - all differ.
Explanation:
Answer:
Below are the statements which are true about the structure of the periodic table:
B: The inner transition elements are placed at the bottom of the periodic table for easy viewing.
D: The distribution of electrons in energy levels is responsible for the shape of the periodic table.
Explanation:
Point A:
As we know that in a periodic table there are 7 period s and 18 groups. So, the number of periods is evidently lesser than the number of groups. But the shape of periodic table is regular and rectangular so point A is false.
Point B:
The inner transition elements or -f block elements are put at the bottom for easy viewing. These are the elements that have the valence electrons only in the f-orbital's. Therefore, they are placed separately at the bottom side of the table so that they can be easily viewed or studied from there. So, point B is true.
Point C:
If we talk about option C, then it is very clear and true that considering a rectangular shape of the periodic table, the groups are vertically arranged and periods are horizontally arranged, therefore it is false.
Point D:
Atoms of all elements have definite electronic distribution in different energy levels like s, p d or f. This is a very prominent feature of periodic tale that elements are divided in specific blocks, s, p, d and f based on their electronic configurations. Therefore, it is true.
Point E:
We also know that no. of metals in a periodic table are more than the no. of non metals like almost 91 out of 118 elements are metals in periodic table. Therefore, the point E "Nonmetals take up more than half the area of the periodic table." is false.
Hope it helps!
<span>You have to use a Newman projection to make sure that the H on C#2 is anti-coplanar with the Br on C#1. (Those are the two things that are going to be eliminated to make the alkene.)
My Newman projection looks like this when it's in the right configuration:
Front carbon (C#2) has ethyl group straight up, H down/left, and CH3 down/right
Back carbon (C#1) has H straight down, Ph up/left, and Br up/right.
Then when you eliminate the H from C#2 and the Br from C#1, you will have Ph and the ethyl group on the same side of the molecule, and you'll have the remaining H and CH3 on the same side of the molecule.
This is going to give you (Z)-2-methyl-1-phenyl-1-butene.</span>
