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mel-nik [20]
2 years ago
10

How do you identify the group and period number of an element with example

Chemistry
1 answer:
11Alexandr11 [23.1K]2 years ago
6 0

The period is equal to the number of shells present in an atom.

The group number is equal to the number of valence electrons.

<h3>What is the period in the periodic table?</h3>

A period in the periodic table is a row of chemical elements.

The horizontal rows (which Mendeleev called series) are called periods and the vertical columns, are groups.

Elements having similar outer electronic configurations in their atoms are arranged in vertical columns.

The period indicates the value of n for the outermost or valence shell. The period is equal to the number of shells present in an atom. To find a period, the no. of shells =no. of periods.

Example: Na- 2,8,1 - Three shells are there, so period no. is 3.

Calcium - 2,8,8,2 - Four shells are there, so period no. is 4.

To determine the group, we need to understand some rules:

1. If the element is in s block, then the group number is equal to the number of valence electrons.

Example: Mg(12) - 2,8,2

Group = no. of valence electrons = 2

2. If the element is in the p block, then the number of the group can be determined by the formula: (number of valence electrons + 10).for groups.

Example: S(16) - 2,8,6

Group = no. of valence electrons+ 10 = 6+ 10 = 16

3. If the element is in the d block, then the number of the group can be determined by the formula: number of electrons in(n−1)d subshell + (number of electrons in (n)s subshell).

Example: Fe(26):

[Ar]3d^64s^2

Group = number of electrons in(n−1)d subshell + (number of electrons in (n)s subshell) = 6+2 = 8

4. If the element is in the f block, then the number of the group is always 3.  Example: Cerium (58) belongs to the 3rd group.

Learn more about the period in the periodic table:

brainly.com/question/11965624

#SPJ1

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6.
GuDViN [60]

Answer:

A phosphorus atom forms a P3- ion by gaining three electrons.

here

4 0
2 years ago
In two or more complete sentences, develop a logical argument to either support or refute the following statement. Be sure to pr
Yuri [45]

We use logic every day to figure out test questions, plan our budgets, and decide who to date. We borrow from the vocabulary of logic when we say, "Brilliant deduction" or even "I don't want to argue about it." In the study of logic, however, each of these terms has a specific definition, and we must be clear on these if we are to communicate.

Vocabulary

Proposition --

T or F in an argument, but not alone. Can be a premise or conclusion. Is not equal to a sentence.

Premise --

Proposition used as evidence in an argument.

Conclusion --

Proposition used as a thesis in an argument.

Argument --

A group of propositions of which one is claimed to follow from the others.

Induction --

A process through which the premises provide some basis for the conclusion

Deduction --

A process through which the premises provide conclusive proof for the conclusion.

Argument Indicators: Premise Indicators: Conclusion Indicators:

should

must

ought  

necessarily

since  

because

for  

as

inasmuch as  

for the reason that

first ...

therefore

hence

thus

so

consequently  

it follows that  

one may infer

one may conclude

When dealing with persuasive writing, it will be helpful for you to outline the argument by premises and conclusions. By looking at the structure of the argument, it is easy to spot logical error.

Universities are full of knowledge. The freshmen bring a little in, and the seniors take none away, and knowledge accumulates.

-- Harvard President A. L. Lowell

Premise 1

Premise 2

Premise 3

Conclusion Freshmen bring a little (knowledge) in

Seniors take none away

Knowledge accumulates

Universities are full of knowledge

Example 2

(Here, the conclusion of one argument is used as a premise in another. This is very common.)

Even though there may be a deceiver of some sort, very powerful and very tricky, who bends all his efforts to keep me perpetually deceived, there can be no slightest doubt that I exist, since he deceives me; and let him deceive me as much as he will, he can never make me be nothing as long as I think I am something. Thus, after having thought well on this matter, and after examining all things with care, I must finally conclude and maintain that this proposition: I am, I exist, is necessarily true every time that I pronounce it or conceive it in my mind.

-- Rene Descartes, *Meditations*

Argument 1 Premise 1:

Conclusion of Argument 1

Argument 2 Premise 1:

Conclusion:

To be deceived ... I must exist

When I think that I exist I cannot be  

deceived about that

I am, I exist, is necessarily true ... .

Exercises

Find the Arguments and Outline them in These Statements:

1. Ask the same for me, for friends should have all things in common.

-- Plato, Phaedrus

2. Matter is activity, and therefore a body is where it acts; and because every particle of matter acts all over the universe, every body is everywhere.

-- Collingwood, The Idea of Nature

3. The citizen who so values his "independence" that he will not enroll in a political party is really forfeiting independence, because he abandons a share in decision©making at the primary level: the choice of the candidate.

-- Felknor, Dirty Politics

Reaching Logical Conclusions

This article is reprinted from pages 78-79 of Pearson-Allen: Modern Algebra , Book One. In the book it is one of several between-chapter articles that add interest and provike thought on subjects related to the topics discussed in the text.

Consider the two statements:

1. Any member of a varsity squad is excused from physical education.

2. Henry is a member of the varsity football squad.

Our common sense tells us that if we accept these two statement as true, then we must accept the following third statement as true:

3. Henry is excused from physical education.

We say that the third statement follows logically from the other two.

In drawing logical conclusions it does not matter whether the statements we accept as true are reasonable or sensible. This is because we depend entirely upon the form of the statements and not upon what we are talking about. Thus, if we accept the following statements as true:

1. All whales are mammals;  

2. All mammals are warm-blooded animals;  

3. All warm-blooded animals are subject to colds;

then we must conclude that


8 0
3 years ago
What is catalyst? Write its types.​
Step2247 [10]

Answer:

A catalyst is a chemical substance that alters the rate of chemical reaction not consumed by the reaction. Hence, a catalyst can be recovered chen unchanged at the ends of chemical reaction. Catalyst can be divided into two typ the basis whether it speeds up or slowdowns the rate of chemical reaction. The positive catalyst and negative catalyst.

5 0
3 years ago
Read 2 more answers
Consider the titration of 1L of 0.36 M NH3 (Kb=1.8x10−5) with 0.74 M HCl. What is the pH at the equivalence point of the titrati
worty [1.4K]

Answer:

C

Explanation:

The question asks to calculate the pH at equivalence point of the titration between ammonia and hydrochloric acid

Firstly, we write the equation of reaction between ammonia and hydrochloric acid.

NH3(aq)+HCl(aq)→NH4Cl(aq)

Ionically:

HCl + NH3 ---> NH4  +  Cl-

Firstly, we calculate the number of moles of  the ammonia  as follows:

from c = n/v and thus, n = cv = 0.36 × 1 = 0.36 moles

At the equivalence point, there is equal number of moles of ammonia and HCl.

Hence, volume of HCl = number of moles/molarity of HCl = 0.36/0.74 = 0.486L

Hence, the total volume of solution will be 1 + 0.486 = 1.486L

Now, we calculate the concentration of the ammonium ions = 0.36/1.486 = 0.242M

An ICE TABLE IS USED TO FIND THE CONCENTRATION OF THE HYDROXONIUM ION(H3O+). ICE STANDS FOR INITIAL, CHANGE AND EQUILIBRIUM.

                 NH4+      H2O     ⇄  NH3        H3O+

I                0.242                           0             0

C                 -X                              +x              +X

E             0.242-X                          X              X

Since the question provides us with the base dissociation constant value K b, we can calculate the acid dissociation constant value Ka

To find this, we use the mathematical equation below

K a ⋅ K b    = K w

 

, where  K w- the self-ionization constant of water, equal to  

10 ^-14  at room temperature

This means that you have

K a = K w.K b   = 10 ^− 14 /1.8 * 10^-5 =  5.56 * 10^-10

Ka = [NH3][H3O+]/[NH4+]

= x * x/(0.242-x)

Since the value of Ka is small, we can say that 0.242-x ≈  0.242

Hence, K a = x^2/0.242 = 5.56 * 10^-10

x^2 = 0.242 * 5.56 * 10^-10 = 1.35 * 10^-10

x = 0.00001161895

[H3O+] = 0.00001161895

pH = -log[H3O+]

pH = -log[0.00001161895 ] = 4.94

7 0
3 years ago
The aldol reaction is catalyzed by acid as well as base. What is the reactive nucleophile in the acid-catalyzed aldol reaction
svp [43]

Answer:

The reactive nucleophile is Ketone.

Explanation:

In organic chemistry, The process of acid - catalyzed aldol condensation starts from when ketone (or any aldehyde) is converted to an -enol, after which it attacks another ketone/aldehyde that has already been activated by parbonyl oxygen protonation.

The process of this is that first of all the ketone undergoes tautomerization to form -enol. Thereafter, the other carbonyl will undergo protonation which makes the carbon activated towards attack. Now, the nucleophilic enol will be added to the carbonyl in a [1,2]-addition reaction and we will now use deprotonation to obtain the neutral Aldol product.

Now, since only the ketone can produce an -enol, thus it is the nucleophile as aldehydes are better electrophiles

4 0
2 years ago
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