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3 years ago

How does the modern periodic table arrange elements?

Chemistry

1 answer:

viva [34]3 years ago

5 0

Answer:

The periodic table of the elements is ordered in increasing order of the atomic number of the elements (this is their number of protons) and according to the similarity of their properties.

Explanation:

To classify the similarity in the properties, the elements are arranged in 7 rows, periodic calls, and in 18 columns, called groups.

The chemical elements are ordered according to their properties from left to right and from top to bottom.

In the same group, all elements have the same number of electrons in their last layer. This makes the chemical properties of the elements very similar.

The period that an element occupies coincides with its last electronic layer. That is, an element with five electronic layers will be in the fifth period. This generates that the elements that are in the same row have different properties but similar masses.

The table is also divided into four groups, according to the orbital that the outermost electrons are occupying, and these groups are named according to the letter of the orbital referred to.

In summary, due to this classification by similarity in their characteristics, the elements are divided into three broad categories: metals, metalloids and nonmetals, which at the same time are divided into subgroups.

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The heats of combustion of ethane (C2H6) and butane (C4H10) are 52 kJ/g and 49 kJ/g, respectively. We need to produce 1.000 x 10

LekaFEV [45]

Answer :

(1) The number of grams needed of each fuel $(C_2H_6)\text{ and }(C_4H_{10})$ are 19.23 g and 20.41 g respectively.

(2) The number of moles of each fuel $(C_2H_6)\text{ and }(C_4H_{10})$ are 0.641 moles and 0.352 moles respectively.

(3) The balanced chemical equation for the combustion of the fuels.

$C_2H_6+\frac{7}{2}O_2\rightarrow 2CO_2+3H_2O$

$C_4H_{10}+\frac{13}{2}O_2\rightarrow 4CO_2+5H_2O$

(4) The number of moles of $CO_2$ produced by burning each fuel is 1.28 mole and 1.41 mole respectively.

The fuel that emitting least amount of $CO_2$ is $C_2H_6$

Explanation :

Part 1 :

First we have to calculate the number of grams needed of each fuel $(C_2H_6)\text{ and }(C_4H_{10})$ .

As, 52 kJ energy required amount of $C_2H_6$ = 1 g

So, 1000 kJ energy required amount of $C_2H_6$ = $\frac{1000}{52}=19.23g$

and,

As, 49 kJ energy required amount of $C_4H_{10}$ = 1 g

So, 1000 kJ energy required amount of $C_4H_{10}$ = $\frac{1000}{49}=20.41g$

Part 2 :

Now we have to calculate the number of moles of each fuel $(C_2H_6)\text{ and }(C_4H_{10})$ .

Molar mass of $C_2H_6$ = 30 g/mole

Molar mass of $C_4H_{10}$ = 58 g/mole

$\text{ Moles of }C_2H_6=\frac{\text{ Mass of }C_2H_6}{\text{ Molar mass of }C_2H_6}=\frac{19.23g}{30g/mole}=0.641moles$

and,

$\text{ Moles of }C_4H_{10}=\frac{\text{ Mass of }C_4H_{10}}{\text{ Molar mass of }C_4H_{10}}=\frac{20.41g}{58g/mole}=0.352moles$

Part 3 :

Now we have to write down the balanced chemical equation for the combustion of the fuels.

The balanced chemical reaction for combustion of $C_2H_6$ is:

$C_2H_6+\frac{7}{2}O_2\rightarrow 2CO_2+3H_2O$

and,

The balanced chemical reaction for combustion of $C_4H_{10}$ is:

$C_4H_{10}+\frac{13}{2}O_2\rightarrow 4CO_2+5H_2O$

Part 4 :

Now we have to calculate the number of moles of $CO_2$ produced by burning each fuel to produce 1000 kJ.

$C_2H_6+\frac{7}{2}O_2\rightarrow 2CO_2+3H_2O$

From this we conclude that,

As, 1 mole of $C_2H_6$ react to produce 2 moles of $CO_2$

As, 0.641 mole of $C_2H_6$ react to produce $0.641\times 2=1.28$ moles of $CO_2$

and,

$C_4H_{10}+\frac{13}{2}O_2\rightarrow 4CO_2+5H_2O$

From this we conclude that,

As, 1 mole of $C_4H_{10}$ react to produce 4 moles of $CO_2$

As, 0.352 mole of $C_4H_{10}$ react to produce $0.352\times 4=1.41$ moles of $CO_2$

So, the fuel that emitting least amount of $CO_2$ is $C_2H_6$

5 0

3 years ago

I really need help ! This is science

lina2011 [118]

Answer:

7. genetics because hereditary is not the study of hereditary.

8. is hereditary because it is the study of how things pass on to next generation what is inherited.

7 0

3 years ago

Read 2 more answers

How did coroners handle their responsibilities in the early 1900s? Why was there a need for significant change in the job?

Lorico [155]

Answer:

In the twentieth century, criminologists and forensics strive to summarize the preceding discoveries. In different countries tendencies are beginning to manifest that increase the field of criminological activity in different branches such as criminalistics in Germany; others, penology; and others like the United States, weighed the study as a whole of the science of crime and the science of social reaction provoked by it. In this century, criminology and forensic science had a notable influence on the evolution of criminal law.

Starting in the mid-20th century, a paradigm shift in forensic criminological science was presented, focusing on the study of three aspects: criminal processes, the social environment, and the victim.

Other factors that were taken into account were biosecurity care, which began to have great relevance and greater care since they began to discover infectious diseases transmitted by cadavers to humans.

Approximately in 1939 it was discovered that anthropometric measurements are values that present similarities between different skeleton patterns.

Explanation:

Legal dentistry also addresses the aspect related to “professions” and people's habits, for example, by 1925 it was already possible to identify a smoker by the coloration that the teeth took and the wear on the incisors and canines where the cigar rested. The morphological characteristics of the teeth were, in many cases, used to identify those they called "degenerates", who were the ones who went outside the guidelines of psychic "normality" of the time; among these were prostitutes, thieves, who according to the author had a considerable volume in the molars, the canines were triangular and long, like the upper central incisors that in some reached 8 mm.

3 0

3 years ago

Which statement describes how NO2- reacts in this equilibrium:

WITCHER [35]

The statement which describes how NO2- reacts in this equilibrium:
H2SO3(aq) + NO2-(aq) HSO3-(aq) + HNO2(aq
is the second option - B. as a Brønsted-Lowry base by accepting a proton.
This is because bases take proton H+ in order to become HNO2.

6 0

3 years ago

Read 2 more answers

By how much will the ph change if 0.025 mol of hcl is added to 1.00 l of the buffer that contains 0.15 m hc2h3o2 and 0.25 m c2h3

Setler [38]

According to the reaction equation:

CH3COO- + H+ → CH3COOH

initial 0.25 0.15

change - 0.025 + 0.025

Equ (0.25-0.025) (0.15 + 0.025)

first, we have to get moles acetate and moles acetic acid:

moles of acetate = 0.25 - 0.025 = 0.225 moles

∴ [CH3COO-] = 0.225 mol / 1 L = 0.225 M

moles of acetic acid = 0.15 + 0.025 = 0.175 moles

∴ [ CH3COOH] = 0.175 mol / 1L = 0.175 M

Pka = -㏒ Ka

= -㏒ 1.8 x 10^-5

= 4.74

from H-H equation we can get the PH value:

PH = Pka + ㏒ [acetate / acetic acid]

PH = 4.74 + ㏒[0.225/0.175]

∴ PH = 4.8

3 0

3 years ago