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3 years ago

How does the number of valence electrons for elements change across a period?

Chemistry

2 answers:

kondor19780726 [428]3 years ago

8 0

Answer: Option (b) is the correct answer.

Explanation:

Valence electrons is the number of electrons present in the outermost shell of an atom.

So, when we move across a period from left to right then there will be increase in number of valence electrons.

For example, valence electrons in carbon is 4, nitrogen has 5 valence electrons, oxygen has 6 valence electrons.

Thus, we can conclude that number of valence electrons increases for elements change across a period.

NeTakaya3 years ago

4 0

D. The number increases and then decreases for noble gases

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A student placed 10.5 g of glucose (C6H12O6) in a volumetric fla. heggsk, added enough water to dissolve the glucose by swirling

aniked [119]

<u>Answer:</u> The mass of glucose in final solution is 0.420 grams

<u>Explanation:</u>

To calculate the molarity of solution, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}$ .........(1)

Initial mass of glucose = 10.5 g

Molar mass of glucose = 180.16 g/mol

Volume of solution = 100 mL

Putting values in equation 1, we get:

$\text{Initial molarity of glucose}=\frac{10.5\times 1000}{180.16\times 100}\\\\\text{Initial molarity of glucose}=0.583M$

To calculate the molarity of the diluted solution, we use the equation:

$M_1V_1=M_2V_2$

where,

$M_1\text{ and }V_1$ are the molarity and volume of the concentrated glucose solution

$M_2\text{ and }V_2$ are the molarity and volume of diluted glucose solution

We are given:

$M_1=0.583M\\V_1=20.0mL\\M_2=?M\\V_2=0.5L=500mL$

Putting values in above equation, we get:

$0.583\times 20=M_2\times 500\\\\M_2=\frac{0.583\times 20}{500}=0.0233M$

Now, calculating the mass of final glucose solution by using equation 1:

Final molarity of glucose solution = 0.0233 M

Molar mass of glucose = 180.16 g/mol

Volume of solution = 100 mL

Putting values in equation 1, we get:

$0.0233=\frac{\text{Mass of glucose in final solution}\times 1000}{180.16\times 100}\\\\\text{Mass of glucose in final solution}=\frac{0.0233\times 180.16\times 100}{1000}=0.420g$

Hence, the mass of glucose in final solution is 0.420 grams

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3 years ago

How do water particles move in a wave? A. They move forward with the wave. B. They move in a circular motion. C. They move up an

Olin [163]

Sorry if I'm wrong but I think that it is B.

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2 years ago

Citric acid (right) is concentrated in citrus fruits and plays a central metabolic role in nearly every animal and plant cell.

arlik [135]

<u>0.549 mol</u> of citric acid are in 1.50 qt of lemon juice (d = 1.09 g/mL) that is 6.82% citric acid.

<h3>What is citric acid?</h3>

Citric acid is an organic compound with a chemical formula of $HOC(CO_2H)(CH_2CO_2H)_2$ . It is a weak organic acid that is colourless. Citrus fruits naturally produce it. It is a biochemical intermediary in the citric acid cycle, which is a process that all aerobic organisms go through during metabolism.

Every year, more than two million tonnes of citric acid are produced. It is frequently employed as a chelating agent, an acidifier, and a flavouring

Citrates, which include salts, esters, and the polyatomic anion present in solution, are derivatives of citric acid. Trisodium citrate is an example of the former; triethyl citrate is an example of an ester.

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1 year ago

Determine the number of protons, neutrons and electrons in each of the following:

Kisachek [45]

Cu+ p=29 e=28 n=34
S2- p=16 e=18 n=16
Pb4+ p=82 e=78 p=125

I hope i did it right :))

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2 years ago

Find the mass in grams of 1.55 x 1023 molecules of Cl2?

forsale [732]

We are told that there are 1.55 x 10²³ molecules of Cl₂ and we need to calculate the mass of these molecules. We need to do several conversions. The easiest will be to convert the amount of molecules to the number of moles present. To do this, we need to use Avogadro's number which is 6.022 x 10²³ molecules/mole.

1.55 x 10²³ molecules / 6.022 x 10²³ molecules/mole = 0.257 moles Cl₂

Now that we have the moles of Cl₂ present, we can convert this value to a mass of Cl₂ by using the molecular mass of Cl₂. The molecular mass is 70.906 g/mol.

0.257 moles Cl₂ x 70.906 g/mol = 18.3 g Cl₂

Therefore, 1.55 x 10²³ molecules of Cl₂ will have a mass of 18.3 g.

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3 years ago