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3 years ago

What is the valence number of an element that has 3 electron in its outermost shell?

1 answer:

5 0

Lithium has 3 electrons --- 2 in the first shell, and 1 in the second shell (so one valence electron). Beryllim has 4 electrons --- 2 in the first shell, and 2 in the second shell (so two valence electrons). Boron has 5 electrons --- 2 in the first shell, and 3 in the second shell (so three valence electrons).Jul 27, 2019
Hope that helps and may I get brainliest?

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Atoms of which two elements have a combined total of 23 protons?

Alik [6]

Answer:

Sodium, Na, and magnesium, Mg

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3 years ago

How does nuclear fission produce energy answer.com?

scZoUnD [109]

Nuclear energy originates from splitting of uranium atoms a process called fission. This generates heat to produce steam.

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3 years ago

Read 2 more answers

How many bonding and non bonding domains are on the central atom in NH2-

siniylev [52]

1bonding and 3non-bonding

(Refer to the attachment for structure

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2 years ago

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A scientist wants to make a solution of tribasic sodium phosphate, Na3PO4, for a laboratory experiment. How many grams of Na3PO4

san4es73 [151]

Answer:

83.20 g of Na3PO4

Explanation:

1 mole of Na3PO4 contains 3 moles of Na+.

Mole of Na ion to be prepared = Molarity x volume

= 0.700 x 725/1000

= 0.5075 mole

If 1 mole of Na3PO4 contains 3 moles of Na ion, then 0.5075 Na ion will be contained in:

0.5075/3 x 1 = 0.1692 mole of Na3PO4

mole of Na3PO4 = mass/molar mass = 0.1692

Hence, mass of Na3PO4 = 0.1692 x molar mass

= 0.1692 x 163.94

= 83.20 g.

83.20 g of Na3PO4 will be needed.

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3 years ago

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CaO + H2O -> Ca(OH)2

yawa3891 [41]

The % yield of Ca(OH)₂ : 62.98%

<h3>Further eplanation </h3>

Percent yield is the compare of the amount of product obtained from a reaction with the amount you calculated

General formula:

Percent yield = (Actual yield / theoretical yield )x 100%

An actual yield is the amount of product actually produced by the reaction. A theoretical yield is the amount of product that you calculate from the reaction equation according to the product and reactant coefficients

Reaction

CaO + H₂O ⇒ Ca(OH)₂

mass CaO= 4.2 g

mol CaO(MW=56,0774 g/mol) :

$\tt mol=\dfrac{mass}{MW}\\\\mol=\dfrac{4.2}{56,0774 g/mol}\\\\mol=0.075$

mol Ca(OH)₂ based on mol CaO

mol ratio CaO : Ca(OH)₂,= 1 : 1, so mol Ca(OH)₂ = 0.075

mass Ca(OH)₂(MW=74,093 g/mol) ⇒ theoretical

$\tt mass=mol\times MW\\\\mass=0.075\times 74,093 g/mol\\\\mass=5.557~g$

% yield :

$\tt =\dfrac{actual}{theoretical}\times 100\%\\\\=\dfrac{3.5}{5.557}\times 100\%\\\\=62.98\%$

8 0

2 years ago