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3 years ago

What is the number of valence electrons in a helium atom?

Chemistry

2 answers:

ratelena [41]3 years ago

8 0

<span>Helium has two valence electrons.</span>

Alik [6]3 years ago

5 0

Valency, the combining capacity of an element, is equal to the number of electrons needed, or required to be removed from the outermost shell of the atom of that element, to have a complete 'octet'. The helium atom has only the 1s orbital in its only shell, and it is completely filled with 2 electrons. Its electronic configuration is 1s2.<span>Therefore, helium and the other inert gases with complete octets normally do not take part in chemical reactions. They are considered as zero-valent elements.</span>

You might be interested in

Is 2 KNO₃ + H₂CO₃ → K₂CO₃ + 4 HNO₃ a balanced equation

krok68 [10]

Hey there!

The elements in this equation are K, N, O, H, and C.

Let's count how many of each are on each side to see if it is balanced.

K: 2 on the left, 2 on the right.

<em>N: 2 on the left, 4 on the right. </em>

<em>O: 9 on the left, 6 on the right. </em>

<em>H: 2 on the left, 4 on the right. </em>

C: 1 on the left, 1 on the right.

Notice that there are different amounts of N, O, and H on the left side and the right side.

This means that the equation is not balanced.

Hope this helps!

6 0

3 years ago

What element was named for the scientist who discovered the nucleus of the atom using gold foil

Artist 52 [7]

<span>rutherfordium element # 104</span>

4 0

3 years ago

Oxygen gas can be prepared by heating potassium chlorate according to the following equation:2KClO3(s)Arrow.gif2KCl(s) + 3O2(g)T

Eduardwww [97]

Answer:

Moles of potassium chlorate reacted = 0.2529 moles

The amount of oxygen gas collected will be 12.8675 g

Explanation:

(a)

We are given:

Vapor pressure of water = 17.5 mmHg

Total vapor pressure = 748 mmHg

Vapor pressure of Oxygen gas = Total vapor pressure - Vapor pressure of water = (748 - 17.5) mmHg = 730.5 mmHg

To calculate the amount of Oxygen gas collected, we use the equation given by ideal gas which follows:

$PV=nRT$

where,

P = pressure of the gas = 730.5 mmHg

V = Volume of the gas = 9.49 L

T = Temperature of the gas = $20^oC=[20+273]K=293K$

R = Gas constant = $62.3637\text{ L.mmHg }mol^{-1}K^{-1}$

n = number of moles of oxygen gas = ?

Putting values in above equation, we get:

$730.5mmHg\times 9.49L=n\times 62.3637\text{ L.mmHg }mol^{-1}K^{-1}\times 293K\\\\n=\frac{730.5\times 9.49}{62.3637\times 293}=0.3794mol$

According to the reaction shown below as:-

$2KClO_3(s)\rightarrow 2KCl(s) +3O_2(g)$

3 moles of oxygen gas are produced when 2 moles of potassium chlorate undergoes reaction.

So,

0.3794 mol of oxygen gas are produced when $\frac{2}{3}\times 0.3794$ moles of potassium chlorate undergoes reaction.

<u>Moles of potassium chlorate reacted = 0.2529 moles</u>

(b)

We are given:

Vapor pressure of water = 17.5 mmHg

Total vapor pressure = 753 mmHg

Vapor pressure of Oxygen gas = Total vapor pressure - Vapor pressure of water = (753 - 17.5) mmHg = 735.5 mmHg

To calculate the amount of Oxygen gas collected, we use the equation given by ideal gas which follows:

$PV=nRT$

where,

P = pressure of the gas = 735.5 mmHg

V = Volume of the gas = 9.99 L

T = Temperature of the gas = $20^oC=[20+273]K=293K$

R = Gas constant = $62.3637\text{ L.mmHg }mol^{-1}K^{-1}$

n = number of moles of oxygen gas = ?

Putting values in above equation, we get:

$735.5mmHg\times 9.99L=n\times 62.3637\text{ L.mmHg }mol^{-1}K^{-1}\times 293K\\\\n=\frac{735.5\times 9.99}{62.3637\times 293}=0.40211mol$

Moles of Oxygen gas = 0.40211 moles

Molar mass of Oxygen gas = 32 g/mol

Putting values in above equation, we get:

$0.037mol=\frac{\text{Mass of Oxygen gas}}{2g/mol}\\\\\text{Mass of Oxygen gas}=(0.40211mol\times 32g/mol)=12.8675g$

<u>Hence, the amount of oxygen gas collected will be 12.8675 g</u>

5 0

3 years ago

If a mass of a cube were 48.0g and its volume 24.0 cm3 what would its density be

EastWind [94]

Answer:

<h3>The answer is 2 g/cm³</h3>

Explanation:

The density of a substance can be found by using the formula

$density = \frac{mass}{volume} \\$

From the question

mass = 48 g

volume = 24 cm³

We have

$density = \frac{48}{24} \\$

We have the final answer as

Hope this helps you

5 0

3 years ago

The overall reaction in a chemical cell is shown below as the reaction takes place (look in image)

GREYUIT [131]

According to provided equation it is clear that Zn metal is oxidized from Zn⁰ into Zn²⁺ which means that Zn metal dissolves and forming Zn²⁺ solution so the correct answer is:
mass of the Zn(s) electrode decreases

8 0

3 years ago