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labwork [276]
3 years ago
13

How many valence electrons does a helium atom have? what is the formula of the ion formed when potassium achieves noble-gas elec

tron configuration?
Chemistry
1 answer:
OlgaM077 [116]3 years ago
3 0

> How many valence electrons does a helium atom have?

The electron configuration of Helium is simply 1s2. We see that its outermost shell is the s shell and it contains 2 electrons, therefore the number of valence electrons is also 2.

 

> What is the formula of the ion formed when potassium achieves noble-gas electron configuration?

Potassium has a electron configuration of [Ar] 4s1. To have an electron configuration of only [Ar] which is a noble gas, the one electron from 4s1 should be removed, hence:

<span>K+</span>

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dexar [7]

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A. 266g/mol

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A colligative property of matter is freezing point depression. The formula is:

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Where:

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Replacing in (1):

0,14°C = 1×1,86°Cm⁻¹× mol Solute / 0,816kg

<em>0,0614 = mol of solute</em>.

As molar mass is defined as grams per mole of substance and the compound weights 16,0g:

16,0g / 0,0614 mol = 261 g/mol ≈ <em>A. 266g/mol</em>

I hope it helps!

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