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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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Which missing item would complete this alpha decay reaction?<br><br> 257/100 Fm= ________+4/2He
maria [59]

Answer: ₉₈²⁵³Cf

253 is a superscript to the left of the symbol, Cf, which represents the mass number, and 98 is a subscript to the left of the same symbol, which represents the atomic number.

Explanation:

1) The alpha decay equation shows that the isotope Fm - 257, whose nucleus has 100 protons and 157 neutrons, emitted an alpha particle (a nucleus with 2 protons and 2 neutrons).

2) Therefore:

i) the mass number decreased in 4, from 257 to 257 - 4 = 253.

2) the atomic number decreased in 2, from 100 to 100 - 2 = 98.

3) Hence the formed atom has atomic number 98, which is californium, Cf, and the isotope is californium - 253.

4) The item that completes the given alpha decay reaction is:

₉₈²⁵³ Cf.

5) The complete alfpha decay reaction is:

₁₀₀²⁵⁷ Fm → ₉₈²⁵³Cf + ₂⁴He

You can verify the mass balance:

257 = 253 + 4, and

100 = 98 + 2

4 0
3 years ago
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9. Based on your work with benzoic acid, show the reaction between salicylic acid and potassium hydroxide. Label the acid, base,
shepuryov [24]

Answer:

Explanation:

Salicylic Acid:

Salicylic Acid is an hydroxy acid that is found as a natural compound in plants.  It's IUPAC name is 2-hydroxybenzoic acid. Salicylic acid has an odorless white to light tan solid color. It sinks and mixes very slow with water.

Acid:  An acid is a substance that produce hydrogen ion or proton when dissolved in water

Base: A base is a substance that will neutralize an acid to yield salt and  water

Conjugate Base: This is a substance formed when an acid loses an hydrogen ion or proton when it dissolved in water.

Conjugate Acid: This is a substance formed when a base accept a proton from from any acid, when it dissolved in water.

Reaction between salicylic acid and potassium hydroxide

HOC₆H₄COOH(aq) + KOH(aq) ⇄ HOC₆H₄COOK(aq) + H₂O(l)

Acid ⇒ HOC₆H₄COOH (salicylic acid)

Base ⇒ KOH (potassium hydroxide)

Conjugate acid ⇒ H₂O (water)

conjugate base ⇒ HOC₆H₄COOK (  2-hydroxypotasium benzoate)

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3 years ago
Forensic science is the application of science to what field?
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B.) Criminal Justice
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Why males on average have VO2max than females?
katrin [286]
The average sedentary male will achieve a VO2 max of approximately 35 to 40 mL/Kg/min. And the average sedentary female will score a VO2 max of between 27 an 30 mL/Kg/min.
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Gases with high molecular weights diffuse more slowly than gases with lower molecular weights.
Rom4ik [11]
The answer to this item is TRUE. This can be explained through the Graham's law. This law states that the rate at which gases diffuse is inversely proportional to the square root of their densities which is also related to their molecular masses. 
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