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Svetradugi [14.3K]

3 years ago

11

Consider the two electron arrangements for neutral atoms A and B. Are atoms A and B the same element? A - 1s2, 2s2, 2p6, 3s1 B -

1s2, 2s2, 2p6, 5s1 no yes indeterminate

1 answer:

iogann1982 [59]3 years ago

3 0

✨✨✨✨✨✨✨✨✨✨✨✨

<h2><em><u>Technically yes but no because you have to fill the 3s orbital before the 5s orbital</u></em></h2>

<em><u>✨</u></em><em><u>✨</u></em><em><u>✨</u></em><em><u>✨</u></em><em><u>✨</u></em><em><u>✨</u></em><em><u>✨</u></em><em><u>✨</u></em><em><u>✨</u></em><em><u>✨</u></em><em><u>✨</u></em><em><u>✨</u></em>

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How many atoms are there in 8.88 g Si?

Mariana [72]

Answer:

$\boxed {\boxed {\sf 1.90 \times 10^{23} \ atoms \ Si}}$

Explanation:

We are asked to find how many atoms are in 8.88 grams of silicon.

<h3>1. Grams to Moles </h3>

First, we convert grams to moles. We use the molar mass or the mass of 1 mole of a substance. These values are found on the Periodic Table as they are equal to the atomic masses, but the units are grams per mole instead of atomic mass units.

Look up silicon's molar mass.

Si: 28.085 g/mol

We will convert using dimensional analysis. Set up a conversion factor with the molar mass.

$\frac { 28.085 \ g \ Si}{1 \ mol \ Si}$

We are converting 8.88 grams of silicon to moles, so we multiply by this value.

$8.88 \ g \ Si *\frac { 28.085 \ g \ Si}{1 \ mol \ Si}$

Flip the fraction so the units of grams of silicon cancel.

$8.88 \ g \ Si *\frac{1 \ mol \ Si} { 28.085 \ g \ Si}$

$8.88 *\frac{1 \ mol \ Si} { 28.085 }$

$\frac {8.88} { 28.085 } \ mol \ Si$

$0.316183015845 \ mol \ Si$

<h3>2. Moles to Atoms </h3>

Next, we convert moles to atoms. We use Avogadro's Number or 6.022 × 10²³. This is the number of particles (atoms, molecules, formula units, etc.) in 1 mole of a substance. In this case, the particles are atoms of silicon.

Set up another conversion factor.

$\frac {6.022 \times 10^{23} \ atoms \ Si}{1 \ mol \ Si}$

Multiply by the number of moles we calculated.

$0.316183015845\ mol \ Si *\frac {6.022 \times 10^{23} \ atoms \ Si}{1 \ mol \ Si}$

The units of moles of silicon cancel.

$0.316183015845 * \frac {6.022 \times 10^{23} \ atoms \ Si}{1}$

$0.316183015845 * {{6.022 \times 10^{23} \ atoms \ Si}$

$1.90405412 \times 10^{23} \ atoms \ Si$

<h3>3. Significant Figures</h3>

The original measurement of 8.88 grams has 3 significant figures, so our answer must have the same.

For the number we calculated, that is the hundredth place. The 4 in the thousandth place tells us to leave the 0 in the hundredth place.

$1.90 \times 10^{23} \ atoms \ Si$

<u>8.88 grams of silicon contains 1.90 ×10²³ atoms of silicon.</u>

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2 years ago

HEY EVERYONE its poofett my account got deleted for no absolute reason! >:D

PilotLPTM [1.2K]

Answer:

am very sorry

Explanation:

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2 years ago

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In the lab you measure a clean dry crucible and cover to be 24.36 grams. You obtain a 2cm piece of pure magnesium metal. After s

mart [117]

Answer:

1) 0.3g Mg

2)0.5g MgO

3)0.2g O

4)0.01mol Mg & 0.01mol O

5)0.01mol MgO

6) Empirical formula MgO

Explanation:

The mass og Mg is obtained by substracting 24.36g from 24.66g:

24.66 - 24.36 = 0.3g Mg

The ignition of Mg means that it's reacting with oxygen to form an oxide. The increase in the crucible mass after the Mg ignition is due to the addition of oxygen. However, the addition of few drops of water produces a new compound: a hydroxide. According to the oxidation state og Mg (2+), the only magnesium oxide possible is MgO. It happens because the oxidation state of oxygen in oxides is 2-. Which means that just one oxygen atom is required to electrically neutralize one magnesium atom.

We can use a conversion factor to know how much MgO is made from from 0.3 g of Mg:

$0.3g Mg$ * $\frac{16gO}{24.3gMg}$ = 0.2g O

Thereby the mass of the oxide is 0.2g O + 0.3g Mg = 0.5g MgO

We convert the mass of oxygen and magnesium to the respective amounts in moles by using conversion factors:

$0.2g O$ * $\frac{1 mol O}{16g O}$ = 0.01mol O

$0.3g Mg$ * $\frac{1mol Mg}{24.3g Mg}$ = 0.01mol Mg

The moles of MgO can be obtained from:

$0.5g MgO$ * $\frac{1mol MgO}{40.3g MgO}$ = 0.01mol MgO

To obtain the empirical formula, the amount fo moles of each elements must be divided by the smallest one, in this case, 0.01.

The result for both number of Mg atoms and O atoms is 1. This can be interpreted to mean that there is a Mg atom for each O atom forming the formula unit of the compound.

The step when water is added to the compound resulting after heating does not affect the calculations necessary for the magnesium oxide.

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2 years ago

Protein x has an absorptivity of 0.4 ml·mg-1 ·cm-1 at 280 nm. What is the absorbance at 280 nm of a 2.0 mg ·ml-1 solution of pro

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Absorbance measures the ability of the substance to absorb light at a specific wavelength.

Absorbance is also equal to the product of molar absorptivity, path length and molar concentration.

The mathematical expression is given as:

$A= \epsilon l c$ (1)

where, A = absorbance

$\epsilon$ = molar absorptivity

l = path length

c = molar concentration.

The above formula is said to Beer's Law.

Absorptivity of protein x = $0.4 mLmg^{-1}cm^{-1}$

Path length = 1 cm

Molar concentration = $2.0 mg mL^{-1}$

Put the values in formula (1)

$Absorbance at 280 nm = 0.4 mL mg^{-1}cm^{-1}\times 1 cm \times 2.0 mg mL^{-1}$

= $0.8$

Thus, absorbance at 280 nm = $0.8$

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3 years ago

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Answer:

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Explanation:

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