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3 years ago

17) The elements sodium, magnesium,and silicon

Chemistry

2 answers:

irakobra [83]3 years ago

8 0

A period is a horizontal row and therefore these elements are all in the same period.

If you pull up an image of the periodic table, you will see that all of them are in the same row.

They are not isotopes of each other because an isotope is the same element with a different number of neutrons (example: carbon-12, carbon-13).

Hopefully I helped :)

Murljashka [212]3 years ago

7 0

Answer:

B) are in the same period of elements.

Explanation:

The elements sodium, magnesium, and silicon

A) are isotopes of each other . NO. Isotopes are 2 or more forms of the same element, with a different number of neutrons.

B) are in the same period of elements. YES.

Let's consider the electron configuration of these elements.

₁₁Na 1s² 2s² 2p⁶ 3s¹

₁₂Mg 1s² 2s² 2p⁶ 3s²

₁₄Si 1s² 2s² 2p⁶ 3s² 3p²

Since the valence electrons are in the level 3, they all belong to the third period in the periodic table.

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Why do we use an object's mass, rather than its weight, to indicate the amount of matter it contains?

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3 years ago

Read 2 more answers

How many minutes will it take for a car traveling 74 miles per hour to cover 6.50 kilometers?

Dvinal [7]

Answer:

3.27 minutes

Explanation:

To solve this problem we will first convert miles/hour to km/min. For this purpose we will require following reference conversions as;

1 Mile = 1.60934 Km

And,

1 Hour = 60 min

Therefore,

As,

1 Mile = 1.60934 Km

Then,

74 Miles = X Km

Solving for X,

X = 74 miles × 1.60934 Km ÷ 1 mile

X = 119.10 Km

Therefore,

119.10 Km were travelled in = 60 min

So,

6.50 Km will be travelled in = X min

Solving for X,

X = 60 min × 6.50 Km ÷ 119.10 Km

X = 3.27 minutes

4 0

4 years ago

A student measures out exactly 0.105 g of salicylic acid and runs the experiment as dictated in the lab manual. They obtain 0.11

scoray [572]

Answer: The percent yield of the reaction is 8.10 %.

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

Given mass of salicylic acid = 0.105g

Molar mass of salicylic acid = 138.12 g/mol

Putting values in equation 1, we get:

$\text{Moles of salicylic acid}=\frac{0.105g}{138.12g/mol}=0.0079mol$

The chemical equation for the formation of aspirin from salicylic acid follows:

$\text{Salicylic acid + Acetic anhydride}\rightarrow \text{Aspirin + Acetic acid}$

By Stoichiometry of the reaction:

1 mole of salicylic acid produces 1 mole of aspirin

So, 0.0076 moles of salicylic acid will produce = $\frac{1}{1}\times 0.0076=0.0076mol$ of aspirin

Now, calculating the mass of aspirin from equation 1, we get:

Molar mass of aspirin = 180.16 g/mol

Moles of aspirin = 0.0076 moles

Putting values in equation 1, we get:

$0.0076mol=\frac{\text{Mass of aspirin}}{180.16g/mol}\\\\\text{Mass of aspirin}=(0.0076mol\times 180.16g/mol)=1.37g$

To calculate the percentage yield of aspirin, we use the equation:

$\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100$

Experimental yield of aspirin = 0.111 g

Theoretical yield of aspirin = 1.37 g

Putting values in above equation, we get:

$\%\text{ yield of aspirin}=\frac{0.111g}{1.37g}\times 100\\\\\% \text{yield of aspirin}=8.10\%$

Hence, the percent yield of the reaction is 8.10 %.

6 0

3 years ago