Chemistry, 27.02.2021 03:10 majestyic1207

Determine the mass in grams of 2.71 x 10^21 atoms of arsenic if the mass of one mole is 74.92g

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Answer from: herbal420medici

0.337 g As

General Formulas and Concepts:

Math

Pre-Algebra

Order of Operations: BPEMDAS

Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to Right

Chemistry

Atomic Structure

Reading a Periodic TableMolesAvogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

Stoichiometry

Using Dimensional AnalysisExplanation:

Step 1: Define

[Given] 2.71 × 10²¹ atoms As

[Solve] grams As

Step 2: Identify Conversions

Avogadro's Number

[PT] Molar Mass of As - 74.92 g/mol

Step 3: Convert

[DA] Set up: $\displaystyle 2.71 \cdot 10^{21} \ atoms \ As(\frac{1 \ mol \ As}{6.022 \cdot 10^{23} \ atoms \ As})(\frac{74.92 \ g \ As}{1 \ mol \ As})$ [DA] Multiply/Divide [Cancel out units]: $\displaystyle 0.337152 \ g \ As$

Step 4: Check

Follow sig fig rules and round. We are given 3 sig figs.

0.337152 g As ≈ 0.337 g As

Answer from: Quest

assuming that your periodic table has eighteen columns, you should highlight the four elements in the third column from the left of the table.

explanation

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the $3d$ have energy higher than those in the $4 s$ orbital while lower than those of the $4 p$ orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the $4s$ orbital is therefore filled right after $3p$ orbitals and before $3 d$ orbitals.

potassium has electron configuration $[\text{ar}] 4 s^{1}$ and calcium $[\text{ar}] 4 s^{2}$ . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration $[\text{ar}] 4 s^{2} \; 3d^{1}$ and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the $ns^{2} \; (n-1) p^{1}$ and should be highlighted as well.

Answer from: Quest

the dissolution of polymer can be thermodynamically described in 2 steps.

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Determine the mass in grams of 2.71 x 10^21 atoms of arsenic if the mass of one mole is 74.92g...

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