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Ainat [17]
2 years ago
6

What does the large number in front of the molecule represent?

Chemistry
2 answers:
madam [21]2 years ago
4 0
A large number in front of a compound designates how many units there are of that compound. Parentheses can be used to designate a special structure, where other molecules are attached to the larger, complex molecule.
Len [333]2 years ago
4 0
It represents the Atomic mass
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Classify each element. Note that another term for main group is representative, another term for semimetal is metalloid, and the
NikAS [45]

The question is incomplete, here is the complete question:

Classify each element. Note that another term for main group is representative, another term for semi-metal is metalloid, and the inner transition metals are also called the lanthanide and actinide series.

Hf, Am, In, Ta, As, Se, Rn

<u>Answer:</u>

Hafnium and tantalum are transition elements.

Americium is a inner transition element.

Indium, Selenium and Radon are main group elements.

Arsenic is a metalloid.

<u>Explanation:</u>

Main group elements are the elements which belong to s block and p block. They are also known as representative elements.

S-block elements are defined as the elements whose last electron enters s-sub shell. The general electronic configuration of these elements is ns^{1-2}

P-block elements are defined as the elements whose last electron enters p-sub shell. The general electronic configuration of these elements is np^{1-6}

Metalloids are defined as the elements which show intermediate properties between metals and non-metals. There are 7 metalloids in the periodic table. They are: Boron, Silicon, germanium, Arsenic, Antimony, Tellurium and Polonium.

Transition elements are known as d-block elements. D block elements are defined as the elements whose last electron enters d sub shell. The general electronic configuration of these elements is [(n-1)d^{1-10}ns^{0-2}]

Inner transition elements are known as (f block) elements. (F block) elements are defined as the elements whose last electron enters (f subshell). The general electronic configuration of these elements is [(n-2)f^{1-14}(n-1)d^{0-1}ns^{2}]. They are also known as lanthanide and actinide series.

For the given elements:

  • <u>Option 1:</u> Hf

Hafnium is the 72nd element of the periodic table having electronic configuration of [Xe]4f^{14}5d^26s^2

As, the last electron is entering the d subshell, it is a transition element.

  • <u>Option 2:</u> Am

Americium is the 95th element of the periodic table having electronic configuration of [Rn]5f^{7}6d^07s^2

As, the last electron is entering the (f subshell), it is a inner transition element.

  • <u>Option 3:</u> In

Indium is the 49th element of the periodic table having electronic configuration of [Kr]5s^25p^1

As, the last electron is entering the p subshell, it is a main group element.

  • <u>Option 4:</u> Ta

Tantalum is the 73rd element of the periodic table having electronic configuration of [Xe]4f^{14}5d^56s^2

As, the last electron is entering the d subshell, it is a transition element.

  • <u>Option 5:</u> As

Arsenic is the 33rd element of the periodic table having electronic configuration of [Ar]4s^24p^3

As, the last electron is entering the p subshell, it is a main group element. It shows an intermediate property of metal and non-metal. Thus, it is a metalloid.

  • <u>Option 6:</u> Se

Selenium is the 34th element of the periodic table having electronic configuration of [Ar]4s^24p^4

As, the last electron is entering the p subshell, it is a main group element.

  • <u>Option 7:</u> Rn

Radon is the 86th element of the periodic table having electronic configuration of [Xe]4f^{14}5d^{10}6s^26p^6

As, the last electron is entering the p subshell, it is a main group element.

5 0
3 years ago
Which would be attracted most to a magnet?
Debora [2.8K]
Either iron or metal
8 0
3 years ago
If we use 18 moles of H2 how many moles of H2O do we make? Use this chemical equation: 6H2 + O2 → 3H2O
Ilya [14]
<h3>Answer:</h3>

9 mol H₂O

<h3>General Formulas and Concepts:</h3>

<u>Math</u>  

<u>Pre-Algebra</u>  

Order of Operations: BPEMDAS  

  1. Brackets
  2. Parenthesis
  3. Exponents
  4. Multiplication
  5. Division
  6. Addition
  7. Subtraction
  • Left to Right

<u>Chemistry</u>  

<u>Atomic Structure</u>  

  • Reading a Periodic Table
  • Moles
  • Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

<u>Stoichiometry</u>  

  • Using Dimensional Analysis
  • Analyzing reactions RxN
<h3>Explanation:</h3>

<u>Step 1: Define</u>

[RxN - Balanced] 6H₂ + O₂ → 3H₂O

[Given] 18 mol H₂

[Solve] mol H₂O

<u>Step 2: Identify Conversions</u>

[RxN] 6 mol H₂ → 3 mol H₂O

<u>Step 3: Stoich</u>

  1. [DA] Set up conversion:                                                                               \displaystyle 18 \ mol \ H_2(\frac{3 \ mol \ H_2O}{6 \ mol \ H_2})
  2. [DA] Simplify:                                                                                                 \displaystyle 18 \ mol \ H_2(\frac{1 \ mol \ H_2O}{2 \ mol \ H_2})
  3. [DA] Divide [Cancel out units]:                                                                     \displaystyle 9 \ mol \ H_2O
3 0
3 years ago
Read 2 more answers
The brain, spinal cord, and nerves are all major organs of the ___ system.
lyudmila [28]

Answer:

nervous system

Explanation:

nervous system

5 0
2 years ago
Read 2 more answers
Suppose a student started with 142.0 mg of trans-cinnamic acid, 412 mg of pyridinium tribromide, and 2.30 mL of glacial acetic a
nirvana33 [79]

Answer: Theoretical Yield = 0.2952 g

               Percentage Yield = 75.3%

Explanation:

Calculation of limiting reactant:

n-trans-cinnamic acid moles = (142mg/1000) / 148.16 = 9.584*10⁻⁴ mol

pyridium tribromide moles = (412mg/1000) / 319.82= 1.288*10⁻³ mol

  • n-trans-cinnamic acid is the limiting reactant

The molar ratio according to the equation mentioned is equals to 1:1

The brominated product moles is also = 9.584*10⁻⁴ mol

Theoretical yield = (9.584*10⁻⁴ mol) * (Mr of brominated product)

                             =  (9.584*10⁻⁴ mol) * (307.97) = 0.2952 g

Percentage Yield is : Actual Yield / Theoretical Yield = 0.2223/0.2952

                                                                                           = 75.3%

4 0
3 years ago
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