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2 years ago

An element with the electron configuration: [noble gas] ns2 (n - 1)d10 np3 has how many_____________ valence electrons.

Chemistry

1 answer:

Marina86 [1]2 years ago

5 0

Answer:

The correct option is e. 5

Explanation:

An element with the electron configuration [noble gas] ns² (n - 1)d¹⁰ np³ belongs to the nitrogen group element - group 15 - in a period higher than 2. The element could be As, Sb or Bi. For example, arsenic (As) has the electron configuration [Ne] 4s² 3d¹⁰ 4p³.

The valence electrons are those in the highest energy level, in a s or p sublevel. For the elements with the general electron configuration [noble gas] ns² (n - 1)d¹⁰ np³ has 5 valence electrons: 2 electrons in a s sublevel and 3 electrons in a p sublevel. The electrons in the d orbital are in a lowest energy level (n-1).

Therefore, the correct option is e. 5.

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there are 125 lima beans 56 garbanzo beans 39 kidney beans and 144 green peas in a container. find the percent by number of gree

Sauron [17]

39.6% of the beans are green beans

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2 years ago

1. Calculate the energy of a photon with a frequency of 3x1015 Hz.<br> ?????

Afina-wow [57]

Answer:

1.99 x 10⁻¹⁸J

Explanation:

Given parameters:

Frequency of the wave = 3 x 10¹⁵Hz

Unknown:

Energy of the photon = ?

Solution:

To solve this problem, we use the expression below;

E = hf

Where E is the energy, h is the Planck's constant and f is the frequency

Now insert the parameters and solve for E;

E = 6.63 x 10⁻³⁴ x 3 x 10¹⁵ = 19.9 x 10⁻¹⁹J or 1.99 x 10⁻¹⁸J

6 0

2 years ago

What is a mole?

fredd [130]

Answer:

Explanation:

One mole is the amount of substance that contain the Avogadro number which is equal to 6.022×10^23 atom, molecules or ions.

7 0

2 years ago

The molar mass is determined by measuring the freezing point depression of an aqueous solution. A freezing point of -5.20°C is r

Dima020 [189]

Answer:

The empirical formula is C2H4O3

The molecular formula is C4H8O6

The molar mass is 152 g/mol

Explanation:

The complete question is: An unknown compound contains only carbon, hydrogen, and oxygen. Combustion analysis of the compound gives mass percents of 31.57% C and 5.30% H. The molar mass is determined by measuring the freezing-point depression of an aqueous solution. A freezing point of -5.20°C is recorded for a solution made by dissolving 10.56 g of the compound in 25.0 g water. Determine the empirical formula, molar mass, and molecular formula of the compound. Assume that the compound is a nonelectrolyte.

Step 1: Data given

Mass % of Carbon = 31.57 %

Mass % of H = 5.30 %

Freezing point = -5.20 °C

10.56 grams of the compound dissolved in 25.0 grams of water

Kf water = 1.86 °C kg/mol

Step 2: Calculate moles of Carbon

Suppose 31.57% = 31.57 grams

moles C = mass C / Molar mass C

moles C = 31.57 grams / 12.0 g/mol = 2.63 moles

Step 3: Calculate moles of Hydrogen:

Moles H = 5.30 grams / 1.01 g/mol

moles H = 5.25 moles

Step 4: Calculate moles of Oxygen

Moles O = ( 100 - 31.57 - 5.30) / 16 g/mol

Moles O = 3.95 moles

Step 5: We divide by the smallest number of moles

C: 2.63 / 2.63 = 1 → 2

H: 5.25/2.63 = 2 → 4

O: 3.95/ 2.63 = 1.5 → 3

The empirical formula is C2H4O3

The molar mass of the empirical formula = 76 g/mol

Step 6: Calculate moles solute

Freezing point depression = 5.20 °C = m * 1.86

m = 5.20 / 1.86

m = 2.80 molal = 2.80 moles / kg

2.80 molal * 0.025 kg = 0.07 moles

Step 7: Calculate molar mass

Molar mass = mass / moles

Molar mass = 10.56 grams / 0.07 moles

Molar mass = 151 g/mol

Step 8: Calculate molecular formula

151 / 76 ≈ 2

We have to multiply the empirical formula by 2

2*(C2H4O3) = C4H8O6

The molecular formula is C4H8O6

The molar mass is 152 g/mol

6 0

2 years ago

Identify the double displacement reaction. 3Pb 2h 3PO 4 ⟶ 3H 2 Pb 3(PO 4) 2 2NO 2 ⟶ 2O 2 N 2 2NaBr Ca(OH) 2 ⟶ CaBr 2 2NaOH 2NH 3

IRISSAK [1]

Reaction 3 is the double displacement reaction.

Double displacement reaction occurs when the negatively and the positively charged ions of the compounds interchange their position when the new compound in the product is formed.

<h3>Which is a double displacement reaction?</h3>

In the <u>first reaction</u>, the element lead (Pb) is not an ion and no exchange of the cations or the anions occurs hence it is not a double displacement reaction.

In the <u>second reaction</u>, one compound is getting split into two new compounds and is a decomposition reaction.

In the <u>third reaction</u>, $\rm Br^{-}$ in $\rm 2NaBr$ and $\rm (OH)_{2}$ in $\rm Ca(OH)_{2}$ are anions and cations and exchanges their places to produce two new compounds $\rm CaBr_{2} + 2NaOH.$

In the <u>fourth reaction</u>, a single compound is generated as the result of the combination reaction and hence, it is not the double displacement reaction.

Therefore, $\rm 2NaBr + Ca(OH)_{2} \rightarrow CaBr_{2} + 2NaOH$ is the double displacement reaction.

Learn more about double displacement reaction here:

brainly.com/question/10091171

3 0

1 year ago