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3 years ago

The electron configuration for an atom is 1s 2s 2p2. How many electrons does the atom have?

Chemistry

1 answer:

taurus [48]3 years ago

7 0

Answer:

Four

Step-by-step explanation:

The <em>superscripts</em> in an electron configuration tell us how many electrons are in a subshell.

If the electron configuration is 1s¹ 2s¹2p², the total number of electrons is

1 + 1 + 2 = 4

The atom contains four electrons.

<em>Note</em>: this atom is in an <em>excited state</em>, because the 1s and 2s subshells can each hold one more electron.

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PLEASE HELP ME ASAP ILL MARK U AS BRILLIANT

faust18 [17]

Answer:

19 D

20 C

21 B

22 A

23 A

24 A

Explanation:

See the periodic table

6 0

3 years ago

How many moles do you have in 37.3 g of Co(CrO4)3

shutvik [7]

Answer:

0.0917 mol Co(CrO₄)₃

General Formulas and Concepts:

<u>Chemistry - Atomic Structure</u>

Reading a Periodic Table
Using Dimensional Analysis

Explanation:

<u>Step 1: Define</u>

37.3 g Co(CrO₄)₃

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

Molar Mass of Co - 58.93 g/mol

Molar Mass of Cr - 52.00 g/mol

Molar Mass of O - 16.00 g/mol

Molar Mass of Co(CrO₄)₃ - 58.93 + 3(52.00) + 12(16.00) = 406.93 g/mol

<u>Step 3: Convert</u>

<u /> $37.3 \ g \ Co(CrO_4)_3(\frac{1 \ mol \ Co(CrO_4)_3}{406.93 \ g \ Co(CrO_4)_3} )$ = 0.091662 mol Co(CrO₄)₃

<u>Step 4: Check</u>

<em>We are given 3 sig figs. Follow sig fig rules and round.</em>

0.091662 mol Co(CrO₄)₃ ≈ 0.0917 mol Co(CrO₄)₃

8 0

2 years ago

Why is it important that scientific knowledge changes?

aleksandrvk [35]

Answer:Scientific knowledge can change because it is often examined and re-examined by new investigations and scientific argumentation. Because of these frequent examinations, scientific knowledge becomes stronger, leading to its durability. ... B: Scientific knowledge is durable and robust, but open to change.

3 0

3 years ago

Read 2 more answers

Calculate the equilibrium constant of the reaction below if the pressures are 1.0atm, 2.0 atm, and 1.0 atm respectively. PCl3 +

Makovka662 [10]

Answer:

K = 0.5

Explanation:

Based on the reaction:

PCl₃ + Cl₂ ⇄ PCl₅

The equilibrium constant, K, is defined as:

K = P PCl₅ / P PCl₃ * P Cl₂

<em>Where P represent the pressure at the equilibrium for each one of the gases involved in the equilibrium.</em>

<em />

As:

P PCl₅ = 1.0atm

P PCl₃ = 1.0atm

P Cl₂ = 2.0atm

K = 1.0atm / 1.0atm * 2.0atm

7 0

2 years ago

28) Consider a 21.0 mL sample of pure lemon juice with a citric acid (H3C6H5O7) concentration of 0.30M. a. How many moles of cir

Damm [24]

<h3>#a. Answer:</h3>

0.0063 mole

<h3>Solution and explanation:</h3>

We are given 21.0 mL citric acid with a concentration of 0.30 M

Part a requires we calculate the number of moles of citric acid.

We need to know how to calculate the concentration of a solution;

Concentration or molarity = Number of moles ÷ Volume of the solution

Thus;

Number of moles = Concentration × Volume

Hence;

Moles = 0.30 M × 0.021 L

= 0.0063 mole

<h3>#b. Answer</h3>

1.21 g citric acid

<h3>Solution</h3>

Part B

We are required to calculate the mass of citric acid in the sample

Number of moles of a compound is calculated by dividing its mass by its molar mass.

Molar mass of Citric acid = 192.124 g/mol

Moles of citric acid = 0.0063 mole

But; Mass = Number of moles × Molar mass

Mass of citric acid = 0.0063 mol × 192.124 g/mol

= 1.21 g citric acid

<h3>#c. Answer</h3>

4.167 mL

<h3>Solution:</h3>

Part C

We are required to determine the initial volume before dilution;

We have;

Initial concentration (M1) = 0.30 M

Final volume (V2) = 250 mL or 0.25 L

Final concentration (M2) = 0.0050 M

Using the dilution formula we can get the initial volume;

Therefore, since; M1V1 =M2V2

V1 = M2V2÷M1

= (0.0050 × 0.25)÷ 0.30

= 0.004167 L or

= 4.167 mL

Therefore, the initial volume of the solution is 4.167 mL

8 0

3 years ago