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2 years ago

What is the number of electrons in an atom of scandium

1 answer:

4 0

The nuclear composition and electron configuration of an atom of Scandium 45 and the atomic number is 21 the most common isotype of this element is that nuclear consists of 21 protons and 24 neutrons Scandium is a transition metal group 3 period and the d-block of a periodic table

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Atoms with a low electronegativity,like lithium,have a weak attractive force for electrons because

Murrr4er [49]

Answer:

they're close to filling their outer shell, fulfilling the octet rule

Explanation:

3 0

3 years ago

Three elements are represented by the letters A, B, and C. the three elements have the same number of valence electrons. Element

AfilCa [17]

Answer:
A- beryllium
B- calcium
C- magnesium

Explanation
NOTE: all element in group 2 have 2 balance electrons

First let’s start with B- number of electrons= number of protons which is equal to the atomic number. therefore, the answer is calcium as it’s atomic number is 20

C- magnesium will have three energy levels considering it has 12 electrons (2,8,2).

A- beryllium is the lightest one in group 2 as it has the atomic mass of 9.0122.

3 0

3 years ago

A backpacker carries 2.7 L of white gas as fuel for her stove.How many pounds does the fuel add to her load? Assume the density

Zepler [3.9K]

2.7 L in cm³ :

2.7 * 1000 = 2700 cm³

Weight = Volume * Density

2700 * 0.79 = 2133 g

1 Ibs = 453.59 g

2133 / 453.59 = 4.70 Ibs

hope this helps!

6 0

3 years ago

At 25°C, K = 0.090 for the following reaction. H2O(g) + Cl2O(g) equilibrium reaction arrow 2 HOCl(g) Calculate the concentration

wlad13 [49]

Answer:

[HOCl] = 0.00909 mol/liter

[H₂O] = 0.03901 mol/liter

[Cl₂O] = 0.02351 mol/liter

Explanation:

1. Chemical reaction:

$H_2O(g)+Cl_2O(g)\rightleftharpoons 2 HOCl(g)$

2. Initial concentrations:

i) 1.3 g H₂O

Number of moles = 1.3g / (18.015g/mol) = 0.07216 mol

Molarity, M = 0.07216 mol / 1.5 liter = 0.0481 mol/liter

ii) 2.2 g Cl₂O

Number of moles = 2.2 g/ (67.45 g/mol) = 0.0326 mol

Molarity = 0.0326mol / 1.5 liter = 0.0217 mol/liter

3. ICE (Initial, Change, Equilibrium) table

$H_2O(g)+Cl_2O(g)\rightleftharpoons 2 HOCl(g)$

I 0.0481 0.0326 0

C -x -x +x

E 0.0481-x 0.0326-x x

4. Equilibrium expression

$K_c=\dfrac{[HOCl]^2}{[H_2O].[Cl_2O]}$

$0.09=\dfrac{x^2}{(0.0481-x)(0.0326-x)}$

5. Solve:

$x^2=0.09(x-0.0481)(x-0.0326)\\\\0.91x^2+0.007263x-0.000141125=0$

Use the quadatic formula:

$x=\dfrac{-0.007263\pm \sqrt{(0.007263)^2-4(0.91)(-0.000141125)}}{2(0.91)}$

The positive result is x = 0.00909

Thus the concentrations are:

[HOCl] = 0.00909 mol/liter

[H₂O] = 0.0481 - 0.00909 = 0.03901 mol/liter

[Cl₂O] = 0.0326 - 0.00909 = 0.02351 mol/liter

3 0

3 years ago

a cylinder with a movable piston contains 250 cm3 air at 10°C. if the pressure is kept constant, at what temperature would you e

soldi70 [24.7K]

Answer:

T₂ = 169.89 K

Explanation:

Given data:

Initial volume = 250 cm³

Initial temperature = 10°C (10+273.15 K = 283.15 K)

Final temperature = ?

Final volume = 150 cm³

Solution:

The given problem will be solve through the Charles Law.

According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure.

Mathematical expression:

V₁/T₁ = V₂/T₂

V₁ = Initial volume

T₁ = Initial temperature

V₂ = Final volume

T₂ = Final temperature

Now we will put the values in formula.

V₁/T₁ = V₂/T₂

T₂ = T₁V₂/V₁

T₂ = 283.15 K × 150 cm³ / 250 cm³

T₂ = 42472.5 K. cm³ / 250 cm³

T₂ = 169.89 K

5 0

3 years ago