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3 years ago

Write the electron configuration for sodium.

Chemistry

1 answer:

Dafna11 [192]3 years ago

4 0

Answer:

1s^2..2s^2..2p^6..3s^1

Explanation:

Since sodium has 11 electrons...its electron configuration is...;

1s^2..2s^2..2p^6..3s^1

;The powers of the energy levels(i.e s,p,d) should all add up to the number of electrons in an atom

*.When writing...please do not separate them.

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Most metals are in the liquid state at room temperature.

Alexxandr [17]

That statement is False.

Most metals are in the solid state at room temperature. The only metal that is in liquid state in the room temperature is Mercury, (Hg)

7 0

3 years ago

1. Calculate the heat change associated with cooling a 350.0 g aluminum bar from

Amanda [17]

Answer:

14175 j heat released.

Explanation:

Given data:

Mass of aluminium = 350.0 g

Initial temperature = 70.0°C

Final temperature = 25.0°C

Specific heat capacity of Aluminium = 0.9 j/g.°C

Heat changed = ?

Solution:

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

Heat change:

ΔT = Final temperature - initial temperature

ΔT = 25.0°C - 70°C

ΔT = -45°C

Q = m.c. ΔT

Q = 350 g × 0.9 j/g.°C × -45°C

Q = -14175 j

7 0

3 years ago

How many valence electrons would there be for the element with the following orbital diagram?

Svetach [21]

Answer:

Explanation:

The p orbital needs 2 more electrons.

8 0

3 years ago

Chromium(III) oxide can be prepared by heating chromium(IV) oxide in vacuo at high temperature: 4Cr02 —2Cr2O3 +02 The reaction o

kkurt [141]

Answer: The theoretical yield and percent yield of chromium (III) oxide is 434.72 grams and 92.6 % respectively.

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

Given mass of $CrO_2$ = 480.1 g

Molar mass of $CrO_2$ = 84 g/mol

Putting values in equation 1, we get:

$\text{Moles of }CrO_2=\frac{480.1g}{84g/mol}=5.72mol$

For the given chemical equation:

$4CrO_2\rightarrow 2Cr_2O_3+O_2$

By Stoichiometry of the reaction:

4 moles of $CrO_2$ produces 2 moles of chromium (III) oxide

So, 5.72 moles of $CrO_2$ will produce = $\frac{2}{4}\times 5.72=2.86mol$ of chromium (III) oxide

Now, calculating the mass of chromium (III) oxide from equation 1, we get:

Molar mass of chromium (III) oxide = 152 g/mol

Moles of chromium (III) oxide = 2.86 moles

Putting values in equation 1, we get:

$2.86mol=\frac{\text{Mass of chromium (III) oxide}}{152g/mol}\\\\\text{Mass of chromium (III) oxide}=(2.86mol\times 152g/mol)=434.72g$

To calculate the percentage yield of chromium (III) oxide, we use the equation:

$\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100$

Experimental yield of chromium (III) oxide = 402.4 g

Theoretical yield of chromium (III) oxide = 434.72 g

Putting values in above equation, we get:

$\%\text{ yield of chromium (III) oxide}=\frac{402.4g}{434.72g}\times 100\\\\\% \text{yield of chromium (III) oxide}=\%$

Hence, the theoretical yield and percent yield of chromium (III) oxide is 434.72 grams and 92.6 % respectively.

7 0

3 years ago

Select ALL correct answers. The contact force is caused by: A. Atoms randomly crashing into each other B. The charged particles

Inessa [10]

Answer:

A. Atoms randomly crashing into each other

E. The force of one object pushing against the force of another object.

Explanation:

Forces can be classified into two categories based upon the the mode of transfer or application:

1. Contact forces

2. Non-contact forces

Contact forces are the ones which require the physical contact of the matter to get transferred and tend to create the affect. Whereas non-contact forces have the field property which transfers the affect of force from one point to another without any physical contact of the matter or the medium.

Atoms crashing onto each other have some mass and velocity which upon collision impacts the other atoms exerts a contact force.
The interaction between the charged particles due to their charges is always due to the electric field be it electron or proton, be it within an atom or out of an atom.
The force between any two objects pushing or pulling each other is also possible only due to contact.

6 0

3 years ago