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3 years ago

Explain how the effects of nuclear charge and the increasing number of core electrons in an atom oppose each other.

1 answer:

3 0

The nulear charge is the number of protons.

As the number of protons increases, the nuclear charge grows ant thhe pulling electrostatic force between them and electrons also grows, given that the electrostatic force is proportional to the magnitude of the charges.

As the number of electrons grows, they occupy outer shelss (farther from the nucleus). And the outer electrons will feel not only the atraction of the protons from the nucleus, but the repulsion of the inner electrons.

Then, we see that the increase of nuclear charge is opposed by the increase of core electrons, and the outer (valence) electrons are not so tied to the nucleus as the core electrons are.

This is called shielding effect. A way to quantify the shielding effect is through the effective nuclear charge which is the number of protons (Z) less the number of core electrons.

The more the number of core shells the greater the shielding effect experience by electros in the outermost shells.

The shielding effect, explains why the valence eletrons are more easily removed from the atom than core electrons, and also explains some trends of the periodic table: variationof the size of the atoms in a row, the greater the shielding efect, the less the atraction force felt by the outermos electron, the farther they are and the larger the atom.

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Use the drop-down menus to complete each statement.

aleksley [76]

<u>Explanation:</u>

<u>1. Have many moons:</u>

Jupiter is the fifth planet from the Sun and the biggest in the Solar System and it has fifty-three moons which are confirmed and twenty-six provisional moons and totally it has seventy-nine moons and it is the only planet which has many moons.

<u>2. Have a rocky composition:</u>

The planets which have rocky composition are also called the terrestrial planets.
The planets which have rocky composition are listed below mercury, venus, earth, and mars and they are smaller in size.

<u>3. Revolve quickly around the Sun: </u>

Mercury is the quickest planet, which rushes around the sun at 47.87 km/s. And it revolves around the sun quickly.

<u> 4. Rotate quickly on their axes: </u>

The giant gas planets like Jupiter, Saturn, etc... spin more quickly on their axes than the other planets

6 0

3 years ago

Read 2 more answers

What amount (moles) is represented by each of these samples?

Zinaida [17]

<h3>Answer:</h3>

a) Moles of Caffeine = 1.0 × 10⁻⁴ mol

b) Moles of Ethanol = 4.5 × 10⁻³ mol

<h3>Solution:</h3>

Data Given:

Mass of Caffeine = 20 mg = 0.02 g

M.Mass of Caffeine = 194.19 g.mol⁻¹

Molecules of Ethanol = 2.72 × 10²¹

Calculate Moles of Caffeine as,

Moles = Mass ÷ M.Mass

Putting values,

Moles = 0.02 g ÷ 194.19 g.mol⁻¹

Moles = 1.0 × 10⁻⁴ mol

Calculate Moles of Ethanol as,

As we know one mole of any substance contains 6.022 × 10²³ particles (atoms, ions, molecules or formula units). This number is also called as Avogadro's Number.

The relation between Moles, Number of Particles and Avogadro's Number is given as,

Number of Moles = Number of Molecules ÷ 6.022 × 10²³

Putting values,

Number of Moles = 2.72 × 10²¹ Molecules ÷ 6.022 × 10²³

Number of Moles = 4.5 × 10⁻³ Moles

5 0

3 years ago

In the absence of sodium methoxide, the same alkyl bromide gives a different product. Draw an arrowpushing mechanism to account

hoa [83]

Answer:

See explanation below

Explanation:

The question is incomplete, cause you are not providing the structure. However, I found the question and it's attached in picture 1.

Now, according to this reaction and the product given, we can see that we have sustitution reaction. In the absence of sodium methoxide, the reaction it's no longer in basic medium, so the sustitution reaction that it's promoted here it's not an Sn2 reaction as part a), but instead a Sn1 reaction, and in this we can have the presence of carbocation. What happen here then?, well, the bromine leaves the molecule leaving a secondary carbocation there, but the neighbour carbon (The one in the cycle) has a more stable carbocation, so one atom of hydrogen from that carbon migrates to the carbon with the carbocation to stabilize that carbon, and the result is a tertiary carbocation. When this happens, the methanol can easily go there and form the product.

For question 6a, as it was stated before, the mechanism in that reaction is a Sn2, however, we can have conditions for an E2 reaction and form an alkene. This can be done, cause the extoxide can substract the atoms of hydrogens from either the carbon of the cycle or the terminal methyl of the molecule and will form two different products of elimination. The product formed in greater quantities will be the one where the negative charge is more stable, in this case, in the primary carbon of the methyl it's more stable there, so product 1 will be formed more (See picture 2)

For question 6b, same principle of 6a, when the hydrogen migrates to the 2nd carbocation to form a tertiary carbocation the methanol will promove an E1 reaction with the vecinal carbons and form two eliminations products. See picture 2 for mechanism of reaction.

3 0

3 years ago

Explain why calcium (Ca) has a greater atomic radius than magnesium (Mg).

g100num [7]

Answer:

Magnesium nucleus will attract the electrons more toward it and therefore, shrinking the size of the atom. Magnesium atom is smaller than Calcium atom because Calcium has more electron ( 20e− ) which will occupy more energy levels ( n=4 for Calcium versus n=3 for Magnesium)

8 0

3 years ago

The burning of a sample of propane

r-ruslan [8.4K]

Answer:

70.0°C

Explanation:

We are given;

Amount of heat generated by propane as 104.6 kJ or 104600 Joules
Mass of water is 500 g
Initial temperature as 20.0 ° C

We are required to determine the final temperature of water;

Taking the initial temperature is x°C

We know that the specific heat of water is 4.18 J/g°C

Quantity of heat = Mass × specific heat × change in temperature

In this case;

Change in temp =(x-20)° C

Therefore;

104600 J = 500 g × 4.18 J/g°C × (x-20)

104600 J = 2090x -41800

146400 = 2090 x

x = 70.0479

=70.0 °C

Thus, the final temperature of water is 70.0°C

7 0

3 years ago