Which of the following is the final stage of a low mass star? * 1 point

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

Kipish [7]

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.

3 0

3 years ago

How many grams of sodium nitrate (NaNO2) will dissolve in 100g of water at 20°C?

inn [45]

88g ( so sorry if this isn’t correct )

8 0

3 years ago

Identify the single displacement reaction. 2H 2 + O 2 ⟶ 2H 2O Al 2S 3 ⟶ 2Al + 3S Cl 2 + 2KBr ⟶ 2KCl + Br 2 C 4H 12 + 7O 2 ⟶ 6H 2

ozzi

Answer: $Cl_2+2KBr\rightarrow 2KCl+Br_2$

Explanation:

A single displacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution. Thus one element should be different from another element.

$Cl_2+2KBr\rightarrow 2KCl+Br_2$

Synthesis reaction is defined as the reaction where substances combine in their elemental state to form a single compound. $2H_2+O_2\rightarrow 2H_2O$

Decomposition reaction is defined as the reaction where a single substance breaks down into two or more simpler substances.

$Al_2S_3\rightarrow 2Al+3S$

Combustion is a type of chemical reaction in which hydrocarbons burn in the presence of oxygen to form carbon dioxide and water along with heat.

$C_4H_{12}+7O_2\rightarrow 6H_2O+4CO_2$

6 0

4 years ago

Rhodium crystallizes in a face-centered cubic unit cell. The radius of a rhodium atom is 135 pm. Determine the density of rhodiu

Deffense [45]

Answer:

Density of unit cell ( rhodium) = 12.279 g/cm³

Explanation:

Given that:

The radius (r) of a rhodium atom = 135 pm

The atomic mass of rhodium = 102.90 amu

For a face-centered cubic unit cell,

$r = \dfrac{a}{2\sqrt{2}}$

where;

a = edge length.

Making "a" the subject of the formula:

$a = 2 \sqrt{2} \times r$

$a = 2 \times 1.414 \times 135 \ pm$

a = 381.8 pm

to cm, we get:

a = 381.8 × 10⁻¹⁰ cm

However, recall that:

$density \ of \ unit \ cell = \dfrac{mass \ of \ unit \ cell}{volume \ of \unit \ cell}$

where;

mass of unit cell = mass of atom × numbers of atoms per unit cell

Also;

$mass\ of\ atom =\dfrac{ atomic \ mass}{Avogadro \ number}$

$mass\ of\ atom =\dfrac{ 102.9}{6.023 \times 10^{23}}$

Recall also that number of atoms in a unit cell for a face-centered cubic = 4

So;

$mass \ of \ unit \ cell= \dfrac{102.90}{6.023 \times 10^{23}}\times 4$

mass of unit cell = 6.83380375 × 10⁻²² g

$Density \ of \ unit \ cell = \dfrac{6.83380375 \times 10^{-22}}{(381.8\times 10^{-10})^3}$

Density of unit cell ( rhodium) = 12.279 g/cm³

3 0

3 years ago

Which of the following is an acceptable IUPAC name?(A) 3,6-dimethylheptane (B) 2-ethyl-3-methylheptane (C) 5-methyl-3-ethylhepta

bearhunter [10]

Answer:

D) 4-ethyl-4-methylheptane

Explanation:

The rules for naming of alkanes with substituents.

1. The carbon chain with the maximum number of carbon atoms must be selected as a parent chain.

2.Numbering should be done in such a way that each substituent gets the least number.

3. Substituents whose name comes before the another substituents's name in the English alphabet is written first.

4. Substituents are written first with their location in the chain and the name of the parent chain is done. Numbers are separated from numbers by comma and numbers are separated from letters by using hyphen.

Considering (a) 3,6-dimethylheptane

Violation of Rule - 2 mentioned above

The numbering of the parent chain is not done in a right way. Numbering must be done such that each substituent gets the least number. So, The correct name is 2,5-dimethylheptane

Considering (b) 2-ethyl-3-methylheptane

Violation of Rule - 1 mentioned above.

The carbon chain with the maximum number of carbon atoms must be selected as a parent chain. The parent chain selected is of 7 carbon atoms but the parent chain is of 8 carbon atoms. So, The correct name is 3,4-dimethyloctane

Considering (c) 5-methyl-3-ethylheptane

Violation of Rule - 3 mentioned above.

'e' comes before 'm' . So, ethyl- is written first than methyl- . So, The correct name is 3,6-dimethyloctane

Considering (d) 4-ethyl-4-methylheptane

This is a IUPAC name and following all the rules mentioned above.

3 0

3 years ago