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Goshia [24]
3 years ago
9

Cite two important quantum-mechanical concepts associated with the Bohr model of the atom.(b) Cite two important additional refi

nements that resulted from the wave-mechanical atomic model.
Chemistry
2 answers:
Alenkinab [10]3 years ago
8 0

Answer: Bohr postulated that electronic energy levels are quantized. Secondly, a photon of light of a particular frequency is emitted when electrons move from a higher to a lower energy levels.

Explanation:

The Bohr model of the atom is the immediate predecessor of the wave mechanical model of the atom. The wave mechanical model refined the Bohr's model by treating the electron as a wave having a wave function psi. The wave function describes the identity of the electron. From Heisenberg uncertainty principle, the position of a particle cannot be accurately and precisely measured. Hence the wave mechanical model added that electrons are not localized in orbits according to Bohr's model but the integral of psi squared dx gives the probability of finding the electron within a given space.

Alekssandra [29.7K]3 years ago
4 0

Answer A: The two important quantum-mechanical concepts associated with the Bohr model includes:

1) that electrons are particles moving in separate or individual orbitals.

2) electron energy is quantised into shells.

Explanation:

Neil- Bohr model structure of atoms shows that electrons of atoms appears in orbits of different energy revolving around the nucleus. He also described how these electrons can have one energy level at a time, that is, the electrons are quantised in shells.

Answer B: the two important refinements resulting from the wave mechanical atomic model includes:

1) that electron position is described in terms of a probability distribution.

2) electron energy is quantised into both shells and subshell.a and each electron is characterised by four quantum numbers.

Explanation: Wave mechanical atomic model was created by the Physicist Erwin Schrödinger. He refined the work of Bohr by using mathematical equations to describe the likelihood of finding an electron in a certain position. Rather than defining the exact path of an electron like in Bohr method, he predicted the odds of the location of the electrons.

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Answer:

  • <em>He realized that some elements had not been discovered.</em>

Explanation:

Some scientists that tried to arrange the list of elements known before Mendeleev include Antoine Lavoisier, Johann Döbereiner, Alexandre Béguyer de Chancourtois, John Newlands, and Julius Lothar Meyer.

<em>Dimitri Mendeleev</em> was so succesful that he is recognized as the most important in such work.

Mendeleev by writing the properties of the elements on cards elaborated by him, and "playing" trying to order them, realized that, some properties regularly (periodically) repeated.

The elements were sorted in increasing atomic weight (which is not the actual order in the periodic table), but when an element did not meet the pattern discovered, he moved it to a position were its properties fitted.

The amazing creativity of Mendeleev led him to leave blanks for what he thought were places that should be occupied by elements yet undiscovered. More amazing is that he was able to predict the properties of some of those elements.

When years after some of the elements were discovered, the genius of Mendeleev was proven because the "new" elements had the properties predicted by him.

7 0
3 years ago
If a car a have mileage rating of 49miles per gallon. If the car makes a trip of 279 miles, how many gallons of gasoline will be
BartSMP [9]
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4 0
4 years ago
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A chemist adds 26.5g of ammonium chloride to 10g of sodium hydroxide, which follows the reaction below. Assuming the reaction go
4vir4ik [10]

Answer :  The amount of reactant left in excess is 13.1075 grams.

Explanation : Given,

Mass of NH_4Cl = 26.5 g

Mass of NaOH = 10 g

Molar mass of NH_4Cl = 53.5 g/mole

Molar mass of NaOH = 40 g/mole

First we have to calculate the moles of NH_4Cl and NaOH.

\text{Moles of }NH_4Cl=\frac{\text{Mass of }NH_4Cl}{\text{Molar mass of }NH_4Cl}=\frac{26.5g}{53.5g/mole}=0.495moles

\text{Moles of }NaOH=\frac{\text{Mass of }NaOH}{\text{Molar mass of }NaOH}=\frac{10g}{40g/mole}=0.25moles

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

NH_4Cl+NaOH\rightarrow NH_4OH+NaCl

From the balanced reaction we conclude that

As, 1 mole of NaOH react with 1 mole of NH_4Cl

So, 0.25 moles of NaOH react with 0.25 moles of NH_4Cl

From this we conclude that, NH_4Cl is an excess reagent because the given moles are greater than the required moles and NaOH is a limiting reagent and it limits the formation of product.

Moles of remaining excess reactant = 0.495 - 0.25 = 0.245 moles

Now we have to calculate the mass of NH_4Cl.

\text{Mass of }NH_4Cl=\text{Moles of }NH_4Cl\times \text{Molar mass of }NH_4Cl

\text{Mass of }NH_4Cl=(0.245mole)\times (53.5g/mole)=13.1075g

Therefore, the amount of reactant left in excess is 13.1075 grams.

5 0
3 years ago
A sample of propane (C3H8) is placed in a closed vessel together with an amount of O2 that is 3 times the amount needed to compl
Aneli [31]

Answer:

final mole fraction of O₂ = 58.84% , CO₂ = 17.64% , H₂O = 23.52% .

final partial pressure of O₂ = 2.942 atm , CO₂ = 0.882 atm , H₂O = 1.176 atm .

Explanation:

Assuming that propane is present as a gas , and also that the combustion is complete:

C₃H₈ + 5 O₂ → 3 CO₂ + 4 H₂O

then taking as a reference propane sample= 1 mol , then

initial moles of O₂ = 3* 5 moles = 15 moles

final moles of O₂= 3* 5 moles - 5 moles = 10 moles

final moles of CO₂ = 3 moles

final moles of H₂O = 4 moles

total number of moles = 10 + 3 + 4 = 17 moles

final mole fraction of O₂ = 10/17 = 0.5884 = 58.84%

final mole fraction of  CO₂ = 3/17 = 0.1764 = 17.64%

final mole fraction of  H₂O = 4/17 = 0.2352 = 23.52%

From Dalton's law for ideal gases , the partial pressure p=P*x then

final partial pressure of O₂ = 5 atm * 10/17 = 2.942 atm

final partial pressure of CO₂ = 5 atm * 3/17 = 0.882 atm

final partial pressure of H₂O = 5 atm * 1/17 = 1.176 atm

4 0
3 years ago
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