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3 years ago

How were atomic models developed when no one had seen an atom?

1 answer:

4 0

Atomic models were developed through indirect observation even though no one had seen an atom. There were many experiments of which I know nothing about, but in the end the scientists managed to come up with a formula and various models to describe atoms.

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Which of the following isoelectronic series is correctly ranked from largest ionic radius to smallest ionic radius? 1. N 3−, O 2

love history [14]

Answer:

Option 1: N⁻³ > O⁻² > F⁻ > Na⁺ > Mg⁺²

Explanation:

Ionic radius is the radius of an atom´s ion in ionic crystal structure. In an ion that lose an electron, to form a cation, the radius of the ion gets smaller, because the repulsion between electrons decrease because fewer electrons are present. Conversely, adding on electron to a neutral atom, to form an anion, causes electron - electron repulsions to increase, so the size of the radius of the ion gets bigger.

Isoelectronic species are ions or elements that have the same number of electrons in their electronic shells but have different overall charges, because of their different atomic numbers.

In a isolelectronic series (same number of electrons), the increase of the positive charge (given by the number of protons in the nucleus), will cause a decrease in radius beacuse the greater electrostatic attraction between the electrons and the nucleus. Consequently, the ion with the greatest nuclear charge will have the smallest ionic radius and the ion with the smallest nulear charge will have the largest ionic radius.

We will use this principle to solve our problem.

In our case, the given ions are:

N⁻³ : Z = 7, e⁻ = 10
O⁻²: Z= 8, e⁻ =10
F⁻: Z = 9, e⁻ = 10
Na⁺: Z= 11, e⁻ = 10
Mg⁺²: Z=12, e⁻ =10

where Z= number of protons, and e⁻ = number of electrons.

Hence the decreasing order of ionic radius is:

N⁻³ > O⁻² > F⁻ > Na⁺ > Mg⁺²

Have a nice day!

4 0

3 years ago

A monatomic ideal gas expands slowly to twice its original volume, doing 340 JJ of work in the process. Part APart complete Find

Dafna1 [17]

Answer:

A) if the system is isothermal then all the heat added to the system will be used to do work (since none is used to raise the temperature of the gas). The heat added will be equal to the work done = 340 J

B) change in internal energy of the system of the process is isothermal will be zero, since there is no rise in temperature.

C) an adiabatic process is one involving no heat loss or gain through the system, Therefore heat gain will be zero

D) if the process is adiabatic then there is no heat loss or gain through the system and hence there is no change in temperature. Change in internal energy will be zero

E) if the process is isobaric then, there is no work done and the total heat to the system is equal zero

F) if there is no work done, and no heat added, then the internal energy will be equal zero.

4 0

3 years ago

Which of these planets has the coldest surface temperature?

lianna [129]

Neptune planet has the coldest surface temperature

Explanation:

With temperatures falling to -218°C in Neptune’s upper atmosphere, the planet is one of the coolest in our Solar System. Neptune is the most faraway planet from the sun. Astronomers have speculated that Neptune's huge internal temperature and the transfer of heat between the core and outer layers might be the cause why Neptune isn't significantly more chill than Uranus.

Pressures in this area range between 1 and 5 bars and the temperature reaches a high of 72 K. At this temperature, states are becoming for methane to condense, and clouds of ammonia and hydrogen sulfide are thought to form. At its core, Neptune reaches temperatures of up to 7273 K which is equivalent to the surface of the sun.

3 0

3 years ago

Read 2 more answers

In three to five sentences, identify two components of the control subsystem of a vehicle, and use them

tekilochka [14]

Answer:

The control subsystem of a vehicle can have several parts. Two examples are the braking and steering wheel. If the subsystem were to malfunction, driving could potentially be dangerous due to the fact that the car could go out of control and make an impact on another car. For example, if the brakes aren’t working you cannot stop the vehicle in time and if the steering wheels went you can’t move the vehicle.

3 0

2 years ago

Solid Magnesium reacts with a Iron (II) Chloride solution ->

photoshop1234 [79]

Answer:

Magnesium + iron chloride → iron + magnesium chloride

Explanation:

It is the single replacement reaction.

Single replacement:

It is the reaction in which one elements replace the other element in compound.

AB + C → AC + B

Molecular equation:

Magnesium + iron chloride → iron + magnesium chloride

Chemical equation:

Mg(s) + FeCl₂(aq) → MgCl₂(aq) + Fe(s)

Ionic equation:

Mg(s) + Fe²⁺(aq) + 2Cl⁻(aq) → Mg²⁺(aq) + 2Cl⁻(aq) + Fe(s)

Net ionic equation:

Mg(s) + Fe²⁺(aq) → Fe(s) + Mg²⁺(aq)

5 0

3 years ago