Why have scientists changed their ideas on the model of the atom?

Answers

Answer 1

Answer:

Scientists used the model to make predictions. Sometimes the result of the experiments were a surprise and they did not fit with the existing model!


Related Questions

let's say these four solutions have the same concentration, which one has the highest freezing point?​

a) calcium chloride
b) glucose
c) sodium chloride
d) ammonium chloride​

Answers

Answer:

c) Sodium chloride

22. A mixture of gases contains 1.0 atm of neon, 2.0 atm
of Argon, and 6.0 atm of xenon. What is the total pressure
in the container?

Answers

The total pressure of the mixture of the nobles gases in the container is determined as 9 atm.

What is total pressure of the gases?

The total pressure of the gasses is equal to the total pressure of the container.

Pt = P1 + P2 + P3

Pt = 1 atm (neon) + 2 atm (Argon) + 6 atm( xenon)

Pt = 9 atm

Thus, the total pressure of the mixture of the nobles gases in the container is determined as 9 atm.

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compare fission and fusions.

Answers

Both Fission and Fusion both have to do with the nuclei. Also, Both fission and fusion are nuclear reactions that produce energy.

Arrhenius theorized that an acid is a chemical compound that

Answers

Answer:

increases the H + ion concentration in aqueous solution

Explanation:

An Arrhenius base is a compound that increases the OH − ion concentration in aqueous solution. Arrhenius theory, theory, introduced in 1887 by the Swedish scientist Svante Arrhenius, that acids are substances that dissociate in water to yield electrically charged atoms or molecules, called ions, one of which is a hydrogen ion (H+), and that bases ionize in water to yield hydroxide ions (OH−). Arrhenius Definition of acids. An acid is a substance that dissociates in water to produce H+ (hydrogen ions) Arrhenius Definition of strong acids. A strong acid is a substance that fully dissociates in water to give hydrogen ions. Arrhenius Definition of weak acids.

Type the correct answer in the box. given: cac2 n2 → cacn2 c in this chemical reaction, how many grams of n2 must be consumed to produce 265 grams of cacn2? express your answer to three significant figures. the reaction requires grams of n2.

Answers

The amount, in grams, of [tex]N_2[/tex] that will be consumed to produce 265 grams of [tex]CaCN_2[/tex] will be 80.61 grams

Stoichiometric calculation

From the equation of the reaction:

[tex]CaC_2 + N_2 --- > CaCN_2 + C[/tex]

The mole ratio of  [tex]N_2[/tex] consumed to   [tex]CaCN_2[/tex] produced is 1:1.

Mole of 265 grams of  [tex]CaCN_2[/tex] = 265/92.11 = 2.88 moles

Equivalent moles of  [tex]N_2[/tex] = 2.88 moles

Mass of 2.88 moles  [tex]N_2[/tex] = 2.88 x 28.02 = 80.61 grams

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How can you tell if a substance is an acid or base?

Answers

Answer:

To determine whether a substance is an acid or a base, count the hydrogens on each substance before and after the reaction. If the number of hydrogens has decreased that substance is the acid (donates hydrogen ions). If the number of hydrogens has increased that substance is the base (accepts hydrogen ions

what is the mass in grams for 7.14x10^3 mol of PCI3?

Answers

Answer:

980,536.2 grams

Explanation:

The mass of a compound is equal to its moles times its molar mass.

The molar mass of PCl3 is 137.33 g/mol

137.33 x 7.14 x 10^3 = 980,536.2

A/an _______ is the smallest unit of matter that has the characteristics of a chemical element. Question 9 options: A) proton B) atom C) molecule D) electron

Answers

Answer: atom

Explanation: molecule is a group or two or more atoms

protons and electron are subatomic particles

atom is the smallest unit of matter

What is the equilibrium constant equation for the chemical process below?
2A + B2 —> A₂B2

Answers

Let's see

[tex]\\ \rm\dashrightarrow k=\dfrac{Concentration\:of\: products}{Concentration\:of\: reactants}[/tex]

[tex]\\ \rm\dashrightarrow k=\dfrac{\left[A_2B_2\right]}{\left[A\right]^2\left[B\right]}[/tex]

When a chemical cold pack is activated, it becomes cool to the touch. What is happening in terms of energy?.

Answers

Answer:

An exothermic reaction is happening, it is absorbing the cold.

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Which Compound can be used to preserve biological specimens?

1/2/3?

Answers

Biological specimens are the preserved remains of the biological materials. Compound A. formaldehyde or formalin is used to preserve the specimens. Thus, option A is correct.

What are fluid-preserved specimens?

Fluid preserved specimens are the biological material of the organism that are kept at the store to study and analyze over a long time without getting any damage. Formaldehyde along with alcohol is the most common preservative.

Formaldehyde is an organic compound that is colorless and pungent in the smell that preserves the dead remains of the organisms intact. It is antiseptic and germicide in nature that makes them best for the purpose.

Therefore, option A. formaldehyde is used to preserve the specimens.

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Answer:

so i put a...

Explanation:

Edge doesnt give correct answers on unit tests, but i passed with an 88 :)

Correct me if im wrong!!

Complete the sentence using the word refracting, radlo, or space.
Telescopes that use lenses to bend light are called
telescopes.

Answers

Answer:

Refracting

Explanation:

Mark the word bend lightHence light travels through one medium to another it bends down which is called refraction.The bendness depends upon the refractive index of medium.

Based on your research, which source of energy do you think best meets the needs of society? Defend your answer in 50 to 100 words.

Answers

Currently, fossil fuels meet the 80% of needs of the society. But it is a non-renewable source, and it will extinct soon. The leading renewable source is wind power.

What is the non-renewable and renewable source?

Non-renewable energy are the energies that will require a thousand of years to make and ones extinct, will not be prepared.

Renewable energy sources can be prepared again and again, examples are wind, solar, hydropower.

Thus, the fossil fuel and wind power is the leading source of energy that meets the needs of society.

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1 Identify Draw an example of a force acting on an object.

Answers

Answer:

Answer below

Explanation:

Just draw a photo of someone pushing an object across a table. Your push is the force acting on the object you're pushing.

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What is the wavelength of a wave that has a frequency of 6.1 x 10^9 Hz? Remember that c = 2.998 x 10^8 m/s.

A.) 52m

B.) 5.2m

C.) 0.49m

D.) 0.049m

Answers

Answer:

speed = wavelength × frequency

wavelength = Speed/frequency

wavelength = 2.998 x 10^8 m/s ÷ 6.1 x 10^9 Hz

wavelength = 0.049m

How many grams of sodium hydroxide, NaOH, are needed to make 355.0 mL of a 4.75M solution? The molar mass of NaOH is 40.00 g/mol

Answers

Answer:

4198.97404999

Explanation:

In chemistry, the formula weight is a quantity computed by multiplying the atomic weight (in atomic mass units) of each element in a chemical formula by the number of atoms of that element present in the formula, then adding all of these products together.

Using the chemical formula of the compound and the periodic table of elements, we can add up the atomic weights and calculate molecular weight of the substance.

If the formula used in calculating molar mass is the molecular formula, the formula weight computed is the molecular weight. The percentage by weight of any atom or group of atoms in a compound can be computed by dividing the total weight of the atom (or group of atoms) in the formula by the formula weight and multiplying by 100.

Please Help I need an explanation on how to do this

Answers

Balanced equation(That should be NaClO_3)

[tex]\\ \rm\Rrightarrow Cl_2+2NaOH\longrightarrow NaCl+NaClO_3+H_2O[/tex]

Remember that it's a ionic equation not general equation

So

We have to balance it accordingly

Answer:

Balanced equation(That should be NaClO_3)

\begin{gathered}\\ \rm\Rrightarrow Cl_2+2NaOH\longrightarrow NaCl+NaClO_3+H_2O\end{gathered}⇛Cl2+2NaOH⟶NaCl+NaClO3+H2O

Remember that it's a ionic equation not general equation

So

We have to balance it accordingly

for now pliss help me ​

Answers

In the nucleus of the cell I think

Answer:

the nucleoid

Explanation:

H+ ion concentration of 2.5 x 10-5

Answers

Answer:

What is the hydrogen ion concentration of a solution labeled "Solution A", whose pH is 5.60? 

Tutorial

In this problem we are given pH and asked to solve for the hydrogen ion concentration. Using the equation, pH = − log [H+] , we can solve for [H+] as,

− pH = log [H+] ,

[H+] = 10−pH,

by exponentiating both sides with base 10 to "undo" the common logarithm. The hydrogen ion concentration of "Solution A" is,

[H+] = 10−5.6 ≈ 0.0000025 = 2.51 × 10−6 M.

We can always check our solution by computing −log (2.5 × 10−6) ≈ 5.6.

Continued deforestation will most likely lead to _______. a. a decrease in the number of endangered species b. an increase in the number of endangered species c. an increase in the number of oil and chemical spills d. a decrease in glacial melting please select the best answer from the choices provided a b c d

Answers

Deforestation often leads to an increase in the number of endangered species of plants and or animals.

What is deforestation?

Deforestation refers to the conversion of forests to non-forest uses. In other words, it is the removal of forest layers for non-forest reasons.

Since forests represent a hotspot for plant and animal biodiversity, their removal automatically means a decrease in biodiversity.

Endangered species are species of plants and animals that are under the threat of going extinct either due to natural or anthropological effects.

Thus, deforestation often leads to an increase in the number of endangered species.

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Answer:

b

Explanation:

Use the word bank below to complete the statement. Not all of the words will be used.
Word Bank:
sum. Enthalpy. Heat. Total.
Temperature. Moles. -ΔH. +ΔH.

Hess’s Law describes how the ____ energy of a reaction consists of the ___ of the energy changes of the individual step reactions.

Answers

Answer:

Hess’s Law describes how the __Heat__ energy of a reaction consists of the _Enthalpy__ of the energy changes of the individual step reactions

Explanation:

Hess law is a legendary law which is given by

[tex]\\ \rm\Rrightarrow ∆H_{net}=\sum \delta H_r[/tex]

what is the molarity of liters of an aqueous solution that contains 0.50 mole of potassium iodide, KI

Answers

Answer:

The molarity of 2.0 liters of an aqueous solution that contains 0.50 mol of potassium iodide is 0.25M.HOW TO CALCULATE MOLARITY:The molarity of a solution can be calculated by dividing the number of moles by its volume. That is;Molarity = no. of moles ÷ volumeAccording to this question, 2.0 liters of an aqueous solution that contains 0.50 mol of potassium iodide. The molarity is calculated as follows:Molarity = 0.50mol ÷ 2LMolarity = 0.25MTherefore, the molarity of 2.0 liters of an aqueous solution that contains 0.50 mol of potassium iodide is 0.25M.Learn more about molarity at: brainly.com/question/2817451

Explanation:

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Zinc metal is added to hydrochloric acid to generate hydrogen gas and is collected over a liquid whose vapor pressure is the same as that of pure water at 20.0°C (18 torr). The volume of the mixture is 1.7 L, and its total pressure is 0.788 atm. Determine the number of moles of hydrogen gas present in the sample.

Answers

Answer:

About 0.054 moles.

Explanation:

Apply the ideal gas law. Recall that:

[tex]\displaystyle PV = n RT[/tex]

Solve for n, the number of moles:


[tex]\displaystyle n = \frac{PV}{RT}[/tex]

Determine the pressure of the hydrogen gas. Recall that by Dalton's Law of Partial Pressures, the total pressure is equal to the sum of the partial pressures of each individual gas:


[tex]\displaystyle P_T = P_\ell + P_\text{H$_2$}[/tex]

Convert the vapor pressure of the liquid to atm (1.00 atm = 760. torr):


[tex]\displaystyle 18\text{ torr} \cdot \frac{1.00\text{ atm}}{760.\text{ torr}} = 0.024\text{ atm}[/tex]

Therefore, the partial pressure of the hydrogen gas is:


[tex]\displaystyle \begin{aligned} P_T & = P_\ell + P_\text{H$_2$} \\ \\ (0.788\text{ atm}) & = (0.024\text{ atm}) + P_\text{H$_2$} \\ \\ P_\text{H$_2$} & = 0.764\text{ atm}\end{aligned}[/tex]

Therefore, the number of moles of hydrogen gas present is (the temperature in kelvins is 273.15 + 20.0 = 293.2 K):


[tex]\displaystyle \begin{aligned} n & = \frac{PV}{RT} \\ \\ & = \frac{(0.764\text{ atm})(1.7\text{ L})}{\left(0.08206 \text{ }\dfrac{\text{L-atm}}{\text{mol-K}}\right)(293.2\text{ K})}\\ \\ & = 0.054\text{ mol H$_2$} \end{aligned}[/tex]

How do I learn a subject easier

Answers

Say out loud what you want to remember.

Take notes by hand, not on a computer.

Chunk your study sessions.

Test yourself. A lot.

Change the way you practice.

Exercise regularly.

Get more sleep.

Learn several subjects in succession.

So if u want to learn a subject easily then what u recommend u do is get someone to talk to you, revise (I’m bad at it tho) don’t over work urself. Take some notes of the subject ur wanting to learn . Don’t take ages learning that or you’ll fall behind on all the other subjects so yh


A gas occupies a volume of 140. mL at STP. What is the volume of the gas at 25°C and 3.00 atm

Answers

At STP

pressure is 1atm

So

Apply Boyles law

P1V1=P2V2140(3)=1V2420=V2V2=420mL

what type of element is always radioactive?

Answers

Uranium, Promethium, Polonium, also known as isotopes.

how do energy sources poly a role in the rock formation?

Answers

Sun (radiation), winds (eolic) and water (hydraulic) are all sources of energy that work together during rock formation.

What is rock formation?

The rock formation is a very slow process that occurs at a geological time, which may take millions of years.

During this period, rocks are shaped by different types of energy, especially radiation and erosion (wind and water bodies)

In conclusion, the sun (radiation), winds (eolic) and water (hydraulic) work together during rock formation.

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20 Infer Check the box to show which would tell you for sure if you had a sample of real gold.
Color of your sample. Yes No
What happens when you strike your sample with a hammer.
The location where your sample was found.

Answers

Answer:

C but read the limitation

Explanation:

Gold sample

Color wouldn't tell you much. In fact it may fool you. Fool's Gold is the same color as gold.

Gold is very malleable. That's what hitting gold with a hammer will do.  It tends to shape the gold without destroying it into lots of pieces. A lot of yellow things have that property.

If only it was that simply. Yes if you are sure there is gold in that location. You have to pick this answer, because the other 2 don't work. So this is possible, but not the best way. The best way is to subject the sample to chemical treatment. If you are left with a yellow sample, then you could make the case for it being gold.

How is an unknown oxidation state of an element within a compound
determined?
O A. It will be the same in the products as in the reactants.
B. It will be the same as the charge on the compound.
C. It is always the same as the most likely oxidation state.
ОС
OD. It is determined from known oxidation states of other elem

Answers

Answer:

it is determined from known oxidation states of other elements

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The base Ba(OH)2 neutralizes the acid H2SO4 according to the equation below. What salt is produced?

H2SO4 + Ba(OH)2 -->

A. BaSO4

B. BaH2

C. BaH2S

D. BaO4

Answers

Answer:

According to the equation below salt is produced by BaH2s

Answer:

I think b is the correct answer

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