What is the mass number of an element?

Answers

Answer 1
sum of protons and neutrons
Answer 2
An element's mass number (A) is the sum of the number of protons and the number of neutrons. The small contribution of mass from electrons is disregarded in calculating the mass number.


Together, the number of protons and the number of neutrons determine an element's mass number: mass number = protons + neutrons. If you want to calculate how many neutrons an atom has, you can simply subtract the number of protons, or atomic number, from the mass number.

The atomic mass of an element is the average mass of the atoms of an element measured in atomic mass unit (amu, also known as daltons, D). The atomic mass is a weighted average of all of the isotopes of that element, in which the mass of each isotope is multiplied by the abundance of that particular isotope.

Related Questions

what is the name of the shape that is a quadrilateral where all 4 sides are the same length
HELP QUICK

Answers

Answer:

Square

Explanation:

A square is a quadrilateral with r sides the same length

When writing the formulas for a compound that contains a polyatomic ion, ... ?​

Answers

Answer:

The cation is written first in the name; the anion is written second in the name. Rule 2. When the formula unit contains two or more of the same polyatomic ion, that ion is written in parentheses with the subscript written outside the parentheses.

When writing the formula of a compound that contains polyatomic ion, the metal is written first followed by the central atom in the ion and then other atoms that surround the central atom.

A poly atomic ion refers to an ion that comprises of more than one atom. Such ions are common in chemistry. Examples of polyatomic ions include; PO4^3-, BH4^- etc.

When writing the formula of a compound that contains a polyatomic ion, the metal is written first then the central atom in the ion follows before other atoms that surround the central atom in the ion.

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Meera added blue copper sulphate crystals to some water in a beaker.
The copper sulphate dissolved in the water.
1 give one way meera could see that the copper sulphate had dissolved in the

Answers

Answer:

The solid crystals disappeared

Explanation:

When a soluble solid solute is added to water, the solid solute disappears after a little while. The disappearance of this solute indicates that the solute has been dissolved in water.

In this case, blue copper sulphate crystals are added to water, the blue crystals disappear leaving only a blue solution. The disappearance of these blue copper sulphate crystals indicates that the substance has dissolved in water.

2). A student collects 425 L of oxygen at a temperature of 24.0°C and a pressure
of 0.899 atm. How many moles of oxygen did the student collect?

Answers

Answer:

15.5 moles

Explanation:

Applying,

PV = nRT.................. Equation 1

Where P = pressure, V = Volume, n = number of mole, R = molar gas constant, T = Temperature.

Make n the subject of the equation

n = PV/RT............... Equation 2

From the question,

Given: P = 0.899 atm, V = 425 L, T = 24 °C = (273+24) K = 297 K.

Constant: R = 0.083 L.atm/K.mol

Substitute these values into equation 2

n = (0.899×425)/(297×0.083)

n = 15.5 moles

A solution has a [OH−] of 1 × 10−12 M. What is the [H3O+] of the solution?
1 × 10−14 M
1 × 10−2 M
2 M
14 M

Answers

1x10-2

U welcome. Hope that helps

Answer: The awnser is B

Explanation:

Help help help I will give brainliest

Answers

Answer:

its b alkyne

Explanation:

brinliest po plsss

Answer:

Alkyne so its b

balance FeCl3 + MgO ---> Fe2O3 + MgCl2

Answers

Answer: The balanced equation is [tex]2FeCl_{3} + 3MgO \rightarrow Fe_{2}O_{3} + 3MgCl_{2}[/tex]

Explanation:

The given reaction equation is as follows.

[tex]FeCl_{3} + MgO \rightarrow Fe_{2}O_{3} + MgCl_{2}[/tex]

Here, number of atoms present on reactant side are as follows.

Fe = 1Cl = 3Mg = 1O = 1

Number of atoms on product side are as follows.

Fe = 2Cl = 2Mg = 1O = 3

To balance this equation, multiply [tex]FeCl_{3}[/tex] by 2 and MgO by 3 on reactant side. Also, multiply [tex]MgCl_{2}[/tex] by 3 on product side. Therefore, the equation can be rewritten as follows.

[tex]2FeCl_{3} + 3MgO \rightarrow Fe_{2}O_{3} + 3MgCl_{2}[/tex]

Hence, number of atoms on reactant side are as follows.

Fe = 2Cl = 6Mg = 3O = 3

Number of atoms on product side are as follows.

Fe = 2Cl = 6Mg = 3O = 3

Since, this equation contains same number of atoms on both reactant and product side. Therefore, this equation is now balanced equation.

Thus, we can conclude that the balanced equation is [tex]2FeCl_{3} + 3MgO \rightarrow Fe_{2}O_{3} + 3MgCl_{2}[/tex].

WILL MARK BRAINLIEST
What is the oxidation state of Carbon in CaC2O4?

Answers

Answer:

The oxidation state of carbon in CaC204 is 3

Answer:The oxidation number of the carbons + the oxidation numbers of the oxygens must equal -2. Carbons + (-8) = -2 so the oxidation number of the carbons must be +6. Since there are 2 carbon atoms each must contribute +3 each. What is the oxidation number of S in Na2S2O3?

Explanation:

The oxidation state of Oxygen is -2 and that of Calcium is +2. There are four oxygen atoms which amounts to -8 charge. This leaves a charge of +6 on Carbon

A jar is filled to the top with water, and a piece of cardboard is slid over the opening so that there is only water in the . If the jar is now turned over, will the cardboard fall off? What will happen if there is any air in the jar?

Answers

Answer:

it will all fall unless these is air

Explanation:

Answer:

If you do it carefully enough, a small amount of water will pour out of the glass — that's supposed to happen. But try not to let any air bubbles get into the glass. Finally, slowly remove the hand holding the cardboard in place.

Which processes involve nuclear changes?
A. fission and fusion
B. erosion and weathering
C. combustion and oxidation
D. evaporation and condensation

Answers

Answer:

Nuclear processes, including fusion, fission, and radioactive decays of unstable nuclei, involve changes in nuclear binding energies.

Explanation:

mark me brainliest please

Help calculate the density and please type it like this and explain how you got the answer thanks

Mass:
Volume;
Density:

Answers

Answer: 2.5

Explanation:

density= 2.5

mass= 62.5 or 62.50

volume= 25 ( 75-50= 25)

so divide 62.5( or 62.50) by 25 which will led you to 2.5

Consider the Hertzsprung Russell diagram seen here. We can use this diagram to classify stars and determine their characteristics.
The color of a star is determined by its temperature: the hottest stars are blue and the coolest are red. The Sun has a surface
temperature of 5,500°C and it appears yellow. The diagram also indicates that temperature coincides with luminosity: the hotter the
star, the higher the luminosity. You can also tell the size of each star from the graph as the larger the radius, the higher the
temperature and luminosity. Regardless of a star's position in the diagram, the energy that results in high temperatures and the stars
luminosity is generated by what process?
W
A)
nuclear fusion
B)
nuclear fission
gravitational forces of swirling gases
D)
friction generated by gravitational force

Answers

Answer:

Explanation:

A- nuclear fusion

2. Identify the limiting reactant when 4.68 g of iron reacts with 2.88 g of sulfur to produce Fes.
Fe +
_Sg → FeS
B
C с
A
+


Help please I’ll mark brainliest

Answers

Answer:

Iron is limiting reactant

Explanation:

Based on the reaction:

Fe + S → FeS

1 mole of iron reacts per mole of Sulfur

To solve this question we must convert the mass of each reactant to moles using molar masses of each reactant. As the reaction is 1:1, the reactant with the lower amount of moles is limiting reactant.

Moles Fe -Molar mass: 55.845g/mol-

4.68g * (1mol / 55.845g) = 0.0838 moles

Moles S -Molar mass: 32.065g/mol-

2.88g * (1mol / 32.065g) = 0.0898 moles

As the amount of moles of Fe < Moles S,

Iron is limiting reactant

When 4.68 g of iron reacts with 2.88 g of sulfur to produce FeS, iron is the limiting reagent.

What is limiting reagent?

If in a chemical reaction two reactants are present and one of them is present in less quantity as compared to other, is known as limiting reagent.

Given chemical reaction is:
Fe + S → FeS

From the stoichiometry of the reaction it is clear that equal moles of both reactant is required for the formation of product, so their mole ratio is 1:1.

Now we calculate the moles by using the formula:

n = W/M, where

W = given mass

M = molar mass

Moles of 4.68g of iron = 4.68g / 55.845g/mole = 0.0838 moles

Moles of 2.88 of sulfur = 2.88g / 32.065g/mole = 0.0898 moles

Moles of iron is less as compare to the sulfur, so it is the limiting reagent.

Hence, iron is the limiting reagent.

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Which is NOT part of the male reproduction system of a flower? stamen pollen anther pistil​

Answers

Answer:

Pistil

Explanation:

I believe it is the pistil, because the pistil is part of the female reproductive system of a flower. A stamen is for the male reproductive system.

I also think it’s pistil

What is the molarity of a solution prepared by dissolving 10.0 grams of NaOH in enough water to make a solution with a total volume of 2.40 liters?

O0.104 M NaOH
O0.201 M NaOH
O0.361 M NaOH
O0.412 M NaOH

Answers

Solution :

Molecular mass of NaOH is 23 g/mol .

So, number of moles of NaOH is given by :

[tex]n = \dfrac{10}{40}\ mole[/tex]

Now, we know molarity is given by :

[tex]Molarity = \dfrac{Number \ of \ moles\ of \ salute}{Volume ( in \ Liter ) }[/tex]

[tex]M = \dfrac{10}{40\times 2.4} \ M\\\\M = 0.104 \ M[/tex]

Hence, this is the required solution.

Answer: The answer is A O0.104 M NaOH

Explanation:

Determine the mass in grams of Avogadro's number of C12H22O11

Answers

Answer:

2.059524x10^26 if im not wrong

Explanation:

avogadro's number is 6.022x10^23

The author wanted to revise this story to allow readers to understand more fully how Coach Wilkins felt about the banquet and his career. What change would be MOST effective? Include the point of view of the coach by adding his thoughts and dialogue. A) Remove all the details about Josh, the cafeteria workers, and Principal Edwards B) Include more information on the activities with which Coach Wilkins was involved. Change the details to have Coach Wilkins deciding to teach social studies and coach footbalL D) y Comprehension​

Answers

Answer:D

Explanation:i did the usa test prep

Answer:answer is D

Explanation:

Which element, when combined with Fluorine, would form an COVALENT compound?

A.Lithium
B.Iron
C.Phosphorus
D.Sodium

Answers

Answer:

Explanation:

A covalent compound is a compound formed by covalent bonds. A covalent bond is formed between two atoms where electrons are shared between the two atoms. This forms a molecule.

What determines whether two elements will form a covalent compound or not is the number of valence electrons present in each of the elements.

Fluorine will form a covalent compound with phosphorous because fluorine has 5 electrons in its outermost shell. It needs 3 more to become stable.

Phosphorous also has 5 valence electrons. It needs 3 more to become stable.

What happens is that 3 atoms of FLuorine combine with one atom of Phosphorus, sharing the valence electrons between themselves. This leads to the formation of the PF3 molecule.

Both the Phosphorous and the Fluorine are now stable.

Answer: Phosphorus

Explanation: since both are non-metals they would both create a covalent bond.

Please help me with number 43

Answers

Answer:

The reason why atomic mass is usually not a whole number is because it is a weighted average of the mass numbers of isotopes

Explanation:

Which model illustrates a compound A, b, c, d,

Answers

Answer: C

Explanation: I have the same question, it’s for summit, my teacher helped me with this question :)

Oxygen has 6 valence electrons. how many hydrogen atoms (who have 1 valence electrons) can bond with it? remember the octet rule.

Answers

Answer:

two hydrogen can bonded with oxygen to form H2O

HELP ME PLEASEEEEE its chem
1. The thermal waters of a spring have a hydronium ion (H3O+) concentration of 2.00 x 10-6 M. Calculate the pH of the water.

2. Acetic acid (CH3COOH) is one of the simplest carboxylic acids. It is an important chemical reagent and industrial chemical. Vinegar is dilute acetic acid, often produced by fermentation. The following is a reversible reaction:
CH3COOH ↔ H+ + CH3COO–
• Write the set up you would use to calculate the Ka of this reaction.
• Calculate the hydrogen ion concentration [H+] of a 0.1 M solution of acetic acid given that the dissociation constant of acetic acid is Ka = 1.8 x10–5. Work must be shown to earn credit.

3. Describe the reaction of a strong acid and a weak base. In general, what will the final pH be when the reaction between equal moles of a weak acid and a strong base is complete? Explain your answer.

Answers

Answer:The thermal waters of a spring have a hydronium ion (H3O+) concentration of 2.00 x . 2. Acetic acid (CH3COOH) is one of the simplest carboxylic acids. It is an important chemical reagent and industrial chemical.Have a hydronium ion (H3O+) concentration of 2.00 x 10-6 M. Calculate the pH of the water.

Explanation: The thermal waters of a spring have a hydronium ion (H3O+) concentration of 2.  spring have a hydronium ion (H3O+) concentration of 2.00 x 10-6 M. Calculate the pH of the water. 2. Acetic acid (CH3COOH) is one of the simplest carboxylic acids. It is an important chemical reagent and industrial chemical.

Why is the temperature of products likely to be lower than the temperature of reactants in an endothermic reaction?​

Answers

Reactants + Energy → Products. Note: ΔH represents the change in energy. In endothermic reactions, the temperature of the products is typically lower than the temperature of the reactants. ... The energy needed for the reaction to take place comes from the water, which gets colder as the reaction proceeds.

Which formula represents an isomer of this compound?

Answers

Answer:

Explanation:

I can’t explain but this is the answer LOL

Which statement is true about the rotational period of the moon?


greater than the revolution period around Earth


always changing


less than the revolution period around Earth


equal to the revolution period around Earth

Answers

less than the revolution perilous around earth

The statement is true  about the rotational period of the moon " the rotational period of the moon is equal to the revolution period around Earth."

What is rotational period?

A celestial object's rotation period may relate towards its sidereal rotation period, which is the time it takes for the object to complete one revolution around in its axis of rotation in sidereal seems like to the background stars.

What is revolution period?

The orbital period is also known as the revolution period. it takes for one astronomical object to complete one cycle around another. It refers to planets and asteroids orbiting the Sun, moons orbiting planets, planetary systems orbiting other stars, or double stars in astronomy.

What is moon?

In the night sky, the moon is just the brightest object. The moon doesn't at all produce its own light. It has no radiance. That is visible because the sun's light bounces off of it.

The rotational period of the moon is equal to the revolution period around Earth because the moon's rate of spin becomes tidally locked to its rate of revolution, it maintains the same face oriented towards the Earth In other words, every time the moon rounds the Earth, it rotates exactly once.

Therefore, the rotational period of the moon is equal to the revolution period around Earth will be correct answer.

To know more about rotational period click here.

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Ammonia gas (NH3) combines with oxygen gas (O2) to form diatomic nitrogen gas and water vapor. If 4.0 grams of ammonia react, how many liters of nitrogen gas are produced? The gas is collected at 32.00°C and a pressure of 2.6 atmospheres.

Answers

Answer:

1.13 L

Explanation:

First, we have to write the chemical equation for the reaction between ammonia gas (NH₃) and oxygen gas (O₂) to give nitrogen gas (N₂) and water (H₂O), as follows:

NH₃(g) + O₂(g) → N₂(g) + H₂O(g)

Then, we have to balance the equation (we write first the coefficient 2 for NH₃ to balance N atoms, then a coefficient of 3 for H₂O to balance H atoms, and finally 1/3 to balance the O atoms):

2 NH₃(g) + 3/2 O₂(g) → N₂(g) + 3 H₂O(g)

In the balanced equation, we can see that 1 mol of N₂ is produced from 2 moles of NH₃. We convert the moles of NH₃ to grams by using its molecular weight (MW):

MW(NH₃) = 14 g/mol N x 1 + (1 g/mol H x 3) = 17 g/mol

grams of NH₃ = 17 g/mol x 2 = 34 g

Thus, we have the stoichiometric ratio:

1 mol of N₂/2 mol NH₃ = 1 mol of N₂/34 g NH₃

To calculate how many moles of N₂ are produced from 4.0 of NH₃, we multiply the mass by the conversion factor:

4.0 g NH₃ x 1 mol of N₂/34 g NH₃ = 0.1176 moles N₂

Finally, we calculate the liters of N₂ gas by using the ideal gas equation:

PV = nRT ⇒ V = nRT/P

We introduce the data in the equation:

T = 32.00°C + 273 = 305 K

P = 2.6 atm

R = 0.082 L.atm/K.mol (is the gas constant)

n= 0.1176 moles

⇒ V = nRT/P = (0.1176 mol x 0.082 L.atm/K.mol x 305 K)/(2.6 atm)

                     = 1.13 L

A chemist observed bubbling and fizzing after adding an acid solution to a
white powdery substance in a beaker. Which of the following can be
inferred?

Answers

Answer:

a chemical reaction occured

Explanation:

bubbling and fizzing after adding a substance, most offten means a chemical reaction is happening

(part 1 of 3) Copper reacts with silver nitrate through a single replacement. If 1.29 g of silver are produced from the reaction, how much copper(II) nitrate is also produced? Answer in units of mol. (part 2 of 3) How much Cu is required in this reaction? Answer in units of mol. (part 3 of 3) 1.0 points How much AgNO3 is required in this reaction? Answer in units of mol.

Answers

Answer:

See explanation.

Explanation:

Hello there!

In this case, according to the described chemical reaction, we first write the corresponding equation to obtain:

[tex]Cu+2AgNO_3\rightarrow 2Ag+Cu(NO_3)_2[/tex]

Thus, we proceed as follows:

Part 1 of 3: here, since the molar mass of silver and copper (II) nitrate are 107.87 and 187.55 g/mol respectively, and the mole ratio of the former to the latter is 2:1, we can set up the following stoichiometric expression:

[tex]m_{Cu(NO_3)_2}=1.29gAg*\frac{1molAg}{107.87gAg}*\frac{1molCu(NO_3)_2}{2molAg}*\frac{187.55gCu(NO_3)_2}{1molCu(NO_3)_2} \\\\m_{Cu(NO_3)_2}=1.12gCu(NO_3)_2[/tex]

Part 2 of 3: here, the molar mass of copper is 63.55 g/mol and the mole ratio of silver to copper is 2:1, the mass of the former that was used to start the reaction was:

[tex]m_{Cu}=1.29gAg*\frac{1molAg}{107.87gAg}*\frac{1molCu}{2molAg}*\frac{63.55gCu)_2}{1molCu} \\\\m_{Cu}=0.380gCu[/tex]

Part 3 of 3: here, the molar mass of silver nitrate is 169.87 g/mol and their mole ratio 2:2, thus, the mass of initial silver nitrate is:

[tex]m_{AgNO_3}=1.29gAg*\frac{1molAg}{107.87gAg}*\frac{2molAgNO_3}{2molAg}*\frac{169.87gAgNO_3}{1molAgNO_3} \\\\m_{AgNO_3}=2.03gAgNO_3[/tex]

Best regards!

How many moles of hypomanganous acid. H3 MnO4, are contained in 22.912 g?

Answers

Answer:

0.188mol

Explanation:

Using the formula;

mole = mass/molar mass

Molar mass of hypomanganous acid. (H3MnO4) = 1(3) + 55 + 16(4)

= 3 + 55 + 64

= 122g/mol

According to this question, there are 22.912g of H3MnO4

mole = 22.912g ÷ 122g/mol

mole = 0.188mol

6. What happens when :
a)
manganese dioxide is heated with conc.
hydrochloric
acid.​

Answers

Answer:

Chlorine gas is produced

Explanation:

One of the methods of laboratory preparation of chlorine gas is to heat manganese dioxide with concentrated hydrochloric acid. The acid is oxidized by the manganese dioxide to liberate chlorine gas as follows;

MnO2(s) + 4HCl(aq) -------> MnCl2(aq) + 2H2O(l) + Cl2(g)

Hence, When manganese dioxide is heated with concentrated hydrochloric

acid, chlorine gas is liberated.

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