Finding the number of electrons in a given substance

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In summary, the problem involves finding the number of electrons and free electrons in a copper wire based on its length, diameter, and mass. Using the atomic number and mass of copper, the number of moles of copper can be determined and then multiplied by Avogadro's Number to find the number of atoms. Finally, multiplying by the number of electrons per atom and free electrons per atom gives the answers for (a) and (b) respectively.
  • #1
ENCgirl
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Homework Statement



I was given this problem in class and I am unable to figure it out:

A copper wire 90.0 cm long and 1.00 mm in diameter has a mass of 6.35 grams.

(a) find the number of electrons in the wire ( Copper has an atomic number of 29; that is there are 29 protons in the copper atom. Copper has an atomic mass of 63.5)

(b) There is one free electron per atom in copper. Find the number of free electrons in the wire.

Homework Equations



Me= 9.11e-31

The Attempt at a Solution



.00635 kg = mass of the wire

(.00635kg) ( 9.11e-31 kg)= 5.8e-33 kg

I really do not know what to do...
Thank you for your help...
K.
 
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  • #2
ENCgirl said:

Homework Statement



I was given this problem in class and I am unable to figure it out:

A copper wire 90.0 cm long and 1.00 mm in diameter has a mass of 6.35 grams.

(a) find the number of electrons in the wire ( Copper has an atomic number of 29; that is there are 29 protons in the copper atom. Copper has an atomic mass of 63.5)

(b) There is one free electron per atom in copper. Find the number of free electrons in the wire.

Homework Equations



Me= 9.11e-31

The Attempt at a Solution



.00635 kg = mass of the wire

(.00635kg) ( 9.11e-31 kg)= 5.8e-33 kg

I really do not know what to do...
Thank you for your help...
K.

Atomic mass is 63.5...so your molar mass is 63.5 g/mol. Do you see how that helps you determine how many moles of copper you have (given your mass)? Then, what do you know about the number of moles and Avogadro's Number?

After all that, you'll know how many atoms of copper you have. Then you can just multiply by the number of electrons per atom for (a) and the number of free electrons per atom (b).
 
  • #3
Thank you sooo much! That helped a lot!
 

Related to Finding the number of electrons in a given substance

1. How do you find the number of electrons in a given substance?

To find the number of electrons in a substance, you need to know the atomic number of the element or compound. The atomic number represents the number of protons in the nucleus of an atom, which is equal to the number of electrons in a neutral atom. Therefore, the atomic number can be used to determine the number of electrons in a given substance.

2. Can the number of electrons in a substance change?

The number of electrons in a substance can change if the substance undergoes a chemical reaction or a nuclear reaction. During a chemical reaction, atoms can gain or lose electrons, resulting in a change in the number of electrons in the substance. In a nuclear reaction, the nucleus of an atom can also change, which can also affect the number of electrons in the substance.

3. What is the relationship between the number of electrons and the properties of a substance?

The number of electrons in a substance is directly related to its chemical and physical properties. The arrangement and behavior of electrons determine the chemical reactivity, electrical conductivity, and other properties of a substance. Therefore, the number of electrons plays a crucial role in the characteristics of a substance.

4. How do you determine the number of electrons in an ion?

An ion is an atom or molecule that has gained or lost one or more electrons, resulting in a net positive or negative charge. The number of electrons in an ion can be determined by looking at its charge. If the ion has a positive charge, it has lost electrons equal to the magnitude of its charge. If the ion has a negative charge, it has gained electrons equal to the magnitude of its charge.

5. Is it possible for a substance to have a fractional number of electrons?

No, it is not possible for a substance to have a fractional number of electrons. Electrons are indivisible particles, and the number of electrons in a substance must be a whole number. However, in certain situations, such as in some chemical compounds, the electrons may be shared between atoms, resulting in a partial electron charge, but the total number of electrons remains a whole number.

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