Question Video: Determining the Number of Protons- Neutrons- and Electrons in an Ion from the Nuclide Notation Chemistry

An ion of copper has the nuclide notation 65 29 Cu²⁺. a) How many protons are there in this ion of copper? b) How many neutrons are there in this ion of copper? c) How many electrons are there in this ion of copper?

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Video Transcript

An ion of copper has the nuclide notation shown. Part (a) how many protons are there in this ion of copper?

In this question, we are shown the nuclide notation of a copper ion. Nuclide notation is a way to represent the number of subatomic particles in an atom, ion, or isotope of an element. In this problem, we will specifically focus on an ion of the element copper. Recall that there are three subatomic particles. Protons are positively charged subatomic particles found in the nucleus. Neutrons are neutral, which means that they do not have any charge. They are also found in the nucleus. While protons and neutrons are about the same size, electrons are quite a bit smaller. Electrons are negatively charged subatomic particles found in the electron cloud outside of the nucleus.

Nuclide notation can be used to represent the number of these subatomic particles in a specific ion in the following way. E represents the chemical symbol of the element. Let’s write out the nuclide notation for the copper ion and interpret each part. We already know that the chemical symbol Cu represents the element copper. The letter Z in nuclide notation which appears in the bottom-left corner is the atomic number. This means that the atomic number of the copper ion is 29. The atomic number is equal to the number of protons in the nucleus. Therefore, there are 29 protons in the nucleus of this ion of copper.

Part (b) how many neutrons are there in this ion of copper?

Let’s continue to interpret the nuclide notation of the copper ion. The letter A in nuclide notation, which appears in the top-left corner, is the mass number. This means that in the copper ion, the mass number is 65. The mass number is equal to the number of protons in the nucleus plus the number of neutrons in the nucleus. Let’s substitute in the values for the mass number and number of protons for the copper ion into this equation. We get 65 is equal to 29 plus the number of neutrons. When we solve for the number of neutrons, we get an answer of 36. There are 36 neutrons in this ion of copper.

Part (c) how many electrons are there in this ion of copper?

In the atom of an element, the number of protons in the nucleus is equal to the number of electrons in the electron cloud. Inside the nucleus of this generic drawing of an atom, we see that there are two positively charged protons. Outside of the nucleus in the electron cloud are two negatively charged electrons. When we add up the charge of positive two from the protons and negative two from the electrons, we get an answer of zero, which is why we say that atoms have no net charge or are neutral. On the other hand, ions of elements do have a net charge. In nuclide notation, the charge on the ion is shown in the upper-right corner. We can see that the charge of the copper ion is two plus. Let’s use this simplified drawing of a copper ion to analyze the number of subatomic particles inside.

In parts (a) and (b) of the question, we already determined that the nucleus of the copper ion contains 29 protons and 36 neutrons. In an ion, the number of protons and electrons are not equal. We’ll need to make use of the following equation to determine the number of electrons in the ion. Let’s substitute in the charge and the number of protons into this equation. After solving for the number of electrons, we get an answer of 27. The electron cloud of the copper ion contains 27 electrons. There are 27 electrons in this ion of copper.

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