Using data from this chapter, calculate the change in energy...

Using data from this chapter, calculate the change in energy expected for each of the following processes. a. $\mathrm{Na}(g)+\mathrm{Cl}(g) \rightarrow \mathrm{Na}^{+}(g)+\mathrm{Cl}^{-}(g)$ b. $\mathrm{Mg}(g)+\mathrm{F}(g) \rightarrow \mathrm{Mg}^{+}(g)+\mathrm{F}^{-}(g)$ c. $\mathrm{Mg}^{+}(g)+\mathrm{F}(g) \rightarrow \mathrm{Mg}^{2+}(g)+\mathrm{F}^{-}(g)$ d. $\mathrm{Mg}(g)+2 \mathrm{~F}(g) \rightarrow \mathrm{Mg}^{2+}(g)+2 \mathrm{~F}^{-}(g)$

Using data from this chapter, calculate the change in energy expected for each of the following processes.
a. $\mathrm{Na}(g)+\mathrm{Cl}(g) \rightarrow \mathrm{Na}^{+}(g)+\mathrm{Cl}^{-}(g)$
b. $\mathrm{Mg}(g)+\mathrm{F}(g) \rightarrow \mathrm{Mg}^{+}(g)+\mathrm{F}^{-}(g)$
c. $\mathrm{Mg}^{+}(g)+\mathrm{F}(g) \rightarrow \mathrm{Mg}^{2+}(g)+\mathrm{F}^{-}(g)$
d. $\mathrm{Mg}(g)+2 \mathrm{~F}(g) \rightarrow \mathrm{Mg}^{2+}(g)+2 \mathrm{~F}^{-}(g)$

Key Concepts

Successive Ionization Energies

For atoms that can lose more than one electron, successive ionization energies refer to the energy required to remove an electron from an already positively charged ion. These values are typically higher than the first ionization energy due to the increased effective nuclear charge experienced by the remaining electrons. Accounting for successive ionization energies is important in correctly evaluating processes where multiple electrons are removed.

Ionization Energy

Ionization energy is the energy required to remove an electron from a gaseous atom or ion. It is a fundamental property that reflects how strongly an electron is held by an atom. When calculating energy changes for processes that involve forming cations, one must account for the ionization energies of the atoms involved, including successive ionization energies if more than one electron is removed.

Electron Affinity

Electron affinity is the energy change that occurs when an electron is added to a neutral atom in the gaseous phase, forming a negative ion. This concept is crucial when determining the energy change for processes that involve the formation of anions, as electron affinity values indicate whether energy is released or absorbed during the electron attachment.

Energy Calculation in Ionic Processes

When analyzing reactions that involve the formation of ions from neutral atoms, the overall energy change is determined by summing the energies of the individual steps. This includes subtracting the energy released by electron attachment (electron affinity) from the energy required for electron removal (ionization energy). Understanding how to combine these values is key to accurately predicting the net change in energy for a given process.

Transcript

00:01 To answer these questions, we use the properties of ionization energy and electron affinity.

00:06 These give energy values for the changing of atoms into ions.

00:11 And in the textbook are table 7 .5 and 7 .7.

00:16 But you can also find the information in lots of other places.

00:19 So again, you're looking for the idea of ionization energy and electron affinity.

00:24 So when we look at a, we can see two processes happening.

00:28 The first is that a sodium atom loses an electron to become an a -plus.

00:38 This process is ionization, and so to find the energy involved in that, we look at the ionization energy.

00:50 Your table may have several ionization energies listed.

00:54 This is the first ionization energy for sodium.

00:59 The second process that we see is chlorine.

01:04 Gaining an electron to make cl minus the ion.

01:09 When an atom gains an electron, the energy involved is called the electron affinity.

01:20 So looking on tables, we can find the energy associated with each of these processes, and then the overall energy is just the sum of those two things.

01:28 So the ionization energy of sodium forming na plus, we should find it to be 495 kilojoules.

01:37 And the ionization of chlorine to form cl minus is minus 348 kilojoules.

01:48 So we just add those two numbers together to get an overall energy of 147 kilojoules.

02:04 Question b is very similar.

02:07 In this case we have magnesium and fluorine.

02:10 So the magnesium loses an electron to form mg plus.

02:17 And fluorine gains an electron to form f minus.

02:24 So again, this is the first ionization energy, and this is the electron affinity.

02:46 And so looking on the tables, we find the ionization energy for this process to be 735 kilojoules, and the electron affinity for this process to be minus 327.

03:07 So adding those two numbers together, we get 407 kilojoules...

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