What Charge Does Chlorine Have

3.3: Ions

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Learning Objectives

• Ascertain the 2 types of ions.
• Employ Lewis diagrams to illustrate ion germination.

Most atoms practice not have eight electrons in their valence electron vanquish. Some atoms accept only a few electrons in their outer beat, while some atoms lack only 1 or two electrons to have an octet. In cases where an cantlet has three or fewer valence electrons, the atom may lose those valence electrons quite hands until what remains is a lower shell that contains an octet. Atoms that lose electrons learn a positive charge every bit a consequence because they are left with fewer negatively charged electrons to balance the positive charges of the protons in the nucleus. Positively charged ions are called cations. Nigh metals become cations when they brand ionic compounds.

Some atoms take near eight electrons in their valence beat out and can gain additional valence electrons until they take an octet. When these atoms gain electrons, they acquire a negative charge because they now possess more electrons than protons. Negatively charged ions are called anions. Virtually nonmetals get anions when they make ionic compounds.

The names for positive and negative ions are pronounced CAT-middle-ons (cations) and ANN-eye-ons (anions), respectively.

Electron Transfer

We can use electron configurations to illustrate the electron transfer process betwixt sodium atoms and chlorine atoms.

Na: 1due south ²2s ²2p ^half-dozen3s ¹

Every bit demonstrated here, a sodium atom (Na) has one valence electron in the third principal energy level. It is likely to achieve an octet in its outermost shell by losing its i valence electron. The cation produced in this way, Na⁺, is chosen the sodium ion to distinguish it from the element. The sodium ion, Na⁺, has the electron configuration with an octet of electrons from the 2d principal free energy level. Information technology is now the same as that of the noble gas neon. The term isoelectronic refers to an atom and an ion of a different atom (or two different ions) that have the same electron configuration. The sodium ion is isoelectronic with the neon atom. The equation below illustrates this process.

\[\begin{array}{lcl} \ce{Na} & \rightarrow & \ce{Na^+} + \ce{due east^-} \\ 1s^two \: 2s^2 \: 2p^half dozen \: 3s^i & & 1s^ii \: 2s^2 \: 2p^6 \: \text{(octet)} \finish{array} \nonumber \]

Figure \(\PageIndex{1}\) is a graphical depiction of this process.

Figure \(\PageIndex{ane}\): The Germination of a Sodium Ion. On the left, a sodium atom has xi electrons. On the right, the sodium ion only has 10 electrons and a 1+ charge.

Now, allow'south consider chlorine atom, Cl : 1s ²iis ²2p ^six3s ⁱⁱ3p^five

Only i more than electron is needed to achieve an octet in chlorine's valence trounce. When a chlorine atom gains an electron, its outermost main energy level achieves an octet. In this case, the ion has the aforementioned outermost crush every bit the original atom, merely now that shell has eight electrons in it. One time again, the octet rule has been satisfied. The resulting anion, Cl⁻, is called the chloride ion; annotation the slight change in the suffix (-ide instead of -ine) to create the name of this anion. This process is illustrated below. (In tabular array salt, this electron comes from the sodium cantlet.)

\[\brainstorm{assortment}{lcl} \ce{Cl} + \ce{east^-} & \rightarrow & \ce{Cl^-} \\ 1s^2 \: 2s^2 \:2p^6 \: 3s^two \: 3p^5 & & 1s^ii \: 2s^2 \: 2p^half dozen \: 3s^2 \: 3p^6 \text{(octet)} \end{array} \nonumber \]

Effigy \(\PageIndex{2}\) is a graphical depiction of this process.

Effigy \(\PageIndex{2}\): The Formation of a Chlorine Ion. On the left, the chlorine cantlet has 17 electrons. On the right, the chloride ion has 18 electrons and has a 1− charge.

With two oppositely charged ions, at that place is an electrostatic attraction betwixt them because opposite charges attract. The resulting combination is the compound sodium chloride. Observe that there are no leftover electrons. The number of electrons lost by the sodium atom (one) equals the number of electrons gained by the chlorine atom (one), so the compound is electrically neutral. In macroscopic samples of sodium chloride, at that place are billions and billions of sodium and chloride ions, although there is ever the aforementioned number of cations and anions.

Example \(\PageIndex{1}\)

Write the electron configuration of aluminum atom (Z=13). How many electrons must Al lose/gain to accomplish octet? Write the formula of the resulting ion and its electron configuration.

Solution

The electron configuration of Al cantlet is isouthward ²2s ^two2p ⁶3s ^two3p¹ . The second shell has octet ( twos ²2p ⁶) while the valence shell has 3 electrons (3s ⁱⁱ3p^ane ). Mg tin achieve octet by losing the 3 valence electrons. The resulting cation is Al^{3 +} with electron configuration, 1s ^twoiis ²iip ⁶ .

Exercise \(\PageIndex{1}\)

Write the electron configuration of oxygen atom (Z=8). How many electrons must O lose/gain to attain octet? Write the formula of the resulting ion and its electron configuration.

Respond

The electron configuration of O atom is is ^twoiis ²twop ⁴ . The 2d crush has half-dozen electrons ( 2s ²2p ⁴) and needs ii electrons to accomplish octet. Oxygen will proceeds two electrons. The resulting anion is O²⁻ with electron configuration, is ²twos ²2p ^half-dozen .

In many cases, elements that belong to the same grouping (vertical column) on the periodic tabular array form ions with the same charge because they have the aforementioned number of valence electrons. Thus, the periodic table becomes a tool for remembering the charges on many ions. For example, all ions made from alkali metals, the first cavalcade on the periodic table, have a 1+ charge. Ions made from alkaline earth metals, the 2d group on the periodic table, accept a ii+ accuse. On the other side of the periodic table, the side by side-to-last column, the halogens, course ions having a one− charge. Figure \(\PageIndex{iii}\) shows how the charge on many ions can be predicted by the location of an element on the periodic tabular array. Notation the convention of first writing the number and so the sign on a multiply charged ion. The barium cation is written Ba^{two +}, not Ba^+two.

Figure \(\PageIndex{3}\): Predicting Ionic Charges. The charge that an atom acquires when information technology becomes an ion is related to the structure of the periodic table. Within a group (family) of elements, atoms course ions of a certain charge.

Example \(\PageIndex{2}\)

Which of these ions is not probable to form?

1. Mg⁺
2. Chiliad⁺

Solution

(a) Mg is in Group 2A and has two valence electrons. It achieves octet by losing two electrons to form Mg^{2 +} cation. Losing only one electron to course Mg⁺ does non make an octet, hence, Mg⁺ is non probable to form.

Exercise \(\PageIndex{two}\)

Which of these ions is non probable to form?

1. S³⁻
2. N^three−

Answer

(a) Southward is in Group 6A and has six valence electrons. It achieves octet past gaining ii electrons to form Due south²⁻ anion. Gaining iii electrons to form Southward³⁻ does not brand it octet, hence, S^three− is non likely to form.

Lewis Diagrams

Chemists employ simple diagrams to prove an atom's valence electrons and how they transfer. These diagrams have 2 advantages over the electron trounce diagrams. Kickoff, they show just valence electrons. Second, instead of having a circle around the chemic symbol to correspond the electron shell, they accept up to viii dots around the symbol; each dot represents a valence electron. These dots are arranged to the right and left and above and beneath the symbol, with no more than than 2 dots on a side. For instance, the representation for sodium is as follows:

and the representation for chlorine is as follows:

For the higher up diagrams, information technology does not matter what sides the dots are placed on in Lewis diagrams every bit long as each side has a maximum of two dots.

These diagrams are called Lewis electron dot diagrams, or only Lewis diagrams, after Gilbert Due north. Lewis, the American pharmacist who introduced them. To write an element's Lewis dot symbol, identify the dots representing its valence electrons, i at a time, around the element'south chemical symbol. Up to 4 dots are placed above, beneath, to the left, and to the right of the symbol (in whatsoever social club, every bit long as elements with four or fewer valence electrons accept no more than 1 dot in each position). The next dots, for elements with more than iv valence electrons, are again distributed ane at a time, each paired with i of the start iv. In other words, identify the dots singly on each side before pairing them. The Lewis electron dot diagram of fluorine, for example, with seven valence electrons, is constructed as follows:

Figure \(\PageIndex{iv}\) shows the electron configurations and Lewis diagrams of the elements lithium through neon, which is the entire 2nd menses of the periodic tabular array. For the main group elements, the number of valence electrons is the aforementioned every bit the group number listed at the elevation of the periodic table.

Effigy \(\PageIndex{4}\): Lewis Electron Dot Diagrams of the Elements Lithium through Neon

The transfer of electrons can be illustrated easily with Lewis diagrams:

In representing the last formula, the dots are omitted.

Example \(\PageIndex{3}\)

Starting with lithium and bromine atoms, apply Lewis diagrams to testify the formation of the ionic compound LiBr.

Solution

From the periodic tabular array, we see that lithium is in the same column equally sodium, and then information technology will have the same valence shell electron configuration. That means that the neutral lithium atom will take the same Lewis diagram that the sodium atom has. Similarly, bromine is in the same cavalcade equally chlorine, so it will have the aforementioned Lewis diagram that chlorine has. Therefore,

Practise \(\PageIndex{iii}\)

Starting with magnesium and oxygen atoms, use Lewis diagrams to show the germination of the ionic chemical compound MgO.

Answer

Some ionic compounds have different numbers of cations and anions. In those cases, electron transfer occurs between more than than one cantlet. For instance, here is the germination of MgBr₂:

Notice that in this example there are two bromide ions (ane– charge) needed for every one magnesium ion (two+ accuse) in order for the overall charge of the compound to equal nil. This is called charge balance. The number of each type of ion is indicated in the formula by the subscript.

About of the elements that make ionic compounds form an ion that has a characteristic charge. For example, sodium makes ionic compounds in which the sodium ion always has a 1+ charge. Chlorine makes ionic compounds in which the chloride ion ever has a 1− charge. Some elements, especially transition metals, can form ions of multiple charges. Figure \(\PageIndex{five}\) shows the feature charges for some of these ions. As we saw in Figure \(\PageIndex{1}\), there is a blueprint to the charges on many of the primary grouping ions, simply there is no elementary design for transition element ions (or for the larger main grouping elements).

Figure \(\PageIndex{5}\): Charges of the Monatomic Ions. Note that some atoms commonly grade ions of variable charges.

Fundamental Takeaways

• Ions can be positively charged or negatively charged.
• A Lewis diagram is used to show how electrons are transferred to brand ions and ionic compounds.

Exercises

1. What are the two types of ions?
2. Utilize Lewis diagrams to illustrate the formation of an ionic compound from a potassium atom and an iodine atom.

3. When the following atoms go ions, what charges do they acquire?

1. Li
2. Southward
3. Ca
4. F

4. Identify each as a cation, an anion, or neither.

1. H⁺
2. Cl⁻
3. O₂
4. Ba^{ii +}
5. CH₄
6. CS_ii

5. Identify each every bit a cation, an anion, or neither.

1. NH₃
2. Br⁻
3. H⁻
4. Hg^{two +}
5. CCl_four
6. SO₃

vi. Write the electron configuration for each ion.

1. Li⁺
2. Mg^{2 +}
3. F⁻
4. S²⁻

7. Write the electron configuration for each ion.

1. Na⁺
2. Exist^{2 +}
3. Cl⁻
4. O²⁻

8. Draw Lewis diagrams for the ions listed in Exercise 6. Likewise include Lewis diagrams for the corresponding neutral atoms as a comparison.

9. Draw Lewis diagrams for the ions listed in Exercise 7. Also include Lewis diagrams for the respective neutral atoms as a comparison.

10. Using Lewis diagrams, show the electron transfer for the formation of LiF.

11. Using Lewis diagrams, testify the electron transfer for the formation of MgO.

12. Using Lewis diagrams, show the electron transfer for the formation of Li₂O.

xiii. Using Lewis diagrams, evidence the electron transfer for the germination of CaF₂.

14. What feature accuse do atoms in the starting time cavalcade of the periodic table take when they become ions?

15. What feature charge practice atoms in the second column of the periodic table take when they go ions?

16. What feature charge do atoms in the third-to-last column of the periodic tabular array have when they get ions?

17. What characteristic charge do atoms in the next-to-concluding column of the periodic table have when they go ions?

Answers

1. Cations (positive charged) and anions (negative charged).
2. 
3. 1. 1+
   2. two−
   3. 2+
   4. ane−

iv.

1. cation
2. anion
3. neither
4. cation
5. neither
6. neither

5.

1. neither
2. anion
3. anion
4. cation
5. neither
6. neither

6.

1. 1s ²
2. isouthward ^twotwos ²iip ⁶
3. ones ^twoiis ²2p ⁶
4. 1southward ²iis ⁱⁱ2p ^six3southward ²threep ^vi

7.

1. 1south ^two2due south ²twop ⁶
2. anes ²
3. is ²twos ²2p ⁶threes ²3p ^{half dozen}
4. 1s ²2southward ²iip ^six

8.

1. 

b.

c.

d.

9. ​ 10. eleven. 12. thirteen.

14. 1+

15. ii+

xvi. 2−

17. 1−

What Charge Does Chlorine Have,

Source: https://chem.libretexts.org/Courses/can/health/03%3A_Ionic_Bonding_and_Simple_Ionic_Compounds/3.3%3A_Ions

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