Chemistry
Ions: Anions and Cations
Ions are charged particles formed when atoms gain or lose electrons. Anions are negatively charged ions formed when an atom gains electrons, while cations are positively charged ions formed when an atom loses electrons. These charged ions play a crucial role in chemical reactions and the behavior of substances in various environments.
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10 Key excerpts on "Ions: Anions and Cations"
eBook - PDF- Rose Marie O. Mendoza(Author)
- 2023(Publication Date)
- Arcler Press(Publisher)
INTRODUCTION TO IONS AND IONIC COMPOUNDS 1 CONTENTS 1.1. Introduction ........................................................................................ 2 1.2. Ions and the Periodic Table ................................................................. 5 1.3. Ionic Bonding ................................................................................... 10 1.4. Practice Writing Correct Ionic Formulas ............................................ 13 1.5. Naming Ions and Ionic Compounds.................................................. 15 1.6. Polyatomic Ions ................................................................................ 17 1.7. Properties and Formation of Ionic Compounds ................................. 23 1.8. Arrhenius Acids and Bases and Their Role in Salt Formation ............. 24 1.9. Ions, Neurons, and Neuron Impulses ................................................ 25 1.10. Chapter Summary ........................................................................... 34 References ............................................................................................... 37 CHAPTER The Study of Ions and Salts in Chemistry 2 1.1. INTRODUCTION By definition, an atom is considered neutral because the total number of electrons (charged negatively) is the same as the total number of protons (positively charged particle). Since the number of negatively charged particles is equivalent to the number of the positively charged patricles, the total charge on the atom is zero (0). However, this one-to-one charge ratio is not the most frequent condition for a large number of elements. Disorders, therefore, in ratio result in the formation of charged particles termed ions (Koppenol, 2002; Poulsen, 2010; Ball et al., 2011). Across nature, high- energy objects flow to lesser-energy positions.. These lesser energy variables are exemplified as noble gas components in terms of atoms.
eBook - PDF- Morris Hein, Susan Arena, Cary Willard(Authors)
- 2021(Publication Date)
- Wiley(Publisher)
An ionic bond is the attraction between oppositely charged ions. Ionic bonds are formed whenever one or more electrons are transferred from one atom to another. Metals, which have relatively little attraction for their valence electrons, tend to form ionic bonds when they combine with nonmetals. It’s important to recognize that substances with ionic bonds do not exist as molecules. In sodium chloride, for example, the bond does not exist solely between a single sodium ion and a single chloride ion. Each sodium ion in the crystal attracts six near-neighbor negative chloride ions; in turn, each negative chloride ion attracts six near-neighbor positive sodium ions (see Figure 11.4). A metal will usually have one, two, or three electrons in its outer energy level. In react- ing, metal atoms characteristically lose these electrons, attain the electron structure of a noble gas, and become positive ions. A nonmetal, on the other hand, is only a few electrons short of having a noble gas electron structure in its outer energy level and thus has a ten- dency to gain electrons. In reacting with metals, nonmetal atoms characteristically gain one to four electrons, attain the electron structure of a noble gas, and become negative ions. The ions formed by loss of electrons are much smaller than the corresponding metal atoms; the ions formed by gaining electrons are larger than the corresponding nonmetal atoms. The dimensions of the atomic and ionic radii of several metals and nonmetals are given in Table 11.3. Note A cation is always smaller than its parent atom, whereas an anion is always larger than its parent atom.
eBook - ePub- John T. Moore(Author)
- 2016(Publication Date)
- For Dummies(Publisher)
+ represents its net positive electrical charge).This unequal number of negative and positive charges can occur in one of two ways: An atom can gain a proton (a positive charge) or lose an electron (a negative charge). So which process is more likely to occur? Well, the rough guideline is that gaining or losing electrons is easy but gaining or losing protons is very difficult. So atoms become ions by gaining or losing electrons.If an ion is formed by the loss of an electron, the ion has more protons than electrons, or more positive charges. Those positive ions are called cations. You represent the overall positive charge in cations with the little plus sign in the notation (like Na+ ). If the atom loses two electrons instead of one, the result is still a cation, but it has a stronger positive charge (actually twice as strong as in the case in which only one electron was lost) and is represented with the number of electrons lost and a plus sign (like Mg2+ for a magnesium cation with two missing electrons, or Al3+ for aluminum with three electrons gone).If an ion is created by gaining an electron, the number of electrons exceeds the number of protons, so the ion acquires a negative charge. Negatively charged ions are called anions, and they’re represented with a little negative sign (– ). If chlorine (Cl) gains an electron, it becomes a chlorine ion because it has unequal numbers of protons and electrons, and as an anion (a negatively charged ion), it’s represented as Cl– . (You can get the full scoop on ions, cations, and anions in Chapter 13 , if you’re interested. This here’s just a teaser.)Just for kicks, here are some extra tidbits about ions for your reading pleasure:- You can write electron configurations and energy-level diagrams for ions. The neutral sodium atom (11 protons) has an electron configuration of 1s2 2s2 2p6 3s1 . The sodium cation has lost an electron — the valence electron, which is farthest away from the nucleus (the 3s electron, in this case). The electron configuration of Na+ is 1s2 2s2 2p6
eBook - PDF- Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson(Authors)
- 2019(Publication Date)
- Openstax(Publisher)
When electrons are transferred and ions form, ionic bonds result. Ionic bonds are electrostatic forces of attraction, that is, the attractive forces experienced between objects of opposite electrical charge (in this case, cations and anions). When electrons are “shared” and molecules form, covalent bonds result. Covalent bonds are the attractive forces between the positively charged nuclei of the bonded atoms and one or more pairs of electrons that are located between the atoms. Compounds are classified as ionic or molecular (covalent) on the basis of the bonds present in them. 92 2 • Atoms, Molecules, and Ions Access for free at openstax.org Ionic Compounds When an element composed of atoms that readily lose electrons (a metal) reacts with an element composed of atoms that readily gain electrons (a nonmetal), a transfer of electrons usually occurs, producing ions. The compound formed by this transfer is stabilized by the electrostatic attractions (ionic bonds) between the ions of opposite charge present in the compound. For example, when each sodium atom in a sample of sodium metal (group 1) gives up one electron to form a sodium cation, Na + , and each chlorine atom in a sample of chlorine gas (group 17) accepts one electron to form a chloride anion, Cl − , the resulting compound, NaCl, is composed of sodium ions and chloride ions in the ratio of one Na + ion for each Cl − ion. Similarly, each calcium atom (group 2) can give up two electrons and transfer one to each of two chlorine atoms to form CaCl 2 , which is composed of Ca 2+ and Cl − ions in the ratio of one Ca 2+ ion to two Cl − ions. A compound that contains ions and is held together by ionic bonds is called an ionic compound. The periodic table can help us recognize many of the compounds that are ionic: When a metal is combined with one or more nonmetals, the compound is usually ionic.
eBook - PDF- Leo J. Malone, Theodore O. Dolter(Authors)
- 2012(Publication Date)
- Wiley(Publisher)
Transition metals also form positive ions, but for the most part these ions do not relate to a noble gas configuration. Some of these ions were discussed in Chapter 4. 280 CHAPTER 9 The Chemical Bond where all four of their outer electrons are involved, but the bonding in these compounds is best described by electron sharing rather than ion formation. For the most part, Group IVA nonmetals also bond by electron sharing rather than forming monatomic ions. Although there is some evidence for a C 4- ion with an octet of electrons, formation of such highly charged ions is an energetically unfavorable process. In Group VA, bismuth forms a +3 ion that does not follow the octet rule. 9-2.3 The Physical State of Ionic Compounds Much of the solid, hard surface of our Earth is composed of ionic compounds that tend to have high melting points and are usually hard and brittle. If we look into the basic structure of a crystal of table salt, we can see why. Ionic compounds do not exist as discrete molecular units with one Na + attached to one Cl - . As shown in Figure 9-2, each Na + is actually surrounded by six Cl - ions, and each Cl − ion is surrounded by six Na + ions in a three-dimensional array of ions called a lattice. Recall from Chapter 8 that cations are smaller than their parent atoms, whereas anions are larger. Thus, in most cases we can assume that the anion is larger than the cation. The lattice is held together strongly and rigidly by electrostatic interactions. These electrostatic attractions are known as ionic bonds. There are several other arrays of ions (lattices) used to accommodate both the size differences and varying ratios of cat- ions to anions found in all of the possible ionic compounds. For example, in CsCl both the Cs + and the Cl - are surrounded by eight oppositely charged ions.
eBook - PDF- Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson(Authors)
- 2015(Publication Date)
- Openstax(Publisher)
When electrons are “shared” and molecules form, covalent bonds result. Covalent bonds are the attractive forces between the positively charged nuclei of the bonded atoms and one or more pairs of electrons that are located between the atoms. Compounds are classified as ionic or molecular (covalent) on the basis of the bonds present in them. Ionic Compounds When an element composed of atoms that readily lose electrons (a metal) reacts with an element composed of atoms that readily gain electrons (a nonmetal), a transfer of electrons usually occurs, producing ions. The compound formed by this transfer is stabilized by the electrostatic attractions (ionic bonds) between the ions of opposite charge present in the compound. For example, when each sodium atom in a sample of sodium metal (group 1) gives up one electron to form a sodium cation, Na + , and each chlorine atom in a sample of chlorine gas (group 17) accepts one electron to form a chloride anion, Cl − , the resulting compound, NaCl, is composed of sodium ions and chloride ions in the ratio Chapter 2 | Atoms, Molecules, and Ions 101 of one Na + ion for each Cl − ion. Similarly, each calcium atom (group 2) can give up two electrons and transfer one to each of two chlorine atoms to form CaCl 2 , which is composed of Ca 2+ and Cl − ions in the ratio of one Ca 2+ ion to two Cl − ions. A compound that contains ions and is held together by ionic bonds is called an ionic compound. The periodic table can help us recognize many of the compounds that are ionic: When a metal is combined with one or more nonmetals, the compound is usually ionic. This guideline works well for predicting ionic compound formation for most of the compounds typically encountered in an introductory chemistry course. However, it is not always true (for example, aluminum chloride, AlCl 3 , is not ionic). You can often recognize ionic compounds because of their properties.
- Morris Hein, Scott Pattison, Susan Arena, Leo R. Best(Authors)
- 2014(Publication Date)
- Wiley(Publisher)
11.4 PREDICTING FORMULAS OF IONIC COMPOUNDS • Chemical compounds are always electrically neutral. • Metals lose electrons and nonmetals gain electrons to form compounds. • Stability is achieved (for representative elements) by attaining a noble gas electron configuration. 11.5 THE COVALENT BOND: SHARING ELECTRONS • Covalent bonds are formed when two atoms share a pair of electrons between them: • This is the predominant type of bonding in compounds. • True molecules exist in covalent compounds. • Overlap of orbitals forms a covalent bond. • Unequal sharing of electrons results in a polar covalent bond. 11.6 ELECTRONEGATIVITY • Electronegativity is the attractive force an atom has for shared electrons in a molecule or polyatomic ion. • Electrons spend more time closer to the more electronegative atom in a bond forming a polar bond. • The polarity of a bond is determined by the electronegativity difference between the atoms involved in the bond: • The greater the difference, the more polar the bond is. • At the extremes: • Large differences result in ionic bonds. • Tiny differences (or no difference) result(s) in a nonpolar covalent bond. C H A P T E R 1 1 R E V I E W KEY TERM ionization energy KEY TERM Lewis structure KEY TERM ionic bond KEY TERMS covalent bond polar covalent bond KEY TERMS electronegativity nonpolar covalent bond dipole 240 CHAPTER 11 • Chemical Bonds: The Formation of Compounds from Atoms • A molecule that is electrically asymmetrical has a dipole, resulting in charged areas within the molecule. −δ +δ H : Cl H Cl � � � � hydrogen chloride • If the electronegativity difference between two bonded atoms is greater than 1.7–1.9, the bond will be more ionic than covalent. • Polar bonds do not always result in polar molecules. 11.7 LEWIS STRUCTURES OF COMPOUNDS PROBLEM-SOLVING STRATEGY: Writing a Lewis Structure 1.
eBook - PDF- Stanley E. Manahan(Author)
- 2009(Publication Date)
- CRC Press(Publisher)
The overall process is shown by the vertical arrow in the middle and the constituent parts by the arrows around the periphery. by the arrows around the periphery. 148 Fundamentals of Sustainable Chemical Science 148 Fundamentals of Sustainable Chemical Science by the lattice energy are greater. Because of the removal of their outer shell electrons, by the lattice energy are greater. Because of the removal of their outer shell electrons, cations are smaller than the atoms from which they are formed; because of the addi-cations are smaller than the atoms from which they are formed; because of the addi-tion of outer shell electrons, anions are larger than their corresponding neutral atoms. tion of outer shell electrons, anions are larger than their corresponding neutral atoms. Some ion sizes are shown in Figure 4.7. This figure shows some trends in ion size Some ion sizes are shown in Figure 4.7. This figure shows some trends in ion size across periods of the periodic table and within vertical groups in the table. In going across periods of the periodic table and within vertical groups in the table. In going from left to right across a period, it is seen that the cations decrease in size with from left to right across a period, it is seen that the cations decrease in size with Li + (68) Be 2+ (30) O 2– (145) F – (133) Na + (98) Mg 2+ (65) Al 3+ (45) S 2– (190) Cl – (181) K + (133) Ca 2+ (94) Sc 3+ (68) Se 2– (202) Br – (196) Rb + (148) Sr 2+ (110) I – (219) Cs + (167) Ba 2+ (131) Figure 4.7. Figure 4.7. Diameters of some ions formed from single atoms, in units of picometers Diameters of some ions formed from single atoms, in units of picometers (1 Ångstrom (1 Ångstrom 100 pm). 100 pm). Chemical Bonds, Molecules, and Compounds 149 Chemical Bonds, Molecules, and Compounds 149 increasing ionic charge. The size of cations within a period decreases significantly in increasing ionic charge.
eBook - PDFChemistry
Structure and Dynamics
- James N. Spencer, George M. Bodner, Lyman H. Rickard(Authors)
- 2011(Publication Date)
- Wiley(Publisher)
But positively charged Na ions are so unreactive with water they are essentially inert. Neutral chlorine atoms instantly combine to form Cl 2 molecules, which are so reactive that entire communities are evacuated when trains carrying chlorine gas derail. Negatively charged Cl ions are essentially inert to chemical reactions. The enormous difference between the chemistry of neutral atoms and their ions means that it is necessary to pay close attention to the symbols to make sure that atoms and ions are not confused with one another. E x e r c i s e 1 . 5 Find the number of protons, electrons, and neutrons in each of the following atoms and ions. (a) 24 Mg 2 (b) 79 Br Solution (a) The atomic number of magnesium is 12, which means that the nucleus of this ion contains 12 protons. Because the mass number of the ion is 24 and it contains 12 protons, the nucleus of the atom must contain 12 neu- trons. Because the ion carries a charge of 2, there must be two more pro- tons (positive charges) than electrons (negative charges). This ion therefore contains 10 electrons. (b) Bromine has an atomic number of 35, and there are therefore 35 protons in the nucleus of this ion. Because the mass number of the ion is 79 and it contains 35 protons, there must be 44 neutrons in the nucleus of the atom. Because the ion has a 1 charge, the ion must have one more electron than a neutral atom. This ion therefore contains 36 electrons. 1.11 Polyatomic Ions Simple ions, such as the Mg 2 and N 3 ions, are formed by adding or subtract- ing electrons from neutral atoms. Polyatomic ions are electrically charged mole- cules composed of more than one atom. You will commonly encounter only two polyatomic positive ions or cations. These are the ammonium and hydronium ions, NH 4 and H 3 O . A few of the more common negative ions or anions are listed in Table 1.6.
eBook - PDF- Bernard Moody(Author)
- 2013(Publication Date)
- Arnold(Publisher)
They are said to obey 'the octet rule'. However, there are certain other configurations which result from chemical combination and these will be described in their proper context. The ionic bond and the formation of ions In 1916, Kossel suggested that an atom acquired the electronic configuration of an inert gas by the loss or gain of electrons. The result is the formation of ions. This valency bond, which is an electrostatic attraction between ions, is called the ionic bond or electro valent bond. There is no molecule in the kinetic theory sense and during electrolysis of either the fused compound or solution, ions will migrate towards oppositely charged poles. Consider a hypothetical reaction between atoms of lithium and fluorine to form lithium fluoride.
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