Name: predicting ion charges on the periodic table
Uploaded: 2020-09-03T13:38:25.000Z
Duration: 3 min 27 s
Channel: JoVE

K12 Standards

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North Carolina K-12 Science Standard Course of Study

9-12

Physical Science

Matter and its Interactions

PS.PSc.1.5

Ions and Ionic Charges

Atoms are neutral particles with equal numbers of protons and electrons. An element is defined by the number of protons, which does not change; however, many atoms can gain or lose one or more electrons to become a charged particle.

When an atom or molecule gains or loses electrons, it is called an ion. Electrons, being much smaller in mass than protons, do not contribute significantly to the atomic mass. Therefore, the atomic mass of an ion is essentially the same as the neutral atom&rsquo;s atomic mass.

When atoms or molecules lose electrons, they are called cations. Cations have a positive charge because they have more protons, which have a positive charge, than electrons, which have a negative charge. Cations are given the same name as their element, followed by the word ion.

A calcium atom has 20 protons and 20 electrons. It loses two electrons to become a &nbsp;calcium ion with 20 protons and 18 electrons. &nbsp;Because it now has two more positive charges than negative charges, it has an overall charge of positive two.&nbsp;

The chemical symbol for an ion is written as the chemical symbol of the atom with the charge written on the right superscript position. The chemical symbol for a calcium ion is therefore written as Ca2+.

When atoms or molecules gain electrons, they are called anions. Anions have a negative charge because they have more electrons than protons. Anions are named by adding the suffix &#39;-ide&#39; to their element name.

A fluorine atom has 9 protons and 9 electrons. Fluorine gains one electron to become a fluoride ion with 9 protons and 10 electrons. Because it now has one more negative charge than positive charges, it has an overall charge of negative one.

The chemical symbol for fluoride is written as F&minus;. &nbsp;The one is usually omitted for ions with a positive or negative one charge.

Atoms will lose or gain specific numbers of electrons when forming an ion. Many of the charges for ions formed by the main group elements can be predicted using the periodic table.&nbsp;

The metals, on the left side of the periodic table, will lose electrons. Group 1 alkali metals all lose one electron and have a positive one charge when they become an ion. Group 2 alkaline earth metals lose two electrons and have a positive two charge.&nbsp;

The nonmetals, on the right side of the periodic table, will gain electrons.&nbsp;Group 17 halogens gain one electron and have a negative one charge. Groups 16 elements gain two electrons and will have a negative two charge.

Many transition metals can form cations with different charges. Group 18 noble gases do not generally form ions.

ions and ionic charges

In ordinary chemical reactions, the nucleus &mdash; which contains the protons and neutrons of each atom and thus identifies the element &mdash; remains unchanged. Electrons, however, can be added to atoms by transfer from other atoms, lost by transfer to other atoms, or shared with other atoms. The transfer and sharing of electrons among atoms govern the chemistry of the elements. During the formation of some compounds, atoms gain or lose electrons to form electrically charged particles called ions.

When an atom loses electrons, it forms a positive ion called a cation. Cations have more protons than electrons. Likewise, when an atom gains electrons, it forms a negative ion called an anion. Anions have more electrons than protons.

The periodic table helps to predict whether an atom will form an anion or a cation, and also the charge of the resulting ion. Moving from the far left to the right on the periodic table, atoms of main-group metals lose enough electrons to leave them with the same number of electrons as an atom of the preceding noble gas. They form cations with a charge equal to the group number. To illustrate, an atom of an alkali metal (Group 1) loses one electron and forms a cation with a 1+ charge; an alkaline earth metal (Group 2) loses two electrons and forms a cation with a 2+ charge, and so on. For example, a neutral calcium atom, with 20 protons and 20 electrons, readily loses two electrons. This results in a cation with 20 protons, 18 electrons, and a 2+ charge. It has the same number of electrons as atoms of the preceding noble gas, argon, and is symbolized Ca2+. The name of a metal ion is the same as the name of the metal atom from which it forms, so Ca2+ is called a calcium ion.

Moving from the far right to the left on the periodic table, &nbsp;atoms of nonmetal elements generally gain enough electrons to give them the same number of electrons as an atom of the next noble gas in the periodic table. They form anions with a negative charge equal to the number of groups moved left from the noble gases. For example, atoms of group 17 elements (one group left of the noble gases) &nbsp;gain one electron and form anions with a 1&minus; charge; atoms of group 16 elements (two groups left) gain two electrons and form ions with a 2&minus; charge, and so on. For example, the neutral bromine atom, with 35 protons and 35 electrons, can gain one electron to provide it with 36 electrons. This results in an anion with 35 protons, 36 electrons, and a 1&minus; charge. It has the same number of electrons as atoms of the next noble gas, krypton, and is symbolized Br&minus;.

The trend between the charge of the ion and position of the group on the periodic table can be used as a guide in many cases. However, its predictive value decreases when moving toward the center of the periodic table. Transition metals and some other metals often exhibit variable charges that are not predictable by their location in the table. For example, copper can form ions with a 1+ or 2+ charge, and iron can form ions with a 2+ or 3+ charge.

This text is adapted from <a href="https://openstax.org/books/chemistry-2e/pages/2-6-molecular-and-ionic-compounds">Openstax, Chemistry 2e, Section 2.6: Molecular and Ionic Compounds</a>.

In ordinary chemical reactions, the nucleus &mdash; which contains the protons and neutrons of each atom and thus identifies the element &mdash; remains ...

Education

JoVE Core

Chemistry

Atoms and Elements

KEY TERMS AND CONCEPTS

predicting ion charges on the periodic table

Ion charges can often be predicted from an element’s position on the periodic table. In chemical reactions, the nucleus stays unchanged, but electrons may be transferred, lost, or shared. When atoms gain or lose electrons during compound formation, they become ions, which are electrically charged particles.

A positive ion is called a cation. A cation has more protons than electrons because it lost electrons. A negative ion is called an anion. An anion has more electrons than protons because it gained electrons.

The periodic table gives useful clues about ion charge. Main-group metals on the far left usually lose electrons until they have the same number of electrons as the preceding noble gas. Their cation charge often matches the group number. For example, a Group 1 alkali metal forms a 1+ cation, and a Group 2 alkaline earth metal forms a 2+ cation.

Calcium shows this pattern clearly. A neutral calcium atom has 20 protons and 20 electrons. It can lose two electrons to form Ca2+, which has 20 protons, 18 electrons, and a 2+ charge. This ion has the same number of electrons as argon. The name of the metal ion is the same as the metal atom, so Ca2+ is called a calcium ion.

Nonmetals on the far right usually gain electrons to reach the electron count of the next noble gas. Their anion charge often matches how many groups they are away from the noble gases. Group 17 elements usually gain one electron to form 1− anions, and Group 16 elements usually gain two electrons to form 2− anions.

Bromine is one example. A neutral bromine atom has 35 protons and 35 electrons. It can gain one electron to form Br− with 35 protons, 36 electrons, and a 1− charge. This ion has the same number of electrons as krypton. The trend between group position and ion charge helps in many cases, but it becomes less reliable near the center of the periodic table. Transition metals and some other metals often have variable charges. Copper can form 1+ or 2+ ions, and iron can form 2+ or 3+ ions.

Predicting Ion Charges on the Periodic Table

predicting-ion-charges-on-the-periodic-table

the atomic theory of matter

Dalton’s Laws and Early Atomic Ideas

Dalton’s atomic theory explains matter with atoms, elements, and compounds. It also shows how chemical changes follow simple laws. This idea gave chemistry a microscopic model for what can be seen in the lab. The earliest recorded ideas about matter came from ancient Greek philosophers. Leucippus and Democritus said all matter was made of tiny, finite particles called atomos, meaning “indivisible.” Aristotle and others later argued that matter was made from four elements: fire, earth, air, and...

subatomic particles

Atomic Structure: Protons, Neutrons, and Electrons

Atomic structure is built from three subatomic particles: protons, neutrons, and electrons. Atoms make up all matter, and these particles explain an atom’s mass and charge. The electron was first identified at the end of the 19th century by J.J. Thomson. He used a cathode ray tube, a sealed glass tube with almost all the air removed and two metal electrodes. When high voltage was applied, a visible beam called a cathode ray formed. The beam bent toward positive charge and away from negative...

elements: chemical symbols and isotopes

Reading Element Symbols and Isotope Notation

Chemical symbols and isotope notation help identify elements and their atoms. A chemical symbol is an abbreviation for an element or a single atom of that element. Mercury, for example, is written as Hg. The same symbol can point to one atom in the microscopic domain or to many atoms of the element in a container or sample. Many symbols come from the element’s common English name. Others come from Latin, Greek, or German names. Aluminum uses Al, while iron uses Fe from the Latin word Ferrum.

Ion charges can often be predicted from an element’s position on the periodic table. In chemical reactions, the nucleus stays unchanged, but electrons may be transferred, lost, or shared. When atoms gain or lose electrons during compound formation, they become ions, which are electrically charged particles. A positive ion is called a cation. A cation has more protons than electrons because it lost electrons. A negative ion is called an anion. An anion has more electrons than protons because it...

the periodic table

Periodic Table Patterns and Element Groups

The periodic table organizes elements by repeating patterns in their properties. Chemists first noticed that some elements behaved alike, so they grouped them by chemical behavior. Lithium, sodium, and potassium are one example. They are shiny and conduct heat and electricity well. Calcium, strontium, and barium form another group with similar physical and chemical properties. Yet these two groups are not the same. The lithium group is much more reactive, and its elements form oxygen compounds...

atomic mass

Average Atomic Mass and Isotopes

Average atomic mass explains why many elements on the periodic table have decimal values. Atoms are extremely small, so scientists use the atomic mass unit, or amu, to measure them. A carbon atom weighs less than 2 × 10−23 g, and the amu is defined from carbon-12. One amu is exactly 1/12 the mass of one carbon-12 atom, which is 1.6605 × 10−24 g. The dalton (Da) and the unified atomic mass unit (u) mean the same thing as the amu. For a single atom, atomic mass is usually close to its mass...

molar mass

Mole, Mass, and Avogadro’s Number

The mole links mass and the number of particles in a substance. It gives chemists a standard way to count atoms and molecules in samples that are far too small to see. It also helps show why substances with the same kinds of atoms can still have very different properties, like water, H2O, and hydrogen peroxide, H2O2. The mole is an amount unit, like a pair or a dozen. One mole contains 6.02214076 × 10^23 discrete entities, such as atoms or molecules. This number is usually rounded to 6.022 ×...

key terms and concepts

Learn how the periodic table helps predict cation and anion charges, with examples like calcium, bromine, copper, and iron for grades 9–12.

Predicting Ion Charges on the Periodic Table | JoVE K12

chemistry

JoVE Core Chemistry brings general chemistry concepts to life using concise and easy-to-understand animated video lessons. Plus, in the scientist-in-action videos, we demonstrate classical and original research experiments performed in today's laboratories worldwide.

Louisiana Student Standards for Science

High School

Matter And Its Interactions

HS-PS1-1

motion-and-stability-forces-and-interactions

Motion And Stability: Forces And Interactions

HS-PS2-6

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Ohio’s Learning Standards and Model Curriculum

Study Of Matter

Atoms

Tennessee Academic Standards

Matter and Its Interactions

CHEM1.PS1.13

Virginia  Standards of Learning

HIgh School

CH.2

CH.2.a

PS.4

PS.4.a

Arizona Science Standards

HS+C.P1

HS+C.P1U1.1

HS.P1

HS.P1U1.2

Alabama Course of Study Science

9-12.C.1.1.a

9-12.C.1.1.b

9-12.PS.3.4

9-12.PS.3.4.d

Florida Department of Education

SC.912.P.8

SC.912.P.8.4

Texas Essential Knowledge and Skills

Chemistry and Physics

IPC.7

IPC.7.A

Georgia Standards of Excellence

SPS1.

Properties of Atoms, Ions, and Isotopes

Classifying Matter by State

Chemistry is the study of matter and the changes it undergoes. Matter is anything that has mass and occupies space. Matter is all around us; the air, ...

Classifying Matter by Composition

Matter: Pure Substances and Mixtures
According to its composition, the matter can be classified into two broad categories &mdash; pure substances and ...

Elements: Chemical Symbols and Isotopes

A chemical symbol is an abbreviation used to indicate an element or an atom of an element. For example, the symbol for mercury is Hg. The same symbol is ...

Molecules and Compounds

Atoms and Molecules

Everything in the universe is made up of matter, and matter is composed of a combination of elements. An atom is the smallest unit of ...

Solution Formation

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Colloids

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Construct an explanation to classify matter as a pure substance or mixture; homogeneous or heterogeneous; element or compound; solution, colloid or suspension.

PS.PSc.1.1

Phase Transitions

Whether solid, liquid, or gas, a substance&#39;s state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the ...

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Phase Transitions: Vaporization and Condensation

The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize ...

Vapor Pressure

When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules move randomly about, they will occasionally ...

Clausius-Clapeyron Equation

The equilibrium between a liquid and its vapor depends on the temperature of the system; a rise in temperature causes a corresponding rise in the vapor ...

Phase Transitions: Melting and Freezing

Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy ...

phase-transitions-sublimation-and-deposition

Phase Transitions: Sublimation and Deposition

Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and ...

Heating and Cooling Curves

When a substance&#8212;isolated from its environment&#8212;is subjected to heat changes, corresponding changes in temperature and phase of the substance ...

Phase Diagrams

A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. ...

Use models to compare the phases of matter and the physical changes they undergo.

PS.PSc.1.2

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Physical and Chemical Properties of Matter

The characteristics that enable us to distinguish one substance from another are called properties.

Physical Properties of Matter

A physical property is ...

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Molecular Comparison of Gases, Liquids, and Solids

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Intermolecular vs Intramolecular Forces

Intermolecular forces (IMF) are electrostatic attractions arising from charge-charge interactions between molecules. The strength of the intermolecular ...

Intermolecular Forces

Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions ...

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Comparing Intermolecular Forces: Melting Point, Boiling Point, and Miscibility

Intermolecular forces are attractive forces that exist between molecules. They dictate several bulk properties, such as melting points, boiling points, ...

Carry out investigations to compare physical and chemical properties of matter.

PS.PSc.1.3

The Atomic Theory of Matter

The earliest recorded discussion of the basic structure of matter comes from ancient Greek philosophers. Leucippus and Democritus argued that all matter ...

Subatomic Particles

Dalton was only partially correct about the particles that make up matter. All matter is composed of atoms, and atoms are composed of three smaller ...

The Bohr Model

Following the work of Ernest Rutherford and his colleagues in the early twentieth century, the picture of atoms consisting of tiny dense nuclei surrounded ...

Emission Spectra

When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a ...

The de Broglie Wavelength

In the macroscopic world, objects that are large enough to be seen by the naked eye follow the rules of classical physics. A billiard ball moving on a ...

The Uncertainty Principle

Werner Heisenberg considered the limits of how accurately one can measure properties of an electron or other microscopic particles. He determined that ...

Use models to interpret the data presented in Bohr diagrams and electron dot diagrams for neutral atoms of elements 1 through 18.

PS.PSc.1.4

Use models to compare representations of atoms, ions, and isotopes.

The Periodic Table

As early chemists discovered more elements, they realized that various elements could be grouped by their similar chemical behaviors. One such grouping ...

Periodic Classification of the Elements

The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their ...

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Atomic Radii and Effective Nuclear Charge

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Ionic Radii

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Ionization Energy

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Electron Affinity

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This process can be either ...

Alkali Metals

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Halogens

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Noble Gases


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PS.PSc.1.6

Types of Chemical Bonds

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Ionic Bonding and Electron Transfer

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Covalent Bonding and Lewis Structures

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Bonding in Metals

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Construct an explanation to classify the type of chemical bond that occurs (covalent, ionic, or metallic) in a given substance.

PS.PSc.2.1

Nomenclature of Alkanes

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Nomenclature of Alkenes

The IUPAC naming system for alkenes replaces -an- with -en- in the corresponding parent alkanes. Accordingly, a simple alkene replaces the -ane suffix of ...

Nomenclature of Alkynes

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structure-and-nomenclature-of-alcohols-and-phenols

Structure and Nomenclature of Alcohols and Phenols

Overview 
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Structure and Nomenclature of Ethers

Structure and Bonding
Ethers are organic compounds with an ether functional group which is characterized by an oxygen atom connected to two &#8212; ...

IUPAC Nomenclature of Aldehydes

Aldehydes are named based on the systematic nomenclature rules set by the IUPAC. For acyclic aldehydes, the longest carbon chain containing the aldehydic ...

IUPAC Nomenclature of Ketones

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IUPAC Nomenclature of Carboxylic Acids

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Nomenclature of Aromatic Compounds with a Single Substituent

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Nomenclature of Aromatic Compounds with Multiple Substituents

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For disubstituted ...

Use models to apply International Union of Pure and Applied Chemistry (IUPAC) conventions to name and write formulas for simple compounds.

PS.PSc.2.2

Understand types, properties, and structure of matter.

Predicting Ion Charges on the Periodic Table

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