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Below is a Quizlet of the three laws that govern how matter behaves in chemical reactions, so you can practice distinguishing them.

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The 3 Basic Laws that Describes How Matter Behaves in Chemical Reactions Flashcards | Quizlet

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Start studying The 3 Basic Laws that Describes How Matter Behaves in Chemical Reactions. Learn vocabulary, terms, and more with flashcards, games, and other study tools.

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Example of the Law of Conservation of Mass

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Example of the Law of Conservation of Mass

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Example of the Law of Definite Proportions

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Example of the Law of Definite Proportions

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Example of the Law of Multiple Proportions

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Example of the Law of Multiple Proportions

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Video on the Three Laws that Led to Modern Atomic Theory

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Video on the Three Laws that Led to Modern Atomic Theory

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Webpage that explains the main points of his theory

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The postulates of Dalton's atomic theory: which points do we still use today, and what have we learned since Dalton?

Dalton's atomic theory was the first complete attempt to describe all matter in terms of atoms and their properties.

Dalton based his theory on the law of conservation of mass and the law of constant composition.

The first part of his theory states that all matter is made of atoms, which are indivisible.

The second part of the theory says all atoms of a given element are identical in mass and properties.

The third part says compounds are combinations of two or more different types of atoms.

The fourth part of the theory states that a chemical reaction is a rearrangement of atoms.

Parts of the theory had to be modified based on the discovery of subatomic particles and isotopes.

Chemists ask questions.

Chemistry is full of unanswered questions. One of the first questions people have been asking since ancient times is What is the world made of?

That is, if we were to zoom in ~100000000000 times-that is 11 zeros!-on the skin of your fingertip, what would we see? Would that look any different from zooming in on, say, an apple? If we then cut up the apple into tinier and tinier pieces using an imaginary tiny knife, would we reach a point where the pieces could no longer be cut any smaller? What would those pieces look like, and would they still have apple properties?

The answers to these questions are fundamental to modern chemistry, and chemists didn't agree on the answer until a few hundred years ago. Thanks to scientists such as John Dalton, modern chemists think of the world in terms of atoms. Even if we can't see atoms with our naked eye, properties of matter such as color, phase (e.g., solid, liquid, gas), and even smell come from interactions on an atomic level. This article will discuss John Dalton's atomic theory, which was the first complete attempt to describe all matter in terms of atoms and their properties.

Basis for Dalton's theory

Dalton based his theory on two laws: the law of conservation of mass and the law of constant composition.

The law of conservation of mass says that matter is not created or destroyed in a closed system. That means if we have a chemical reaction, the amount of each element must be the same in the starting materials and the products. We use the law of conservation of mass every time we balance equations!

The law of constant composition says that a pure compound will always have the same proportion of the same elements. For example, table salt, which has the molecular formula , contains the same proportions of the elements sodium and chlorine no matter how much salt you have or where the salt came from. If we were to combine some sodium metal and chlorine gas-which I wouldn't recommend doing at home-we could make more table salt which will have the same composition.

Concept check: A time-travelling scientist from the early 1700s decides to run the following experiment: he takes a 10 gram sample of ethanol () and burns it in the presence of oxygen in an open beaker. After the reaction is done, the beaker is empty. Does this result violate the law of conservation of mass?

Dalton's atomic theory

Part 1: All matter is made of atoms.

Dalton hypothesized that the law of conservation of mass and the law of definite proportions could be explained using the idea of atoms. He proposed that all matter is made of tiny indivisible particles called atoms, which he imagined as "solid, massy, hard, impenetrable, movable particle(s)".

It is important to note that since Dalton did not have the necessary instruments to see or otherwise experiment on individual atoms, he did not have any insight into whether they might have any internal structure. We might visualize Dalton's atom as a piece in a molecular modeling kit, where different elements are spheres of different sizes and colors. While this is a handy model for some applications, we now know that atoms are far from being solid spheres.

Part 2: All atoms of a given element are identical in mass and properties.

Dalton proposed that every single atom of an element, such as gold, is the same as every other atom of that element. He also noted that the atoms of one element differ from the atoms of all other elements. Today, we still know this to be mostly true. A sodium atom is different from a carbon atom. Elements may share some similar boiling points, melting points, and electronegativities, but no two elements have the same exact set of properties.

Part 3: Compounds are combinations of two or more different types of atoms.

In the third part of Dalton's atomic theory, he proposed that compounds are combinations of two or more different types of atoms. An example of such a compound is table salt. Table salt is a combination of two separate elements with unique physical and chemical properties. The first, sodium, is a highly reactive metal. The second, chlorine, is a toxic gas. When they react, the atoms combine in a 1:1 ratio to form white crystals of , which we can sprinkle on our food.

Since atoms are indivisible, they will always combine in simple whole number ratios. Therefore, it would not make sense to write a formula such as because you can't have half of an atom!

Part 4: A chemical reaction is a rearrangement of atoms.

In the fourth and final part of Dalton's atomic theory, he suggested that chemical reactions don't destroy or create atoms. They merely rearranged the atoms. Using our salt example again, when sodium combines with chlorine to make salt, both the sodium and chlorine atoms still exist. They simply rearrange to form a new compound.

What have we learned since Dalton proposed his theory?

The short answer: a lot! For instance, we now know that atoms are not indivisible-as stated in part one-because they are made up of protons, neutrons, and electrons. The modern picture of an atom is very different from Dalton's "solid, massy" particle. In fact, experiments by Ernest Rutherford, Hans Geiger, and Ernest Marsden showed that atoms are mostly made up of empty space.

Part two of Dalton's theory had to be modified after mass spectrometry experiments demonstrated that atoms of the same element can have different masses because the number of neutrons can vary for different isotopes of the same element. For more on isotopes, you can watch this video on atomic number, mass number, and isotopes.

Despite these caveats, Dalton's atomic theory is still mostly true, and it forms the framework of modern chemistry. Scientists have even developed the technology to see the world on an atomic level!

Dalton's atomic theory was the first complete attempt to describe all matter in terms of atoms and their properties.

Dalton based his theory on the law of conservation of mass and the law of constant composition.

The first part of his theory states that all matter is made of atoms, which are indivisible.

The second part of the theory says all atoms of a given element are identical in mass and properties.

The third part says compounds are combinations of two or more different types of atoms.

The fourth part of the theory states that a chemical reaction is a rearrangement of atoms.

Parts of the theory had to be modified based on the existence of subatomic particles and isotopes.

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Dalton's atomic theory (article) | Khan Academy

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Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.

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Video about the History of Atomic Theory

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Video about the History of Atomic Theory

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This video provides a timeline of the scientists who made important discoveries involving atomic structure.

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The History of Atomic Chemistry: Crash Course Chemistry #37

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Protons, Neutrons, and Electrons (An Intro to Subatomic Particles)

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Learn the basics of the three subatomic particles: protons, neutrons, and electrons! In this video I'll go over some introductory ideas that every students needs to know about the subatomic particles of an atom. We'll go over charge first, because learning the charge of our three subatomic particles in chemistry is one of the most important facts we can learn about them.

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Compare and contrast protons, neutrons, and electrons

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Compare and contrast protons, neutrons, and electrons

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How to Use PowToon for the Atomic Theory Timeline Project 

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How to Use PowToon for the Atomic Theory Timeline Project 

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Click the link below, and scroll down to the video entitled "How to Use the PowToon Timeline."

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Free mini-courses show you the quickest way to make an awesome video like a pro in just a few minutes. Explore templates, timeline, scriptwriting, voiceovers, and more!

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Video showing Rutherford's Gold Foil Experiment

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Video showing Rutherford's Gold Foil Experiment

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Rutherford's Gold Foil Experiment - Quick and Simple!

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This is the simulation used in class, so feel free to experiment with it on your own as well!

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Atomic Number and Mass Number Example Problems

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Atomic Number and Mass Number Example Problems

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Related Topics:
More Lessons for Chemistry
Math Worksheets

The number of protons in the nucleus of an atom is called the atomic number.

It is represented by the symbol Z

Example:
Helium has an atomic number of 2 since it has two protons in its nucleus.
Lithium has an atomic number of 3 since it has three protons in its nucleus.

What is Mass number

The mass number is the total number of neutrons and protons in the nucleus of the atom.

It is also called the nucleon number.

It is represented by the symbol A

The atomic number and the mass number of an element is usually written in the following way:

The helium atom has a mass number of 4 and atomic number of 2

What is the mass number and atomic number of the ?
Solution:
Mass number = 31, atomic number = 15

Number of neutrons = mass number - atomic number
Example:
How many neutrons are there in one atom of ?
Solution:
Mass number = 24
Atomic number = 12
Number of neutrons = mass number - atomic number = 24 - 12 = 12
Example:
How many neutrons are there in one atom of ?
Solution:
Mass number = 307
Atomic number = 82
Number of neutrons = mass number - atomic number = 207 - 82 = 125

Atomic number, mass number, and isotopes
How to use the atomic number and the mass number to represent different isotopes

The following video shows an example of calculating the number of neutrons.

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Atomic Number & Mass Number (examples, solutions, videos)

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Related Topics: More Lessons for Chemistry Math Worksheets The number of protons in the nucleus of an atom is called the atomic number. It is represented by the symbol Z Example: Helium has an atomic number of 2 since it has two protons in its nucleus.

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Here is a fun way to test yourself with atomic mass/mass number calculations!

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Here is a fun way to test yourself with atomic mass/mass number calculations!

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Welcome to It's Elemental - Element Math Game! The computer will randomly pick an element and present you with that element's data from the Periodic Table of Elements. Use that information to answer the question that the computer asks about the number of protons, neutrons, electrons or nucleons (particles in the nucleus) that an atom of that element contains. Press the 'Check my answer' button after you have entered your answer.

If you don't know how to calculate the number of protons, neutrons, electrons or nucleons that are in an atom of an element, reading this page may help you.

Would you like to practice only the first 36 elements? Would you like the challenge of having questions with just big atomic numbers? If so, press the 'More options, please!' button and you will be able to select whichever elements you desire!

A JavaScript enabled web browser is required.

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How many protons are in an atom of an element? How many neutrons? How many electrons? Use this game to practice the calculations!

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Guided Practice on Filling Out Isotope Tables

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Guided Practice on Filling Out Isotope Tables

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Click on the link below to quiz yourself on isotope problems!

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Click on the link below to quiz yourself on isotope problems!

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If you’re seeing this message, it means we’re having trouble loading external resources on our website.

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Isotopes and Atomic Mass Computer Simulation 

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Isotopes and Atomic Mass Computer Simulation 

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This is the simulation used in class, so feel free to practice with it on your own as well!

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Founded in 2002 by Nobel Laureate Carl Wieman, the PhET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations. PhET sims are based on extensive education research and engage students through an intuitive, game-like environment where students learn through exploration and discovery.

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Video on How to Calculate Average Atomic Mass 

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Video on How to Calculate Average Atomic Mass 

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How to Calculate Atomic Mass Practice Problems

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To see all my Chemistry videos, check out http://socratic.org/chemistry How do you calculate atomic mass? You have to multiply the atomic weight of an atom (in amu, or atomic mass units) by the percent abundance expressed as a decimal. Then you add these together for all the isotopes of an atom.

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Video on How to Calculate Percent Abundance

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Video on How to Calculate Percent Abundance

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Atomic Mass: How to Calculate Isotope Abundance

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Average Atomic Mass and Percent Abundance Practice Problems

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Average Atomic Mass and Percent Abundance Practice Problems

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The problems are on the first page, with solutions on the second page.

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Video on the Overview of the Periodic Table

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Video on the Overview of the Periodic Table

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The Periodic Table: Crash Course Chemistry #4

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Click through this website to learn about the different groups of the periodic table!

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Click through this website to learn about the different groups of the periodic table!

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Interactives . The Periodic Table . Groups

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Teacher resources and professional development across the curriculum

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Information about Metals, Nonmetals, and Metalloids

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Information about Metals, Nonmetals, and Metalloids

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The elements of the periodic table can be broken into three different groups: Metals, Metalloids, and Nonmetals.

This periodic table shows the three different groups of elements. The metalloid group separates the metals from the nonmetals. Elements to the left are metals and nonmetals are to the right. The exception is the element hydrogen. Hydrogen has properties of a nonmetal at normal temperatures and pressures and an alkali metal under extremely high pressure.

Some periodic tables include a zig-zag line to distinguish between metals and metalloids. The line begins below boron (B) and extends between bismuth (Bi) and polonium (Po) or down between livermorium (Lv) and Tennessine (Ts). In reality, the metals near the line often display nonmetallic properties the nonmetals have some metallic character.
Properties of Metals
Most of the elements are metals. Metals include the alkali metal, alkaline earth, transition metal, basic metal, lanthanide, and actinide groups. Metals display the following properties:

Solid at room temperature (with the exception of mercury)

Usually shiny, with metallic luster

High melting point

Good conductor of heat

Good conductor of electricity

Malleable - able to be pounded into sheets

Ductile - can be pulled into wire

High density (exceptions: lithium, potassium and sodium)

Corrode in air or seawater

Lose electrons in reactions

Properties of Metalloids or Semimetals
Metalloids or semimetals possess some properties of metals and some of nonmetals. Metalloids typically have several forms or allotropes with very different properties. Characteristics of metalloids include:

Could be dull or shiny

Conduct heat and electricity, but not as well as metals

Good semiconductors

Usually malleable

Usually ductile

Can both gain and lose electrons in reactions

Properties of Nonmetals
The nonmetals include the nonmetals element group, plus the halogens, and noble gases. Properties of nonmetals include:

Dull, not shiny

Poor conductor of heat

Poor conductor of electricity

Not malleable or ductile, usually brittle

Lower density (when compared to metals)

Lower melting point and boiling points (when compared to metals)

Gain electrons in reactions

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Metals, Metalloids, and Nonmetals - Element Classification Groups

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The elements of the periodic table can be broken into three different groups: Metals, Metalloids, and Nonmetals. This periodic table shows the three different groups of elements. The metalloid group separates the metals from the nonmetals. Elements to the left are metals and nonmetals are to the right.

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How to Create a Smore for the Family and Group Properties Project

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How to Create a Smore for the Family and Group Properties Project

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Guidelines on Naming Molecular Compounds

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Guidelines on Naming Molecular Compounds

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Molecular compounds or covalent compounds are those in which the elements share electrons via covalent bonds. The only type of molecular compound a chemistry student is expected to be able to name is a binary covalent compound. This is a covalent compound made up of only two different elements.

Identifying Molecular Compounds

Molecular compounds contain two or more nonmetals (not the ammonium ion). Usually, you can recognize a molecular compound because the first element in the compound name is a nonmetal.

Some molecular compounds contain hydrogen, however, if you see a compound which starts with "H", you can assume it is an acid and not a molecular compound. Compounds consisting only of carbon with hydrogen are called hydrocarbons. Hydrocarbons have their own special nomenclature, so they are treated differently from other molecular compounds.

Writing Formulas for Covalent Compounds

Certain rules apply to the way names of covalent compounds are written:

The more electropositive element (further left on the periodic table) is listed before the more electronegative element (further right on the periodic table).

The second element is given an -ide ending.

Prefixes are used to denote how many atoms of each element are present in the compound.

Prefixes and Molecular Compound Names

Nonmetals may combine in a variety of ratios, so it is important that the name of a molecular compound indicates how many atoms of each type of element are present in the compound.

This is accomplished using prefixes. If there is only one atom of the first element, no prefix is used. It is customary to prefix the name of one atom of the second element with mono-. For example, CO is named carbon monoxide rather than carbon oxide.

Examples of Covalent Compound Names

SO ₂ - sulfur dioxide
SF ₆ - sulfur hexafluoride
CCl ₄ - carbon tetrachloride
NI ₃ - nitrogen triiodide

Writing the Formula from the Name

You can write the formula for a covalent compound from its name by writing the symbols for the first and second element and translating the prefixes into subscripts. For example, xenon hexafluoride would be written XF ₆. It is common for students to have trouble writing formulae from compounds names as ionic compounds and covalent compounds are often confused. You aren't balancing charges of covalent compounds; if the compound does not contain a metal, don't try to balance this!
Molecular Compound Prefixes

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How to Name Molecular or Covalent Compounds

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Molecular compounds or covalent compounds are those in which the elements share electrons via covalent bonds. The only type of molecular compound a chemistry student is expected to be able to name is a binary covalent compound. This is a covalent compound made up of only two different elements.

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Cations and anions are both ions. The difference between a cation and an anion is the net electrical charge of the ion.

Ions are atoms or molecules which have gained or lost one or more valence electrons giving the ion a net positive or negative charge. If the chemical species has more protons than electrons, it carries a net positive charge. If there are more electrons than protons, the species has a negative charge.

The number of neutrons determines the isotope of an element, but does not affect the electrical charge.

Cation Versus Anion

Cations are ions with a net positive charge.

Cation Examples: Silver: Ag⁺, hydronium: H ₃O⁺, and ammonium: NH ₄⁺

Anions are ions with a net negative charge.

Anion Examples: hydroxide anion: OH⁻, oxide anion: O ²⁻, and sulfate anion: SO ₄ ²⁻

Because they have opposite electrical charges, cations and anions are attracted to each other. Cations repel other cations, while anions repel other anions.

Predicting Cations and Anions

Sometimes you can predict whether an atom will form a cation or an anion based on its position on the periodic table. Alkali metals and alkaline earths always form cations. Halogens always form anions. Most other nonmetals typically form anions (e.g., oxygen, nitrogen, sulfur), while most metals form cations (e.g., iron, gold, mercury).

Writing Chemical Formulas

When writing the formula of a compound, the cation is listed before the anion.

For example, in NaCl, the sodium atom acts as the cation, while the chlorine atom acts as the anion.

When writing cation or anion symbols, the element symbol(s) is listed first. The charge is written as a superscript following the chemical formula.

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Understand the Difference Between a Cation and an Anion

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Cations and anions are both ions. The difference between a cation and an anion is the net electrical charge of the ion. Ions are atoms or molecules which have gained or lost one or more valence electrons giving the ion a net positive or negative charge.

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Naming Ionic Compounds with Transition Metals Introduction

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Practice determining ion charges from the Periodic Table based on numbers of subatomic particles - this was also used in class!

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Build an atom out of protons, neutrons, and electrons, and see how the element, charge, and mass change. Then play a game to test your ideas!

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List of Polyatomic Ions and Their Charges

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List of Polyatomic Ions and Their Charges

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Quizlet Sets for Practicing Naming Ionic Compounds with Roman Numerals

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Quizlet Sets for Practicing Naming Ionic Compounds with Roman Numerals

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roman numerals naming ionic compounds Flashcards and Study Sets | Quizlet

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Learn roman numerals naming ionic compounds with free interactive flashcards. Choose from 500 different sets of roman numerals naming ionic compounds flashcards on Quizlet.

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Practice naming molecular and ionic compounds with this quiz!

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This online quiz is intended to give you extra practice in naming compounds, writing formulas and calculating molar masses (formula weights).

Select your preferences below and click 'Start' to give it a try!

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This online quiz is intended to give you extra practice in naming compounds, writing formulas and calculating molar masses (formula weights). Select your preferences below and click 'Start' to give it a try!