Name: weak acid equilibrium in water
Uploaded: 2020-09-24T15:06:51.000Z
Duration: 4 min 2 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Chemistry

Matter and its Interactions

PS.Chm.6.3

Weak Acid Solutions

חומצה חלשה כמו מימן ציאניד היא חומצת ברונסטד מכיוון שהיא תורמת פרוטון למולקולת המים ויוצרת יון הידרוניום. חומצה חלשה מתפרקת חלקית במים לפי קבוע פירוק החומצה שלה, Ka, שהוא 4.9 כפול 10 בחזקת מינוס 10 למימן ציאניד. במימן ציאניד, ה-Ka שווה לריכוז ההידרוניום כפול ריכוז יוני הציאניד חלקי ריכוז מימן ציאניד.ניתן להשתמש בקבוע פירוק החומצה, Ka, כדי לחשב את ריכוז יוני ההידרוניום בתמיסת חומצה חלשה, ולפיכך את ה-pH של התמיסה. ריכוז יוני ההידרוניום וה-pH של תמיסת מימן ציאניד 0.15 מולר ניתנים לחישוב בעזרת ביטוי שיווי המשקל וטבלת ICE. ריכוזי חומצת מימן ציאנידי, הידרוניום וציאניד התחלתי ובשיווי משקל ניתנים לביטוי בטבלה שמראה את הריכוז ההתחלתי, את השינוי ואת ריכוזי שיווי המשקל של כל אחת מהמולקולות.כדי להגיע לשיווי משקל, הריכוז ההתחלתי של המגיבים פוחת בעוד הריכוז ההתחלתי של התוצרים גדל בהתאם ליחסי המולים שלהם. השינוי בריכוז של המגיבים והתוצרים מסומן כ-x. הצבת ריכוזי שיווי משקל במשוואה ב-Ka תניב x כפול x חלקי 0.15 מינוס x.בחומצות חלשות רבות, x, כמות הפירוק תהיה קטנה מאוד בהשוואה לריכוז ההתחלתי של 0.15 מול. 0.15 פחות x הוא 0.15 בקירוב. כשהמשוואה נפתרת, x שווה 8.6 כפול 10 בחזקת מינוס 6 מולר.הקירוב כי, 0.15 פחות x שווה 0.15, תקף רק אם x הוא פחות מ-5%של 0.15 מולים. כאן x הוא 0.0057%של 0.15 מול, ולכן הקירוב הזה תקף. לפיעך הריכוז של הידרוניום הוא 8.6 כפול 10 בחזקת מינוס 6 מולר.כדי לקבוע את ה-pH, מחשבים את הלוג השלילי של ריכוז יוני ההידרוניום. הפתרון מראה ש-pH של תמיסת מימן ציאניד 0.15 מולר הוא 5.07. ניתן להשתמש ב-pH של תמיסה לקביעת ה-Ka בחומצה חלשה.לדוגמה, חומצה אצטית מתפרקת חלקית ליוני הידרוניום וליוני אצטט כאשר היא מומסת במים. ה-Ka של חומצה אצטית ניתן לביטוי כריכוז יוני הידרוניום כפול ריכוז יוני אצטט חלקי ריכוז החומצה האצטית. אם ה-pH של 0.20 מולר תמיסת חומצה אצטית היא 2.72, ניתן לחשב את ריכוז ההידרוניום שלה שהוא 1.9 כפול 10 בחזקת מינוס 3 מולר.ניתן לבנות את טבלת ה-ICE מריכוזי שיווי המשקל ההתחלתי והריכוז ההתחלתי של החומצה האצטית, יוני ההידרוניום ויוני האצטט. בשימוש בספרות הערך, 0.20 פחות 1.9 כפול 10 בחזקת מינוס 3 שווה בעיקרון ל-0.20. על ידי הצבה של ערכי שיווי המשקל בנוסחת ה-Ka, נמצא כי Ka שווה 1.8 כפול 10 בחזקת מינוס 5.

תמיסת חומצה חלשה

<div style="direction:rtl">

מעט תרכובות פועלות כחומצות חזקות. מספר גדול בהרבה של תרכובות מתנהגות כחומצות חלשות ומגיבות רק באופן חלקי עם מים, מותירות רוב גדול של מולקולות מומסות בצורתן המקורית ומייצרות כמות קטנה יחסית של יוני הידרוניום. חומצות חלשות נפוצות בטבע, בהיותן החומרים האחראים בחלקם לטעם החריף של פירות הדר, לתחושת הצריבה של עקיצות חרקים ולריחות הלא נעימים הקשורים לריח הגוף. דוגמה מוכרת לחומצה חלשה היא חומצה אצטית, המרכיב העיקרי בחומץ: 
<img alt="Eq1" src="/files/ftp_upload/11400/11400_Equation_1.png" style="height: 50px;"> 

השימוש בחץ כפול במשוואה לעיל מציין את היבט התגובה החלקי של תהליך זה. בהמסה במים בתנאים אופייניים, רק כ-1% ממולקולות של חומצה אצטית קיימות בצורה מיוננת,CH3COO−. 

חישוב ריכוזי הידרוניום יוני וה-pH של תמיסת חומצה חלשה 

חומצה פורמית, HCO2H, היא חומר גירוי אחד הגורם לגוף להגיב לעקיצות ונשיכות מנמלים. מהו הריכוז של יון הידרוניום וה-pH של תמיסה של 0.534-M של חומצה פורמית? 
<img alt="Eq2" src="/files/ftp_upload/11400/11400_Equation_2.png" style="height: 50px;"> 

טבלת ICE עבור מערכת זו היא 
<table style="margin-left: auto; margin-right: auto;"> 
	<tbody> 

		<tr> 

			<td style="color: black; border: 1px solid black; text-align: center;"></td> 
			<td style="color: black; border: 1px solid black; text-align: center;">HCO2H (aq) </td> 
			<td style="color: black; border: 1px solid black; text-align: center;">H3O+ (aq)</td><td style="color: black; border: 1px solid black; text-align: center;">HCO2− (aq)</td> 
		</tr> 
		<tr> 

			<td style="color: black; border: 1px solid black; text-align: center;">ריכוז התחלתי (M)</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">0.534</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">~0</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">0</td> 
		</tr> 
		<tr> 

			<td style="color: black; border: 1px solid black; text-align: center;">שנה (M)</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">−x</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">+x</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">+x</td> 
		</tr> 
		<tr> 

			<td style="color: black; border: 1px solid black; text-align: center;">ריכוז שיווי משקל (M)</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">0.534 − x</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">x</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">x</td> 
		</tr> 
	</tbody> 
 </table> 

החלפת מונחי ריכוז שיווי המשקל בביטוי Ka נותן: 
<img alt="Eq3" src="/files/ftp_upload/11400/11400_Equation_3.png" style="height: 90px;"> 

הריכוז הראשוני הגדול יחסית וקבוע שיווי המשקל הקטן מאפשרים את ההנחה המפשטת ש-x יהיה הרבה פחות מ-0.534, ולכן המשוואה הופכת להיות: 
<img alt="Eq4" src="/files/ftp_upload/11400/11400_Equation_4.png" style="height: 90px;"> 

פתרון המשוואה ל-x מניב: 
<img alt="Eq5" src="/files/ftp_upload/11400/11400_Equation_5.png" style="height: 90px;"> 

כדי לבדוק את ההנחה ש-x קטן בהשוואה ל-0.534, ניתן להעריך את גודלו היחסי: 
<img alt="Eq6" src="/files/ftp_upload/11400/11400_Equation_6.png" style="height: 90px;"> 

מכיוון ש-x הוא פחות מ-5% מהריכוז ההתחלתי, ההנחה תקפה. כפי שהוגדר בטבלת ICE, x שווה לריכוז שיווי המשקל של יון הידרוניום: 
<img alt="Eq7" src="/files/ftp_upload/11400/11400_Equation_7.png" style="height: 50px;"> 

לבסוף, ה-pH מחושב להיות 
<img alt="Eq8" src="/files/ftp_upload/11400/11400_Equation_8.png" style="height: 50px;"> 

קביעת Ka מ-pH 

ה-pH של תמיסה של 0.0516 M של חומצה חנקתית, HNO2, הוא 2.34. מה הוא ה-Kaשלה? 
<img alt="Eq9" src="/files/ftp_upload/11400/11400_Equation_9.png" style="height: 50px;"> 

ריכוז החומצה החנקנית המסופק הוא ריכוז פורמלי, כזה שאינו אחראי על שיווי משקל כימי כלשהו שעלול להתבסס בתמיסה. ריכוזים כאלה מטופלים כערכים "ראשוניים" עבור חישובי שיווי משקל באמצעות גישה לטבלת ICE. שימו לב שהערך ההתחלתי של יון הידרוניום רשום כאפס בערך מכיוון שקיים ריכוז קטן של H3O+ (1 × 10−7 M) עקב יינון אוטומטי של מים. במקרים רבים, ריכוז זה נמוך בהרבה מזה שנוצר על ידי יינון של החומצה (או הבסיס) המדובר, ועלול להיות מוזנח. 

ה-pH המסופק הוא מדד לוגריתמי של ריכוז יוני ההידרוניום הנובע מיינון החומצה של החומצה החנקנית, ולכן הוא מייצג ערך "שיווי משקל" לטבלת ICE: 
<img alt="Eq1" src="/files/ftp_upload/11400/11400_Equation_10.png" style="height: 50px;"> 

טבלת ICE עבור מערכת זו היא: 
<table style="margin-left: auto; margin-right: auto;"> 
	<tbody> 
		<tr> 

			<td style="color: black; border: 1px solid black; text-align: center;"></td> 
			<td style="color: black; border: 1px solid black; text-align: center;">HNO2 (aq) </td> 
			<td style="color: black; border: 1px solid black; text-align: center;">H3O+ (aq)</td><td style="color: black; border: 1px solid black; text-align: center;">NO2− (aq)</td> 
		</tr> 
		<tr> 

			<td style="color: black; border: 1px solid black; text-align: center;">ריכוז התחלתי (M)</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">0.0516</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">~0</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">0</td> 
		</tr> 
		<tr> 

			<td style="color: black; border: 1px solid black; text-align: center;">שינוי (M)</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">−0.0046</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">+0.0046</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">+0.0046</td> 
		</tr> 
		<tr> 

			<td style="color: black; border: 1px solid black; text-align: center;">ריכוז שיווי משקל (M)</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">0.0470</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">0.0046</td> 
			<td style="color: black; border: 1px solid black; text-align: center;">0.0046</td> 
		</tr> 
	</tbody> 
 </table> 

לבסוף, חשב את הערך של קבוע שיווי המשקל באמצעות הנתונים בטבלה: 
<img alt="Eq11" src="/files/ftp_upload/11400/11400_Equation_11.png" style="height: 90px;"> 

טקסט זה מותאם מ<a href="https://openstax.org/books/chemistry-2e/pages/4-2-classifying-chemical-reactions">Openstax, Chemistry 2e, Section 4.2: Classifying Chemical Reactions</a> and <a href="https://openstax.org/books/chemistry-2e/pages/14-3-relative-strengths-of-acids-and-bases">Openstax, Chemistry 2e,14.3 Relative Strengths of Acids and Bases.</a>

</div>

תרכובות מעטות פועלות כחומצות חזקות. מספר גדול בהרבה של תרכובות מתנהגות כחומצות חלשות ומגיבות רק באופן חלקי עם מים, מה שמשאיר את הרוב הגדול של ...

Education

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כימיה

אחד

Acids and Bases

חומצות ובסיסים

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

weak acid equilibrium in water

Weak acid equilibrium in water explains why many acids only partially react when dissolved. Most weak acid molecules stay in their original form, and only a small amount of hydronium ions forms. Weak acids are common in nature. They help create the tangy taste of citrus fruits, the stinging sensation from insect bites, and the smells linked to body odor.

Acetic acid is a familiar weak acid. It is the main ingredient in vinegar. Its equation uses a double arrow to show that the reaction with water is only partial. Under typical conditions, only about 1% of acetic acid molecules are present as the ionized form, CH3COO−.

Weak acid problems often use an ICE table to find hydronium ion concentration and pH. Formic acid, HCO2H, is one example because it can cause the irritation from some ant bites and stings. For a 0.534-M formic acid solution, the ICE table starts with formic acid, H3O+, and HCO2−, then tracks the change as x forms and the equilibrium amounts are written in terms of x. The Ka expression is set up from those equilibrium concentrations.

Because the initial formic acid concentration is much larger than the amount that reacts, x is assumed to be much less than 0.534. That lets the expression simplify and makes the calculation easier. After solving for x, the result is checked against the 5% rule. Since x is less than 5% of the initial concentration, the assumption is valid. The value of x equals the equilibrium hydronium ion concentration, and the pH is then calculated from that concentration.

The same ICE table method can also be used in reverse to find Ka from pH. For nitrous acid, HNO2, the given pH is 2.34 for a 0.0516-M solution. That concentration is a formal concentration, which means it does not include any equilibrium changes. In these setups, the initial hydronium ion is shown as approximately zero because water already contains a very small amount, about 1 × 10−7 M, from autoionization. In many cases, that amount is much smaller than the acid-produced hydronium ion and can be ignored.

The pH gives the equilibrium hydronium ion concentration for the nitrous acid solution. The ICE table then shows HNO2, H3O+, and NO2− changing to equilibrium values. Using those values in the equilibrium expression gives the Ka of the acid. This approach shows how pH and Ka connect to the behavior of weak acids in water.

Weak Acid Equilibrium in Water

bronsted-lowry acids and bases

Proton Transfer in Acids and Bases

Acids and bases can be understood through proton transfer. Early scientists described acids by their sour taste, their effect on dyes, and their reaction with limestone, which releases carbon dioxide. Robert Boyle also noted that acid solutions can lose these properties after contact with alkali, or base, solutions. The modern view developed step by step. Humphry Davy showed that hydrogen is the essential part of acids. Joseph Louis Gay-Lussac then described acids as substances that neutralize...

water: a bronsted-lowry acid and base

Water as an Amphiprotic Substance

Water can act as both a Brønsted-Lowry acid and a Brønsted-Lowry base. When hydrogen fluoride dissolves in water, it donates protons to water. This is acid ionization. The products are hydronium ions and fluoride ions. Water can also accept protons from another substance. When pyridine dissolves in water, it accepts a proton from water molecules. This is base ionization. The products are hydroxide ions and pyridinium ions. These reactions show that water can play either role. A substance that...

ph scale

pH and pOH in Water

pH and pOH show how hydronium and hydroxide ions behave in water and other aqueous solutions. These ion concentrations are linked by the ion product of water, K w , so when one goes up, the other goes down. Because ion concentrations can differ by huge amounts, a logarithmic scale is used to describe them. pH is defined from the hydronium ion concentration, [H3O+], and pOH is the matching p-function for hydroxide ion concentration. These two values are also connected through the K w...

relative strengths of conjugate acid-base pairs

relative-strengths-of-conjugate-acid-base-pairs

How Ka and Kb Show Acid-Base Strength

Brønsted-Lowry acid-base chemistry is based on proton transfer. That idea helps show how the strength of an acid is linked to the strength of its conjugate base, and vice versa. Acid and base strength is measured with ionization constants, Ka and Kb, which tell how far an ionization reaction goes. For the conjugate pair HA and A−, the acid ionizes in water and the base reaction can be written for the partner species. When the two reactions are added, they give the autoionization of water. The...

strong acid and base solutions

Strong Acids, Strong Bases, and pH

Strong acids and strong bases change the pH of a solution by dissociating completely in water. A strong acid produces hydronium ions, which are H3O+ ions, and a strong base produces hydroxide ions, OH-. Because the dissociation is complete, the ion concentration can be found from the starting concentration and the molar ratio. For example, 0.20 M hydrobromic acid dissociates fully in water. It produces 0.20 M hydronium ions and 0.20 M bromide ions. A 0.015 M KOH solution also dissociates...

weak acid solutions

Weak acid equilibrium in water explains why many acids only partially react when dissolved. Most weak acid molecules stay in their original form, and only a small amount of hydronium ions forms. Weak acids are common in nature. They help create the tangy taste of citrus fruits, the stinging sensation from insect bites, and the smells linked to body odor. Acetic acid is a familiar weak acid. It is the main ingredient in vinegar. Its equation uses a double arrow to show that the reaction with...

weak base solutions

Weak Base pH and Kb Calculations

Weak base pH and Kb calculations show how partially reacting bases change water chemistry. Weak bases produce hydroxide ions when they dissolve by reacting with water molecules. Because the reaction only happens partly, these compounds are classified as weak bases. Weak bases are common in nature and in technology. Ammonia is one major example. Global production of ammonia is typically well over 100 metric tons each year. It is used as an agricultural fertilizer, a starting material for...

mixtures of acids

pH of Acid Mixtures

The pH of acid mixtures depends on the acids present, their dissociation constants, and their starting concentrations. When a solution contains two different acids, the pH can be found by choosing the method that fits their relative strengths. This makes acid mixtures a useful case for applying acid-base rules in chemistry. In a mixture of a strong acid and a weak acid, the strong acid dissociates completely and supplies almost all of the hydronium ions in the solution. The weak acid...

ions as acids and bases

Salt Hydrolysis and pH of Solutions

Salt hydrolysis explains why some salt solutions are acidic, basic, or neutral. Salts are ionic compounds made of cations and anions. In water, either ion may react with water through an acid or base ionization reaction. The pH of the solution depends on the relative acid-base strength of the ions in the salt. Ammonium chloride is a good example of an acidic salt. When it dissolves, it separates into ammonium ions and chloride ions. The ammonium ion is the conjugate acid of ammonia, so it can...

determining the ph of salt solutions

Salt Hydrolysis and pH in Solutions

Salt hydrolysis and pH in solutions depend on the ions released when a salt dissolves. Some ions react with water, while others do not. The balance between the cation and anion helps show whether the solution becomes acidic, basic, or neutral. Salts with pH-neutral anions and cations that produce hydronium ions give acidic solutions with pH below 7. Ammonium nitrate is one example. In NH4NO3, NO3− does not react with water, but NH4+ forms hydronium ions, so the solution is acidic. Other salts...

acid/base strengths and dissociation constants

acidbase-strengths-and-dissociation-constants

Acid and Base Strength in Water

Acid and base strength in water depends on how much a substance ionizes after it dissolves. If ionization is nearly complete, the substance is called strong. If only a small amount ionizes, it is called weak. Weak acids and weak bases are much more common than strong ones. The most common strong acids are HClO4, HCl, HBr, HI, HNO3, and H2SO4. The most common strong bases are LiOH, NaOH, KOH, Ca(OH)2, Sr(OH)2, and Ba(OH)2. These strong acids and bases ionize essentially completely in water. <br...

polyprotic acids

Stepwise Ionization of Polyprotic Acids

Polyprotic acids lose hydrogen ions in steps. The number of ionizable protons in a molecule determines whether an acid is monoprotic, diprotic, or triprotic. This video also shows that polyprotic bases can accept more than one proton. Monoprotic acids have one ionizable hydrogen atom per molecule. Examples include HCl, HNO3, and HCN. Their reactions with water form hydronium ions and the matching anion. Acetic acid, CH3CO2H, is also monoprotic because only the hydrogen in the carboxyl group...

acid strength and molecular structure

How Bonding Affects Acid Strength

Acid strength depends on bonding, electronegativity, and oxidation number. These factors help explain why some hydrogen compounds act as strong acids, while others behave as weak acids or bases. For binary acids, which are hydrogen compounds with one other nonmetal, acidity increases as the H-A bond gets weaker down a group. That is why the order for group 17 is HF &lt; HCl &lt; HBr &lt; HI, and for group 16 it is H2O &lt; H2S &lt; H2Se &lt; H2Te. Across a period, acid strength increases as...

lewis acids and bases

Electron-Pair Reactions in Acid-Base Chemistry

Electron-pair reactions explain Lewis acid-base chemistry. In 1923, G. N. Lewis described acids and bases by how they accept or donate a pair of electrons. When that electron pair forms a coordinate covalent bond, one atom supplies both bonding electrons. This bond is also called a dative bond. A simple example is the reaction of water with a hydrogen ion to make a hydronium ion. Ammonia can also combine with a hydrogen ion to form an ammonium ion. In both cases, the reaction creates a Lewis...

key terms and concepts

Explore how weak acids partially ionize in water, use ICE tables to find hydronium ion concentration and pH, and calculate Ka from pH.

Weak Acid Equilibrium in Water | JoVE K12

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Physical Science

PS.PSc.2.5

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Interactions Of Matter

Chemical reactions

Minnesota Academic Standards in Science

1.2.1 9L.4.2.2.1

Texas Essential Knowledge and Skills

High School

CHEM.12

CHEM.12.C

Alabama Course of Study Science

Matter and Its Interactions

9-12.C.1.6.a

9-12.PS.3.6.c

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Chemical Reactions

HS-PS1-11.

Scientific Laws and Theories

Scientific Laws

In science, a law is defined as a concise, verbal or mathematical, statement that summarizes a vast number of experimental observations. ...

The Scientific Method

Chemistry is an empirical science. Scientists often pose questions to understand the chemistry in everyday life and seek answers to these questions. To ...

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 ...

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 ...

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 ...

Use models to explain how the scientific understanding of atomic structure has evolved.

PS.Chm.1.1

Radioactivity and Nuclear Equations

Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for ...

Types of Radioactivity

The most common types of radioactivity are &#945; decay, &#946; decay, &#947; decay, neutron emission, and electron capture.
Alpha (&#945;) decay is the ...

Nuclear Stability

Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10&#8722;15 meters, a nucleus is ...

Nuclear Binding Energy

The difference between the calculated and experimentally measured masses is known as the mass defect of the atom. In the case of helium-4, the mass defect ...

Radioactive Decay and Radiometric Dating

Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. ...

Nuclear Fission

Many heavier elements with smaller binding energies per nucleon can decompose into more stable elements that have intermediate mass numbers and larger ...

Nuclear Power

Controlled nuclear fission reactions are used to generate electricity. Any nuclear reactor that produces power via the fission of uranium or plutonium by ...

Nuclear Fusion

The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process ...

Nuclear Transmutation

Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with ...

Use models to compare nuclear reactions including alpha decay, beta decay and gamma decay; nuclear fusion and nuclear fission.

PS.Chm.1.2

Atomic Orbitals

An atomic orbital represents the three-dimensional regions in an atom where an electron has the highest probability to reside. The radial distribution ...

The Pauli Exclusion Principle

The arrangement of electrons in the orbitals of an atom is called its electron configuration. We describe an electron configuration with a symbol that ...

The Energies of Atomic Orbitals

In an atom, the negatively charged electrons are attracted to the positively charged nucleus. In a multielectron atom, electron-electron repulsions are ...

The Aufbau Principle and Hund's Rule

To determine the electron configuration for any particular atom, we can build the structures in the order of atomic numbers. Beginning with hydrogen, and ...

electron-configuration-of-multielectron-atoms

Electron Configuration of Multielectron Atoms

The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the ...

Use models to explain how electrons are distributed in atoms.

PS.Chm.1.3

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 ...

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 ...

Atomic Mass

Atoms &mdash; and the protons, neutrons, and electrons that compose them &mdash; are extremely small. For example, a carbon atom weighs less than 2 ...

Molar Mass

The identity of a substance is defined not only by the types of atoms or ions it contains but by the quantity of each type of atom or ion. For example, ...

Use the Periodic Table as a model to predict the relative properties of elements based on the pattern of valence electrons in the outermost energy levels of atoms.

PS.Chm.2.1

atomic-radii-and-effective-nuclear-charge

Atomic Radii and Effective Nuclear Charge

The elements in groups of the periodic table exhibit similar chemical behavior. This similarity occurs because the members of a group have the same number ...

Ionic Radii

Ionic radius is the measure used to describe the size of an ion. A cation always has fewer electrons and the same number of protons as the parent atom; it ...

Ionization Energy

The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state is called its first ionization energy ...

Electron Affinity

The electron affinity (EA) is the energy change for adding an electron to a gaseous atom to form an anion (negative ion).



This process can be either ...

Construct an explanation to infer the atomic size, reactivity, electronegativity, and ionization energy of an element based on its position in the Periodic Table.

PS.Chm.2.2

Types of Chemical Bonds

Chemical bonding theories were pioneered by American chemist Gilbert&#xA0;N. Lewis. He developed a model called the Lewis model to explain the type and ...

Lewis Symbols and the Octet Rule

Chemical bonds are complex interactions between two or more atoms or ions, which reduce the potential energy of the molecule. Gilbert N. Lewis developed a ...

Ionic Bonding and Electron Transfer

Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence ...

The Born-Haber Cycle

Lattice Energy&#xA0;

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a ...

trends-in-lattice-energy-ion-size-and-charge

Trends in Lattice Energy: Ion Size and Charge

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure ...

Covalent Bonding and Lewis Structures

Compared to ionic bonds, which results from the transfer of electrons between metallic and nonmetallic atoms, covalent bonds result from the mutual ...

Electronegativity

Whether a bond is nonpolar or polar covalent is determined by a property of the bonding atoms called electronegativity.&#xA0;

Electronegativity values of ...

bond-polarity-dipole-moment-and-percent-ionic-character

Bond Polarity, Dipole Moment, and Percent Ionic Character

Bond Polarity

The absolute value of the difference in electronegativity (&Delta;EN) of two bonded atoms provides a rough measure of the polarity to be ...

lewis-structures-of-molecular-compounds-and-polyatomic-ions

Lewis Structures of Molecular Compounds and Polyatomic Ions

To draw Lewis structures for complicated molecules and molecular ions, it is helpful to follow a step-by-step procedure as outlined:


	Determine the ...

Resonance

The Lewis structure of a nitrite anion (NO2&minus;) may actually be drawn in two different ways, distinguished by the locations of the N-O and N=O ...

Formal Charges

In some cases, there are seemingly more than one valid Lewis structures for molecules and polyatomic ions. The concept of formal charges can be used to ...

Exceptions to the Octet Rule

Many covalent molecules have central atoms that do not have eight electrons in their Lewis structures. These molecules fall into three categories:


	...

Bond Energies and Bond Lengths

Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, ...

Analyze and interpret data to explain the mechanisms and properties of the two main types of intramolecular (ionic and covalent) bonds.

PS.Chm.3.1

molecular-comparison-of-gases-liquids-and-solids

Molecular Comparison of Gases, Liquids, and Solids

Particles in a solid are tightly packed together (fixed shape) and often arranged in a regular pattern; in a liquid, they are close together with no ...

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 ...

comparing-intermolecular-forces-melting-point-boiling-point

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, ...

Construct an explanation to summarize the influences intermolecular forces have on the properties of chemical compounds.

PS.Chm.3.2

Analyze the structure of atoms and isotopes.

Weak Acid Equilibrium in Water

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