Name: matter: elements, compounds, and mixtures
Uploaded: 2020-09-03T13:38:25.000Z
Duration: 3 min 35 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

Energy

PS.Chm.7.1

Classifying Matter by Composition

חומר עשוי מאטומים, שהן היחידות הכי קטנות ובסיסיות של החומר, וממולקולות, אשר נוצרות על ידי חיבור של שני אטומים או יותר. לפי הרכבו, את החומר ניתן לסווג אותו לאחת משתי קבוצות:חומרים טהורים ותערובות. בהגדרה, נאמר על חומר שהוא טהור אם הוא מורכב רק מרכיב אחד עם הרכב אחיד בכולו.לדוגמה, מימן. מימן מורכב מאטומי מימן בלבד. בדומה לכך, מים מורכבים ממולקולות מים בלבד.ההרכבים הללו לא משתנים בין דוגמיות. חומרים טהורים ניתנים לסיווג לשני סוגים:יסודות ותרכובות, כתלות בהאם ניתן לפרק אותם. יסודות הם חומרים טהורים שלא ניתן לפרק לחומרים פשוטים יותר באמצעים כימיים.לדוגמה, מימן הוא יסוד. תרכובות, לעומת זאת, הן חומרים שניתן להפריד למרכיבים שלהן רק באמצעים כימיים. לדוגמה, מים, שגם הם חומר טהור, ניתן לפרק כימית לשני מרכיבים פשוטים יותר, מימן וחמצן.המשמעות היא שזו תרכובת. בכדור הארץ, תרכובות שכיחות יותר מיסודות טהורים מפני שרוב היסודות בקלות להיקשר עם יסודות אחרים. לדוגמה, גיר שמשתמשים בו לכתיבה על לוח מורכב מ:סידן, פחמן וחמצן.סוכר מורכב מ:פחמן, מימן וחמצן. תערובות, בשונה מחומרים טהורים, עשויות ממרכיב אחד או יותר. היחס בין המרכיבים שלהן יכול להשתנות בין דוגמיות.לדוגמה, לימונדה היא תערובות של שלושה מרכיבים:מיץ לימון, סוכר ומים, והיחס ביניהם יכול להשתנות כדי להפוך את המשקה למתוק יותר או פחות. ניתן לחלק תערובות לשני סוגים:הומוגניות והטרוגניות, תלוי עד כמה אחיד האופן בו החומרים בתוך התערובת מתערביים. לתערובת הומוגנית יש הרכב אחיד והמראה שלה הוא אחיד.לעיתים היא תיקרא תמיסה. לדוגמה, כף מלאה במלח מומס במים תיתן תערובות הומוגנית מפני שלכל טיפה בתערובת יש את אותו הרכב. בדומה לכך, גם לימונדה היא תערובת הומוגנית.בתערובות הטרוגניות, המרכיבים לא מפוזרים באופן אחיד, ולכן ההרכב משתנה בחלקים שונים. לדוגמה, בחול המעורבב בשבבי ברזל, כאן בחלקים שונים בתערובת כנראה תהיינה כמויות שונות של שבבי ברזל וחול. ללא קשר לכך, כל תערובת, בין אם היא הומוגנית או הטרוגנית יכולה להיות מופרדת לחומרים הטהורים המרכיבים אותה באמצעים פיזיקליים, מבלי לשנות את זהות המרכיבים.לדוגמה, ניתן להוציא מלח מתמיסת המים על ידי חימום התערובת עד שתתייבש. בדומה לכך, ניתן להפריד שבבי ברזל מחול בעזרת מגנט.

סיווג חומר לפי ההרכב

<div style="direction:rtl"><h4>חומר: חומרים ותערובות טהורים</h4> על פי הרכבו, ניתן לסווג את הנושא לשתי קטגוריות רחבות - חומרים טהורים ותערובות. חומר טהור הוא צורת חומר בעלת הרכב קבוע לכל אורכו עם תכונות אחידות. לדוגמה, לכל דגימה של סוכרוז יש את אותו הרכב ואותן תכונות פיזיקליות, כגון נקודת התכה, צבע ומתיקות, ללא קשר למקור ממנו היא מבודדת. תערובת מורכבת משני סוגים או יותר של חומר שיכולים להיות נוכחים בכמויות שונות וניתן להפריד אותם על ידי שינויים פיזיקליים, כגון אידוי. הרכיבים בתערובת שומרים על זהותם המובהקת. <h4>חומרים טהורים: יסודות ותרכובות</h4> ניתן לחלק חומרים טהורים לשתי מחלקות: יסודות ותרכובות. חומרים טהורים שלא ניתן לפרק לחומרים פשוטים יותר על ידי שינויים כימיים נקראים יסודות. ברזל, כסף, זהב, אלומיניום, גופרית, חמצן ונחושת הם יסודות. חומרים טהורים שניתן לפרק על ידי שינויים כימיים נקראים תרכובות. התמוטטות זו עשויה לייצר יסודות או תרכובות אחרות, או שניהם. תחמוצת כספית(II), מוצק קריסטלי כתום, יכול להתפרק על ידי חום ליסודות כספית וחמצן. בחימום בהיעדר אוויר, התרכובת סוכרוז מתפרקת ליסוד פחמן ולמים המורכבים. כסף(I) כלוריד הוא מוצק לבן שניתן לפרק ליסודות שלו, כסף וכלור, על ידי ספיגת אור. המאפיינים של יסודות משולבים שונים מאלה במצב חופשי או לא משולב. לדוגמה, סוכר קריסטלי לבן (סוכרוז) הוא תרכובת הנובעת מהשילוב הכימי של היסוד פחמן, שהוא מוצק שחור באחת מצורותיו הלא משולבות, ושני היסודות מימן וחמצן, שהם גזים חסרי צבע כאשר אינם משולבים. נתרן חופשי, יסוד שהוא מוצק רך, מבריק, מתכתי, וכלור חופשי, יסוד שהוא גז צהוב-ירוק, מתאחדים ויוצרים נתרן כלורי (מלח שולחן), תרכובת שהיא מוצק קריסטלי לבן. <h4>תערובות: הומוגניות והטרוגניות</h4> תערובת הומוגנית, הנקראת גם תמיסה, מציגה הרכב אחיד ונראית זהה מבחינה ויזואלית לאורך כל הדרך. דוגמה לתמיסה הוא משקה ספורט, המורכב ממים, סוכר, צבע, חומרי טעם וריח ואלקטרוליטים המעורבבים יחד באופן אחיד. לכל טיפה של משקה ספורט יש טעם זהה מכיוון שכל טיפה מכילה את אותן כמויות של מים, סוכר ורכיבים אחרים. שימו לב שההרכב של משקה ספורט יכול להשתנות - אפשר להכין אותו עם קצת יותר או פחות סוכר, חומרי טעם וריח או רכיבים אחרים, ועדיין להיות משקה ספורט. דוגמאות נוספות לתערובות הומוגניות כוללות אוויר, סירופ מייפל, בנזין ותמיסת מלח במים. תערובת בעלת הרכב משתנה מנקודה לנקודה נקראת תערובת הטרוגנית. רוטב איטלקי הוא דוגמה לתערובת הטרוגנית. הרכבו יכול להשתנות מכיוון שהוא עשוי להיות מוכן מכמויות שונות של שמן, חומץ ועשבי תיבול. זה לא זהה מנקודה לנקודה בכל התערובת - טיפה אחת עשויה להיות בעיקר חומץ, ואילו טיפה שונה עשויה להיות בעיקר שמן או עשבי תיבול כי השמן והחומץ נפרדים ועשבי התיבול מתיישבים. דוגמאות נוספות לתערובות הטרוגניות הן עוגיות שוקולד צ'יפס (נוכל לראות את החלקים הנפרדים של שוקולד, אגוזים ובצק עוגיות) וגרניט (נוכל לראות את הקוורץ, המיקה, השדה ספייר ועוד). כל תערובת, בין אם הומוגנית או הטרוגנית, ניתנת להפרדה לרכיבים טהורים באמצעים פיזיקליים מבלי לשנות את זהויות הרכיבים. למרות שיש קצת יותר מ-100 יסודות, עשרות מיליוני תרכובות כימיות נובעות משילובים שונים של יסודות אלו. לכל תרכובת יש הרכב מסוים ובעלת תכונות כימיות ופיזיקליות ברורות המבדילות אותה מכל שאר התרכובות. וכמובן, יש אינספור דרכים לשלב יסודות ותרכובות ליצירת תערובות שונות. טקסט זה מותאם מ <a href="https://openstax.org/books/chemistry-2e/pages/1-2-phases-and-classification-of-matter">Openstax, Chemistry 2e, Section 1.2: Phases and Classification of Matter. </a></div>

חומר: חומרים טהורים ותערובות
על פי הרכבו, ניתן לסווג את העניין לשתי קטגוריות רחבות - חומרים טהורים ו ...

Education

JoVE Core

כימיה

אחד

Introduction: Matter and Measurement

מבוא: חומר ומדידה

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

matter: elements, compounds, and mixtures

Matter can be grouped by composition into pure substances and mixtures. A pure substance has a constant composition throughout and uniform properties. For example, any sample of sucrose has the same composition and the same physical properties, such as melting point, color, and sweetness, no matter where it is isolated from.

A mixture contains two or more kinds of matter in varying amounts. Its parts can be separated by physical changes, such as evaporation. The components keep their own identities, so the mixture is not a new substance in the same way a compound is.

Pure substances are divided into elements and compounds. Elements cannot be broken down into simpler substances by chemical changes. Iron, silver, gold, aluminum, sulfur, oxygen, and copper are examples of elements.

Compounds are pure substances that can be broken down by chemical changes. This breakdown may produce elements, other compounds, or both. Mercury(II) oxide can be heated to form mercury and oxygen, sucrose can break down into carbon and water when heated without air, and silver(I) chloride can be broken down by light into silver and chlorine.

The properties of combined elements are different from the properties of the elements in their free state. White crystalline sugar comes from carbon, hydrogen, and oxygen, but those elements look very different when uncombined. Free sodium is a soft, shiny metal, and free chlorine is a yellow-green gas, yet together they form sodium chloride, a white crystalline solid.

Mixtures can be homogeneous or heterogeneous. A homogeneous mixture, also called a solution, has a uniform composition and looks the same throughout. Sports drink is one example. It contains water, sugar, coloring, flavoring, and electrolytes mixed evenly, so each drop tastes the same. Its exact composition can still vary and remain a sports drink. Air, maple syrup, gasoline, and salt water are other homogeneous mixtures.

A heterogeneous mixture has a composition that varies from point to point. Italian dressing is one example, since the amounts of oil, vinegar, and herbs can differ and the parts may separate or settle. Chocolate chip cookies and granite are also heterogeneous mixtures because their different parts can be seen.

Any mixture, whether homogeneous or heterogeneous, can be separated into pure components by physical means without changing what the components are. There are just over 100 elements, but they combine in many ways to form tens of millions of compounds. Each compound has a specific composition and its own chemical and physical properties. Elements, compounds, and mixtures can combine in countless ways to make matter.

Matter: Elements, Compounds, and Mixtures

scientific laws and theories

How Science Explains Laws and Theories

Scientific laws and scientific theories describe science in two different ways. A law is a concise verbal or mathematical statement that summarizes many experimental observations. It describes or predicts aspects of the natural world that stay the same under the same conditions. A scientific theory is different because it explains why natural events happen. It is a unifying principle that gives a well-supported and testable explanation for a broad set of observations. Strong theories are the...

the scientific method

How Scientists Test a Hypothesis

Chemistry uses the scientific method to turn observations into testable answers. Scientists begin by observing a phenomenon in the physical world and then asking a question about it. This process helps explain everyday chemistry through evidence. A question leads to a hypothesis, which is a tentative explanation for what is being observed. Scientists often use earlier research and published literature to shape that idea. A strong hypothesis must be testable, meaning it can be supported by...

physical and chemical properties of matter

physical-and-chemical-properties-of-matter

Distinguishing Physical and Chemical Changes

Matter can be identified by its properties, which are the features that help us tell one substance from another. These properties fall into two main groups: physical properties and chemical properties. Understanding the difference helps explain how matter changes. A physical property is a feature of matter that is not linked to a change in chemical composition. Examples include density, color, hardness, melting point, boiling point, and electrical conductivity. Some physical properties can be...

what is energy?

Energy Forms and Conservation

Energy is a property of matter that appears in many forms. On Earth, most energy starts with the Sun. Plants capture light energy from the Sun and use photosynthesis to turn it into chemical energy. That stored energy can then move through living things and materials in several ways. People get energy from plant foods, and wood or coal, which come from fossilized plants, can be burned to produce heat and electricity. Energy is defined as the ability to do work. Work happens when a force moves...

classifying matter by state

States of Matter and Their Properties

States of matter help describe how matter behaves in chemistry. Matter is anything that has mass and takes up space. It is found everywhere, including air, water, soil, mountains, and even our bodies. The three common states on Earth are solid, liquid, and gas. A solid has a definite shape and a definite volume. Its particles, such as atoms or molecules, are packed very closely together and held in place by strong forces, so they only vibrate slightly. This tight arrangement makes solids...

measurement: standard units

Measurement: SI Units and Conversions

Measurement gives three kinds of information: a number, a unit, and an estimate of uncertainty. The number shows size or magnitude. The unit gives a standard for comparison. The uncertainty reflects possible error in the measurement. Numbers can be written in more than one way. A value may appear in decimal form or in scientific notation, which is also called exponential notation. For example, the maximum take-off weight of a Boeing 777-200ER airliner is 298,000 kilograms, or 2.98 × 10^5 kg. <br...

classifying matter by composition

Matter can be grouped by composition into pure substances and mixtures. A pure substance has a constant composition throughout and uniform properties. For example, any sample of sucrose has the same composition and the same physical properties, such as melting point, color, and sweetness, no matter where it is isolated from. A mixture contains two or more kinds of matter in varying amounts. Its parts can be separated by physical changes, such as evaporation. The components keep their own...

measurement: derived units

SI Units, Density, and Property Types

SI units and derived units help describe physical properties in chemistry. The International System of Units, or SI system, uses agreed-upon base units for seven fundamental properties: length, mass, time, temperature, electric current, amount of substance, and luminosity. Units made by combining these base units are called SI-derived units. Speed is one example. If distance is measured in meters and time in seconds, the derived unit for speed is meters per second, or m/s. Miles per hour is...

dimensional analysis

Using Conversion Factors to Cancel Units

Dimensional analysis is a method for using conversion factors to cancel units and solve measurement problems. It is also called the factor label method. The main rule is that units must be treated the same way as the numbers attached to them. A conversion factor is a ratio of two equal quantities written in different units. For example, 1 meter is equal to 1.0936 yards. That relationship can be used to build a factor that converts one unit into the other. When a value is multiplied or divided...

uncertainty in measurement: accuracy and precision

uncertainty-in-measurement-accuracy-and-precision

Measurement Error: Reading Results Correctly

Measurement error affects how scientists judge the quality of their results. Repeated measurements help show whether results are precise and accurate. A measurement is precise when repeated values are very similar. A measurement is accurate when it is very close to the true or accepted value. Precise values agree with each other, while accurate values agree with the true value. A pharmaceutical quality control chemist can use this idea to check machines that dispense 500 mL of cough syrup. The...

uncertainty in measurement: reading instruments

uncertainty-in-measurement-reading-instruments

Measurement Uncertainty and Significant Figures

Measurement uncertainty and significant figures show how carefully a value can be read from an instrument. Counting is different. If the number of objects does not change during counting, the result is exact. Defined quantities are exact too. For example, 1 foot is exactly 12 inches, 1 inch is exactly 2.54 centimeters, and 1 gram is exactly 0.001 kilograms. Most other measurements are not exact because the measuring process has limits. The result depends on the device used and on the person...

uncertainty in measurement: significant figures

uncertainty-in-measurement-significant-figures

Significant Figures and Rounding Rules

Significant figures and rounding rules help students report measurements with the right level of certainty. A measurement includes every digit that was actually measured, including the last uncertain digit. That is why a value can look simple but still carry useful information about the tool used to measure it. Zero can also be significant when it is part of a measured value. For example, if a scale reads 140 pounds to the nearest pound, the 1, 4, and 0 are all significant. Reporting...

key terms and concepts

Learn how matter is classified into elements, compounds, and mixtures. Explore pure substances, solutions, and examples like sports drink and Italian dressing.

Matter: Elements, Compounds, and Mixtures | 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.

Matter and its Interactions

PS.Chm.1.1

Physical Science

PS.PSc.1.1

PS.PSc.1.3

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Study Of Matter

Classification of matter

Physical Geology

Minerals

Crystallinity (crystal structure)

Virginia  Standards of Learning

HIgh School

CH.7

CH.7.a

Earth Science

ES.4

ES.4.a

PS.3

PS.3.a

Arizona Science Standards

High School

Earth and Space Science

HS.E1

HS.E1U1.12

HS.E1U1.13

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

Earth's Place in the Universe

HS-ESS1-2

Texas Essential Knowledge and Skills

CHEM.2

CHEM.2.A

Alabama Course of Study Science

Matter and Its Interactions

9-12.PS.3.5

9-12.PS.3.5.a

Next Generation Science Standards

HS-PS1-5

HS-PS1-4

Chemistry and Physics

IPC.7

IPC.7.C

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

C-PS1-1

C-PS1-2

Earth and Space Science (ESS)

Earth’s Systems

E-ESS2-2.

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Chemical Reactions

HS-PS1-2.

Georgia Standards of Excellence

SPS5.

States of Matter

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, ...

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

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 ...

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, ...

surface-tension-capillary-action-and-viscosity

Surface Tension, Capillary Action, and Viscosity

Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded ...

States of Matter and Phase Changes

The internal energy of a substance&#8212;the total kinetic energy of all its molecules and the potential energy of their associated forces&#8212;depends ...

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 ...

phase-transitions-vaporization-and-condensation

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 explain how changes in energy affect the arrangement and movement of the particles in solids, liquids, and gases, as well as the relative strengths of their intermolecular forces.

Energy Basics

Chemical reactions, such as those that occur when you light a match, involve changes in energy as well as matter.

Chemical changes and their accompanying ...

First Law of Thermodynamics

Energy Conservation

Energy can be converted from one form into another, but all of the energy present before a change occurs always exists in some form ...

Internal Energy

The total of all possible kinds of energy present in a substance is called the internal energy (U), sometimes symbolized as E. Suppose a system with ...

Quantifying Heat

Thermal Energy&#160;

Microscopically, thermal energy is the kinetic energy associated with the random motion of atoms and molecules. Temperature is a ...

Quantifying Work

As a system undergoes a change, its internal energy can change, and energy can be transferred from the system to the surroundings, or from the ...

Enthalpy

Chemists ordinarily use a property known as enthalpy (H) to describe the thermodynamics of chemical and physical processes. Enthalpy is defined as the sum ...

Thermochemical Equations

For a chemical reaction (the system) carried out at constant pressure &ndash; with the only work done caused by expansion or contraction &ndash; the ...

Constant Pressure Calorimetry

Calorimetry is a technique used to measure the amount of heat involved in a chemical or physical process or to measure the heat transferred to or from a ...

Constant Volume Calorimetry

Calorimeters are useful to determine the heat released or absorbed by a chemical reaction. Coffee cup calorimeters are designed to operate at constant ...

using-differential-scanning-calorimetry-to-measure-changes-in-enthalpy

Using Differential Scanning Calorimetry to Measure Changes in Enthalpy

Source: Laboratory of Dr. Terry Tritt &#8212; Clemson University
Differential Scanning Calorimetry (DSC) is a method of thermodynamic analysis based on ...

Hess's Law

There are two ways to determine the amount of heat involved in a chemical change: measure it experimentally, or calculate it from other experimentally ...

Standard Enthalpy of Formation

Enthalpy changes are typically tabulated for reactions in which both the reactants and products are at the same conditions. A standard state is a commonly ...

Enthalpies of Reaction

Hess&rsquo;s law can be used to determine the enthalpy change of any reaction if the corresponding enthalpies of formation of the reactants and products ...

Use mathematics and computational thinking to execute simple calorimetric calculations based on the Law of Conservation of Energy.

PS.Chm.7.2

definition-measurement-pressure-atmospheric-pressure-barometer

Definition and Measurement of Pressure: Atmospheric Pressure, Barometer, and Manometer

Gas pressure is caused by force exerted by gas molecules colliding with the surfaces of objects. Although the force of each collision is very small, any ...

gas-laws-boyle-s-gay-lussac-charles-avogadro-s-and-ideal-gas-law

Gas Laws: Boyle's, Gay-Lussac, Charles', Avogadro's, and Ideal Gas Law

Through experiments, scientists established the mathematical relationships between pairs of variables, such as pressure and temperature, pressure and ...

applications-of-the-ideal-gas-law-molar-mass-density-and-volume

Applications of the Ideal Gas Law: Molar Mass, Density, and Volume

The volume occupied by one mole of a substance is its molar volume. The ideal gas law, PV = nRT, &nbsp;suggests that the volume of a given quantity of gas ...

Use mathematics and computational thinking to explain the relationships among pressure, temperature, volume, and quantity of gas, both qualitatively and quantitatively.

PS.Chm.7.3

Understand the relationship among pressure, temperature, volume, and phase.

Matter: Elements, Compounds, and Mixtures

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