Name: how scientists test a hypothesis
Uploaded: 2020-09-03T13:38:25.000Z
Duration: 3 min 50 s
Channel: JoVE

K12 Standards

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North Carolina K-12 Science Standard Course of Study

9-12

Chemistry

Matter and its Interactions

PS.Chm.1.1

The Scientific Method

الطريقة العلمية هي طريقة منهجية يتبعها جميع التخصصات العلمية. تتبع ستة خطوات رئيسية:الملاحظات،الإستفسارات،بناء الفرضية تنفيذ التجربة،ترجمة المعلومات،وأخيراًالوصول إلى نتيجة تبدأ الطريقة العلمية بالملاحظات وسؤال يساعد على فهم هذه الملاحظات. فعلى سبيل المثال،الكيميائي الفرنسي أنتوني لافوازيه لاحظ ظاهرة الإحتراق.فكون سؤالاًلفهم ما يحدث عندما يحترق شيء. أين تذهب المادة؟الخطوة الثالثة في الطريقة العلمية هي بناء الفرضية والتبرير المؤقت للملاحظات عبر التساؤلات،والتي يمكن إختبارها. للإجابة على سؤال أين تذهب المادة؟إفترض لافوازيه أنه في التفاعل الكيميائي لم تخلق المادة ولم تتدمر.الإفتراضية الجيدة قابلة للتجربة والخطأ. الإفتراضية التي يمكن إختبارها هي الإفتراضية التي تعطي توقعات يمكن إثباتها عن طريق الإختبارات،أو عن طريق الملاحظات. ويمكن تخطئتها حين يتم دحضها بالإختبارات.الخطوة الرابعة في الطريقة العلمية هي الإختبار وتجميع المعلومات. الإختبارات هي ملاحظات،أو مقاييس يتم اجراءها في بيئة يمكن التحكم بها كالحرارة،والضغط،والحجم. هذه الخطوة تفحس كيف يمكن للعالم الحقيقي أن يتناسب مع المتوقع من الفرضية.بعض التجارب والملاحظات تكون نوعية،تصف كيف تحدث العملية. وأخرى كمية،تقيس أو تحدد كمية شيء في العملية. اختبر لافوازيه نظريته عبر تسخين الزئبق في مكان مغلق.و قد أدى هذا إلى تكوين مادة حمراء. وكانت تجاربه من النوع الكمي،لذلك فقد قام بتسجيل الكتلة بحرص للمتفاعلات والنواتج في نظام مغلق وبشكل منفصل. الخطوة الخامسة هي ترجمة المعلومات وتحليلها وتقييم ما إذا كانت النتائج داعمه أو داحضه للفرضية،وما إذا كان هناك حاجه للمزيد من التجارب.لاحظ لافوازيه أن الكتله الكلية للإناء ومكوناته قبل وبعد التفاعلات لا تتغير،رغم أن كتلة الناتج الأحمر كان أكبر من الكتلة الأصلية للزئبق. الخطوة الأخيرة هي رسم استنتاج منطقي وإتخاذ قرار بقبول أو رفض الفرضية. فإذا كانت النتائج تدعم الفرضية بقوة،يتم قبولها.ويمكن أن تعرض للمزيد من الاختبار،أو اعادة التفكير فيها عبر تقديم سؤال جديد،والقيام بتجربة جديده. توصل لافوزييه من خلال تجربته إلى بماأن كتلة الإناء الكلية لم تتغير خلال التفاعلات،فإنّالأوكسجين في الإناء قد إتحد مع الزئبق لتكوين منتج جديد،والذي يعرف الآن بأكسيد الزئبق الثنائي. وهذه الاستنتاج دعم بشكل قوي فرضيته عن حفظ الكتلة،حيث أن الكتله الكلية لشيئ لا تتغير خلال عملية الحرق.ولكن في حال لم تثبت الفرضية،يمكن للعلماء تكوين فرضية جديده بأخذ دلائل من التجرية الخاطئة،والبدء في تجربة جديده. على الرغم من أننا نرى الطريقة العلمية على أنها سلسلة من الخطوات،فالمعلومات الجديدة والأفكار يمكن أن تجعل العالم يتراجع ويعيد بعض الخطوات خلال أي مرحلة من العملية. ولذلك فإن الطريقة العلمية هي عملية ترابطية

الطريقة العلميّة

إن الكيمياء علم تجريبي. يطرح العلماء غالباً أسئلة لفهم الكيمياء في الحياة اليومية ويبحثون عن إجابات لهذه الأسئلة. لتحقيق هذه الغاية، يتبع العلماء سلسلة محددة من الخطوات التي تشكل معاً مايسمى بالمنهج العلمية. يتضمن هذا النهج إجراء ملاحظات، وطرح أسئلة، وبناء فرضية، وإجراء تجارب، وتحليل نتائج، وصياغة استنتاج.  <h4>الملاحظة والسؤال </h4>تتمثل الخطوة الأولى في المنهج العلمي في ملاحظة ظاهرةٍ ما في العالم المادي. بعد ذلك، يتم طرح سؤال لفهم هذه الظاهرة على نحو أفضل. على سبيل المثال، قد يكون السؤال كالتالي: “ أيهما يتجمّد بشكل أسرع، الماء العادي، أم الماء المضاف إليه الملح؟ ”<h4>الفرضية </h4> تتمثّل الخطوة التالية في صياغة تفسير للملاحظة المحددة. يسمى هذا التفسير المبدئي لمجموعة من الملاحظات التي تعمل كدليل لفهم الظاهرة الملاحظة بالفرضية. على سبيل المثال، بالنسبة للسؤال السابق، يمكن أن تقترح الفرضية إلى أن إضافة الملح يغير نقطة تجمد الماء العادي. غالباً ما يستخدم العلماء الأبحاث والأدبيات السابقة لبدء استقصاءهم وصياغة فرضية يمكن اختبارها من خلال التجارب. إن الفرضية القوية قابلة للاختبار وقابلة للدحض على حد سواء. تعتبر قابلة للاختبار إذا كان من الممكن إثبات صحتها وقابلة للدحض إذا كان من الممكن إثبات بطلانها; &mdashوفي هذه الحالة، يجب على العالِم تعديل الفرضية أو تجاهلها.  <h4>التجريب  </h4>الخطوة الثالثة هي تصميم وإجراء التجارب لاختبار صحة الفرضية. التجارب هي القياسات والملاحظات التي يتم تنفيذها في ظل ظروف خاضعة للرقابة. تكون بعض الملاحظات والتجارب نوعية (تصف كيفية حدوث عملية ما)، في حين أن العديد منها كمّي (قياس أو تحديد كمّي لشيء ما عن العملية). لاختبار فرضية الماء المالح، يمكن للعالِم أخذ كوبين بكميات متساوية من الماء، في درجة حرارة الغرفة. يمكن إضافة ملعقة من الملح إلى أحد الكوبين، ووضع كلا الكوبين في الثلاجة. يمكن ملاحظة حالة الماء في كل كوب كل 15 دقيقة ويمكن تسجيل الوقت الذي يستغرقه كل كوب من الماء حتى يتجمّد تماماً.   يعتبر المخطط التجريبي خطوة مهمة في المنهج العلمي. ينبغي توجب الحرص للتحكم في عدد العوامل المتغيرة بحيث يمكن مراقبة تأثير العامل المعين قيد البحث.  <h4>تحليل النتيجة والاستنتاج </h4> تتمثل الخطوة التالية في تحليل نتائج التجارب واستنتاج ما إذا كانت هذه النتائج تثبت صحة الفرضية أم لا. إذا تم إثبات صحتها، فسيتم قبول الفرضية وقد يتم إخضاعها لمزيد من التجارب للإجابة عن أسئلة جديدة. عندما يتم إثبات خطأ الفرضية، فمن الممكن اقتراح فرضية جديدة، والعملية تستمر.  في مثال المياه المالحة، تشير النتائج إلى أن الماء المالح يستغرق تجميده وقتًا أطول من الماء العادي. هذا من شأنه أن يقدّم استنتاجاً مفاده أن الماء الذي يحتوي على ملح يتجمد بمعدل أبطأ من الماء العادي. وبالتالي، فإن النتائج تثبت صحة الفرضية. هذا النص مأخوذ من <a href="https://openstax.org/books/chemistry-2e/pages/1-1-chemistry-in-context">Openstax, Chemistry 2e, Section 1.1: The Scientific Method.</a>

الكيمياء علم تجريبي. غالبا ما يطرح العلماء أسئلة لفهم الكيمياء في الحياة اليومية والبحث عن إجابات لهذه الأسئلة. ل...

Education

JoVE Core

الكيمياء

واحد

Introduction: Matter and Measurement

مقدمة: المادة والقياس

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

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 evidence, and falsifiable, meaning it can also be proven wrong.

The next step is experimentation. Scientists design and carry out experiments under controlled conditions to test the hypothesis. These tests can include qualitative observations, which describe how a process happens, and quantitative measurements, which record how much or how long something changes.

A clear example is the freezing of plain water and salt water. A scientist can place equal amounts of room-temperature water into two glasses, add salt to one glass, and put both in a freezer. By checking the glasses every 15 minutes and recording the time until each one freezes, the scientist can compare the results while keeping other variables controlled.

After the experiment, the results are analyzed and used to form a conclusion. If the data support the hypothesis, it may be accepted and tested further with new questions. If the hypothesis is not supported, a new one can be proposed and the process begins again. In the salt-water example, the results show that salt water freezes more slowly than plain water, so the hypothesis is validated.

How Scientists Test a Hypothesis

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

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: 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...

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

Explore how scientists use observations, hypotheses, controlled experiments, and data analysis to test ideas, using a salt water freezing example.

How Scientists Test a Hypothesis | 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.

Virginia  Standards of Learning

HIgh School

Earth Science

ES.1

ES.1.a

ES.1.f

Life Science

LS.1

LS.1.a

LS.1.f

Physical Science

PS.1

PS.1.f

Physics

PH.1

PH.1.f

Texas Essential Knowledge and Skills

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CHEM.1

CHEM.1.A

CHEM.1.H

Florida Department of Education

Nature of Science

SC.912.N.1

SC.912.N.1.1

SC.912.N.1.2

SC.912.N.2

SC.912.N.2.1

PHYS.4

PHYS.4.A

PHYS.4.B

Chemistry and Physics

IPC.4

IPC.4.A

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. ...

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.

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 ...

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.

How Scientists Test a Hypothesis

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