Democritus and Atomic Theory

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Questions and Answers

What is the main reason for putting a cork on the mouth of the flask?

To prevent the escape of gases produced during the reaction (correct)

To allow for easy mixing of the solutions

To make it easier to weigh the flask

To prevent the solutions from mixing

Who established the foundation of chemical sciences by establishing two important laws of chemical combination?

Democritus

Dalton and Lavoisier

John Dalton

Antoine Lavoisier (correct)

What is the significance of weighing the flask with its contents before and after mixing the solutions?

To measure the volume of the solutions

To demonstrate the law of conservation of mass (correct)

To determine the pH of the solutions

To measure the temperature of the solutions

What is the term used by Democritus to describe the indivisible particles?

Atoms Signup and view all the answers

Who was born in a poor weaver's family in England in 1766?

John Dalton Signup and view all the answers

What is the main objective of mixing the solutions X and Y?

To initiate a chemical reaction Signup and view all the answers

What is the term used to describe the combination of elements in a fixed proportion?

Law of Definite Proportions Signup and view all the answers

Why did scientists in the eighteenth century become interested in finding out how and why elements combine?

To understand the difference between elements and compounds Signup and view all the answers

What is the atomicity of oxygen?

Diatomic Signup and view all the answers

What is the ratio of hydrogen to oxygen in a water molecule?

2:1 Signup and view all the answers

What is the term for a group of atoms that have a net charge on them?

Ion Signup and view all the answers

What type of element is argon?

Non-metal Signup and view all the answers

What is the simplest ratio of hydrogen to oxygen in a water molecule?

1:1 Signup and view all the answers

What is the atomicity of phosphorus?

Tetra-atomic Signup and view all the answers

What type of compounds contain charged species?

Compounds composed of metals and non-metals Signup and view all the answers

What is the atomicity of sulphur?

Poly-atomic Signup and view all the answers

What is the ratio of elements in a chemical substance by mass according to the law of constant proportions?

14:3 Signup and view all the answers

What is the main idea behind Dalton's atomic theory?

Atoms are the smallest particles of matter. Signup and view all the answers

Which of the following is a postulate of Dalton's atomic theory?

Atoms of different elements have different masses and chemical properties. Signup and view all the answers

What is the significance of the law of constant proportions?

It provides an explanation for the law of chemical combination. Signup and view all the answers

What is the name of the British chemist who provided the basic theory about the nature of matter?

John Dalton Signup and view all the answers

What is the result of the reaction between 5.3 g of sodium carbonate and 6 g of acetic acid?

2.2 g of carbon dioxide, 0.9 g of water and 8.2 g of sodium acetate Signup and view all the answers

What is the significance of Dalton's atomic theory in the context of the law of chemical combination?

It explains why elements combine in the ratio of small whole numbers. Signup and view all the answers

What is the idea behind the concept of 'atoms' in Dalton's atomic theory?

Atoms are the smallest particles of matter that can combine to form compounds. Signup and view all the answers

What is the term given to the simplest compounds made up of two different elements?

Binary compounds Signup and view all the answers

What is the purpose of crossovering the valencies of the combining atoms when writing the chemical formulae for compounds?

To balance the positive and negative charges Signup and view all the answers

What is the valency of the magnesium ion in magnesium chloride?

Mg2+ Signup and view all the answers

What is the formula for aluminium oxide?

Al2O3 Signup and view all the answers

What is the formula for calcium oxide?

CaO Signup and view all the answers

Why do we simplify the formula Ca2O2 to CaO?

To make the formula shorter Signup and view all the answers

What is the formula of sodium carbonate?

Na2CO3 Signup and view all the answers

What is the formula of ammonium sulphate?

(NH4)2SO4 Signup and view all the answers

What is the formula unit mass of a substance?

The sum of the atomic masses of all atoms in a formula unit Signup and view all the answers

What is the formula of sodium oxide?

Na2O Signup and view all the answers

What is the formula of aluminium chloride?

AlCl3 Signup and view all the answers

What is the formula of sodium sulphide?

Na2S Signup and view all the answers

What is the formula of magnesium hydroxide?

Mg(OH)2 Signup and view all the answers

How is the formula unit mass of a compound calculated?

By adding the atomic masses of all atoms in a formula unit Signup and view all the answers

डालतन के परमाणु सिद्धांत का आधार क्या था?

रासायनिक संयोजन के नियम Signup and view all the answers

डालतन ने किसका नाम अपने सिद्धांत में उपयोग किया?

ग्रीक Signup and view all the answers

डालतन के सिद्धांत ने किस कानून की व्याख्या प्रदान की?

निश्चित अनुपात का कानून Signup and view all the answers

रासायनिक संयोजन के नियमों का क्या महत्व है?

यह रासायनिक संयोजन में अवयवों की मात्रा की व्याख्या प्रदान करता है Signup and view all the answers

डालतन ने किसके द्वारा दिये गये विचार का विकास किया?

डेमॉक्रिटस Signup and view all the answers

डालतन के परमाणु सिद्धांत के अनुसार, एक तत्व के परमाणु क्या होते हैं?

समान रासायनिक गुणों के Signup and view all the answers

निश्चित अनुपात के कानून के अनुसार, एक रासायनिक संयोजन में अवयव क्या होते हैं?

निश्चित अनुपात में Signup and view all the answers

डालतन के परमाणु सिद्धांत ने किसका विरोध किया?

मात्रा सिद्धांत के विरोध में Signup and view all the answers

प्रस्तुत संकल्पना में ऑक्सिजन के परमाणुओं की संख्या क्या होती है?

2 Signup and view all the answers

कार्बन के परमाणुओं की संरचना कैसी होती है?

अनिश्चित संख्या में परमाणुओं की संरचना Signup and view all the answers

नाइट्रोजन और हाइड्रोजन के परमाणुओं की संख्या का अनुपात क्या होता है?

14:3 Signup and view all the answers

ऑक्सिजन के तीन परमाणुओं से मिलकर क्या बनता है?

ओजोन Signup and view all the answers

कौन सा तत्व सरल संरचना नहीं होती है?

कार्बन Signup and view all the answers

किन तत्वों के परमाणुओं की संख्या का अनुपात निश्चित होता है?

सभी तत्व Signup and view all the answers

सोडियम कार्बोनेट का आणविक द्रव्यमान क्या होगा?

44u Signup and view all the answers

निम्नलिखित में से कौन सा सूत्र सही है?

AlCl3 Signup and view all the answers

अमोनियम सल्फेट का आणविक द्रव्यमान क्या होगा?

132u Signup and view all the answers

सोडियम ऑक्साइड का सूत्र क्या है?

Na2O Signup and view all the answers

एलुमिनियम क्लोराइड का सूत्र क्या है?

AlCl3 Signup and view all the answers

मैग्नीशियम हाइड्रॉक्साइड का सूत्र क्या है?

Mg(OH)2 Signup and view all the answers

निम्नलिखित में से कौन सा सूत्र सही है?

Na2S Signup and view all the answers

फॉर्मुला यूनिट मास क्या है?

एक पदार्थ का फॉर्मुला यूनिट मास, जो उसके सभी परमाणुओं के द्रव्यमान का योग है Signup and view all the answers

एक आयन का निगेटिवELY चार्ज किया हुआ भाग क्या कहलाता है?

एनियन Signup and view all the answers

सोडियम क्लोराइड (NaCl) में कौन से आयन पाए जाते हैं?

सोडियम आयन (Na+) और क्लोराइड आयन (Cl-) Signup and view all the answers

एक तत्व की संयोजक क्षमता क्या कहलाती है?

वेलेंसी Signup and view all the answers

एक पॉलीएटोमिक आयन क्या होता है?

एक समूह आयन जिसका चार्ज है Signup and view all the answers

कैल्शियम ऑक्साइड में कौन से आयन पाए जाते हैं?

कैल्शियम आयन (Ca2+) और ऑक्साइड आयन (O2-) Signup and view all the answers

एक Element की संयोजक क्षमता क्या होती है?

एक Element की संयोजक क्षमता उसके हाथ या भुजाएं हैं Signup and view all the answers

एक यौगिक में तत्वों का अनुपात क्या होता है?

एक यौगिक में तत्वों का अनुपात निश्चित होता है Signup and view all the answers

एक पॉलीएटोमिक आयन का उदाहरण क्या है?

अमोनियम आयन (NH4+) Signup and view all the answers

आण्विक द्रव्यमान इकाई किस प्रकार परिभाषित की गई है?

एक कार्बन-12 आइसोटोप के द्रव्यमान का 1/12वां हिस्सा Signup and view all the answers

वैज्ञानिकों ने प्रारंभ में आण्विक द्रव्यमान इकाई के रूप में किसका चयन किया था?

आक्सीजन परमाणु Signup and view all the answers

कार्बन-12 आइसोटोप के द्रव्यमान का 1/12वां हिस्सा क्या है?

एक आण्विक द्रव्यमान इकाई Signup and view all the answers

आक्सीजन परमाणु का द्रव्यमान किस वजह से महत्त्वपूर्ण माना गया था?

यह अधिकांश तत्वों के साथ यौगिक बनाता है Signup and view all the answers

फल विक्रेता के उदाहरण में 12 फ्रूट मास यूनिट (फीएमयू) क्या हैं?

एक वाटरमेलन के द्रव्यमान का 1/12वां हिस्सा Signup and view all the answers

आण्विक द्रव्यमान इकाई क्या है?

कार्बन-12 आइसोटोप के द्रव्यमान का 1/12वां हिस्सा Signup and view all the answers

वैज्ञानिकों ने 1961 में क्या चुना था?

कार्बन-12 आइसोटोप के द्रव्यमान को आण्विक द्रव्यमान इकाई के रूप में Signup and view all the answers

परमाणु क्या हैं?

स्वतंत्र रूप से मौजूद तत्व Signup and view all the answers

Study Notes

Atoms and Chemical Combination

Democritus introduced the concept of indivisible particles called atoms, which was later developed by scientists through experimentation and philosophical considerations.
By the end of the 18th century, scientists recognized the difference between elements and compounds and sought to understand how and why elements combine.

Laws of Chemical Combination

Antoine Lavoisier established two important laws of chemical combination:
- Law of Conservation of Mass: Matter cannot be created or destroyed in a chemical reaction.
- Law of Definite Proportions: In a chemical substance, elements are always present in definite proportions by mass.

Dalton's Atomic Theory

John Dalton proposed an atomic theory based on the laws of chemical combination, which stated that:
- Atoms are indivisible particles that make up matter.
- Atoms of a given element are identical in mass and chemical properties.
- Atoms of different elements have different masses and chemical properties.
- Atoms combine in small whole number ratios to form compounds.
- The relative number and kinds of atoms are constant in a given compound.

Atomicity of Elements

The atomicity of some elements is shown in Table 3.3, which indicates the type of element, its atomicity, and atomic mass.

Ions and Compounds

Ions are charged species that can be positively or negatively charged, consisting of a single charged atom or a group of atoms with a net charge.
Compounds composed of metals and non-metals contain ions, where the positive and negative charges must balance each other and the overall structure must be neutral.
Examples of formulae for simple compounds include hydrogen chloride (HCl), aluminium oxide (Al2O3), and sodium carbonate (Na2CO3).

Formula Unit Mass

The formula unit mass of a substance is the sum of the atomic masses of all atoms in a formula unit of a compound.
Formula unit mass is calculated in the same manner as molecular mass.

Writing Chemical Formulae

When writing chemical formulae, the constituent elements and their valencies are written, and then the valencies are crossed over to form the compound.
Examples of writing chemical formulae include hydrogen chloride, hydrogen sulphide, and sodium carbonate.

Laws of Chemical Combination

The law of constant proportions states that elements in a chemical substance are always present in definite proportions by mass, regardless of the method or source of obtaining the substance.
Atoms of a given element are identical in mass and chemical properties.
Atoms of different elements have different masses and chemical properties.
Atoms combine in the ratio of small whole numbers to form compounds.

Dalton's Atomic Theory

Dalton's theory provided an explanation for the law of constant proportions.
The theory states that the smallest particles of matter are atoms, which are indivisible and indestructible.
Atoms of different elements have different masses and chemical properties.

Atomic Mass Unit

The atomic mass unit (amu) is a standard unit of mass used to express the mass of an atom.
Initially, the amu was defined as 1/16 of the mass of an atom of naturally occurring oxygen.
Later, the amu was redefined as one-twelfth the mass of an atom of carbon-12.
The relative atomic masses of all elements are found with respect to an atom of carbon-12.

Atomicity of Elements

Metals and some other elements, such as carbon, do not have a simple structure but consist of a large and indefinite number of atoms bonded together.
Non-metals, such as oxygen, nitrogen, and chlorine, have a definite atomicity.

Molecules and Ions

Atoms of different elements join together in definite proportions to form molecules of compounds.
A group of atoms carrying a charge is known as a polyatomic ion.
Ions can be positively charged (cations) or negatively charged (anions).
The combining power (or capacity) of an element is known as its valency.

Formulae of Compounds

Formulae of compounds represent the ratio of atoms of different elements in the compound.
Examples of formulae of compounds include H2O, CO2, NaCl, and Na2CO3.

Molecular Mass and Formula Unit Mass

Molecular mass is the sum of the atomic masses of all atoms in a molecule.
Formula unit mass is the sum of the atomic masses of all atoms in a formula unit of a compound.
Molecular mass and formula unit mass are calculated in the same manner.

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Democritus and Atomic Theory

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Questions and Answers

What is the main reason for putting a cork on the mouth of the flask?

Who established the foundation of chemical sciences by establishing two important laws of chemical combination?

What is the significance of weighing the flask with its contents before and after mixing the solutions?

What is the term used by Democritus to describe the indivisible particles?

Who was born in a poor weaver's family in England in 1766?

What is the main objective of mixing the solutions X and Y?

What is the term used to describe the combination of elements in a fixed proportion?

Why did scientists in the eighteenth century become interested in finding out how and why elements combine?

What is the atomicity of oxygen?

What is the ratio of hydrogen to oxygen in a water molecule?

What is the term for a group of atoms that have a net charge on them?

What type of element is argon?

What is the simplest ratio of hydrogen to oxygen in a water molecule?

What is the atomicity of phosphorus?

What type of compounds contain charged species?

What is the atomicity of sulphur?

What is the ratio of elements in a chemical substance by mass according to the law of constant proportions?

What is the main idea behind Dalton's atomic theory?

Which of the following is a postulate of Dalton's atomic theory?

What is the significance of the law of constant proportions?

What is the name of the British chemist who provided the basic theory about the nature of matter?

What is the result of the reaction between 5.3 g of sodium carbonate and 6 g of acetic acid?

What is the significance of Dalton's atomic theory in the context of the law of chemical combination?

What is the idea behind the concept of 'atoms' in Dalton's atomic theory?

What is the term given to the simplest compounds made up of two different elements?

What is the purpose of crossovering the valencies of the combining atoms when writing the chemical formulae for compounds?

What is the valency of the magnesium ion in magnesium chloride?

What is the formula for aluminium oxide?

What is the formula for calcium oxide?

Why do we simplify the formula Ca2O2 to CaO?

What is the formula of sodium carbonate?

What is the formula of ammonium sulphate?

What is the formula unit mass of a substance?

What is the formula of sodium oxide?

What is the formula of aluminium chloride?

What is the formula of sodium sulphide?

What is the formula of magnesium hydroxide?

How is the formula unit mass of a compound calculated?

डालतन के परमाणु सिद्धांत का आधार क्या था?

डालतन ने किसका नाम अपने सिद्धांत में उपयोग किया?

डालतन के सिद्धांत ने किस कानून की व्याख्या प्रदान की?

रासायनिक संयोजन के नियमों का क्या महत्व है?

डालतन ने किसके द्वारा दिये गये विचार का विकास किया?

डालतन के परमाणु सिद्धांत के अनुसार, एक तत्व के परमाणु क्या होते हैं?

निश्चित अनुपात के कानून के अनुसार, एक रासायनिक संयोजन में अवयव क्या होते हैं?

डालतन के परमाणु सिद्धांत ने किसका विरोध किया?

प्रस्तुत संकल्पना में ऑक्सिजन के परमाणुओं की संख्या क्या होती है?

कार्बन के परमाणुओं की संरचना कैसी होती है?

नाइट्रोजन और हाइड्रोजन के परमाणुओं की संख्या का अनुपात क्या होता है?

ऑक्सिजन के तीन परमाणुओं से मिलकर क्या बनता है?

कौन सा तत्व सरल संरचना नहीं होती है?

किन तत्वों के परमाणुओं की संख्या का अनुपात निश्चित होता है?

सोडियम कार्बोनेट का आणविक द्रव्यमान क्या होगा?

निम्नलिखित में से कौन सा सूत्र सही है?

अमोनियम सल्फेट का आणविक द्रव्यमान क्या होगा?

सोडियम ऑक्साइड का सूत्र क्या है?

एलुमिनियम क्लोराइड का सूत्र क्या है?

मैग्नीशियम हाइड्रॉक्साइड का सूत्र क्या है?

निम्नलिखित में से कौन सा सूत्र सही है?

फॉर्मुला यूनिट मास क्या है?

एक आयन का निगेटिवELY चार्ज किया हुआ भाग क्या कहलाता है?

सोडियम क्लोराइड (NaCl) में कौन से आयन पाए जाते हैं?

एक तत्व की संयोजक क्षमता क्या कहलाती है?

एक पॉलीएटोमिक आयन क्या होता है?

कैल्शियम ऑक्साइड में कौन से आयन पाए जाते हैं?

एक Element की संयोजक क्षमता क्या होती है?

एक यौगिक में तत्वों का अनुपात क्या होता है?

एक पॉलीएटोमिक आयन का उदाहरण क्या है?

आण्विक द्रव्यमान इकाई किस प्रकार परिभाषित की गई है?

वैज्ञानिकों ने प्रारंभ में आण्विक द्रव्यमान इकाई के रूप में किसका चयन किया था?

कार्बन-12 आइसोटोप के द्रव्यमान का 1/12वां हिस्सा क्या है?

आक्सीजन परमाणु का द्रव्यमान किस वजह से महत्त्वपूर्ण माना गया था?

फल विक्रेता के उदाहरण में 12 फ्रूट मास यूनिट (फीएमयू) क्या हैं?

आण्विक द्रव्यमान इकाई क्या है?

वैज्ञानिकों ने 1961 में क्या चुना था?

परमाणु क्या हैं?