Chemistry Chapter 1: Atomic Theories
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Questions and Answers

What is the symbol for Fluorine?

  • Fl
  • Fr
  • F (correct)
  • Fo

Which element uses 'Au' as its symbol?

  • Copper
  • Gold (correct)
  • Silver
  • Iron

What does the one-line explanation about element symbols indicate?

  • They are standardized to ensure uniqueness. (correct)
  • They are based on historical uses.
  • They contain numbers and letters.
  • They are always made of two letters.

Who was the first to use symbols for elements in a scientific context?

<p>John Dalton (C)</p> Signup and view all the answers

What does Dalton's contribution imply about the symbol of an element?

<p>It concisely represents one atom of that element. (A)</p> Signup and view all the answers

What is the symbol for Silver?

<p>Ag (A)</p> Signup and view all the answers

Which element has the symbol 'Na'?

<p>Sodium (D)</p> Signup and view all the answers

What naming convention is used for the symbol 'K'?

<p>Derived from its original Latin name (D)</p> Signup and view all the answers

Which component primarily approves names and symbols of chemical elements?

<p>International Union of Pure and Applied Chemistry (A)</p> Signup and view all the answers

The symbol for Argon is represented as?

<p>Ar (D)</p> Signup and view all the answers

Identify the element with the symbol 'Si'.

<p>Silicon (D)</p> Signup and view all the answers

What is the symbol for Nitrogen?

<p>N (D)</p> Signup and view all the answers

Which of the following elements has a symbol derived from a color name?

<p>Gold (A)</p> Signup and view all the answers

Who established the Law of Conservation of Mass?

<p>Lavoisier (D)</p> Signup and view all the answers

What philosophical contribution did Democritus make?

<p>Matter is made of indivisible particles (C)</p> Signup and view all the answers

According to Lavoisier's findings, what happens to mass during a chemical reaction?

<p>Mass remains constant (B)</p> Signup and view all the answers

What did Maharishi Kanad believe about the smallest particles?

<p>They are called Parmanu (C)</p> Signup and view all the answers

Which law states that mass cannot be created or destroyed?

<p>Law of Conservation of Mass (B)</p> Signup and view all the answers

What is the significance of Joseph L. Proust's contribution?

<p>He formulated the Law of Constant Proportions (A)</p> Signup and view all the answers

What did Pakudha Katyayama add to Maharishi Kanad's ideas?

<p>Particles combine to form different matter (B)</p> Signup and view all the answers

What was a limitation of the ideas presented by ancient Greek philosophers?

<p>They were philosophical and not tested until the 18th century (B)</p> Signup and view all the answers

What is the atomicity of Argon?

<p>Monoatomic (A)</p> Signup and view all the answers

What is the mass by mass ratio of hydrogen to oxygen in water?

<p>1:8 (B)</p> Signup and view all the answers

Which of the following elements is diatomic?

<p>Oxygen (B)</p> Signup and view all the answers

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

<p>2:1 (D)</p> Signup and view all the answers

What type of bonds are formed in molecules of compounds?

<p>Definite mass ratios (C)</p> Signup and view all the answers

How many atoms are present in a tetra-atomic molecule?

<p>Four atoms (D)</p> Signup and view all the answers

What is the atomicity of sulfur?

<p>Poly-atomic (C)</p> Signup and view all the answers

What does the Law of Constant Proportions state about a chemical compound?

<p>It always contains the same elements in the exact same proportion by mass. (D)</p> Signup and view all the answers

Which of the following represents a diatomic element?

<p>Oxygen (A), Nitrogen (B), Hydrogen (C)</p> Signup and view all the answers

Which statement best describes atoms according to the provided content?

<p>Atoms of a given element are identical in mass and chemical properties. (B)</p> Signup and view all the answers

How did Antoine Lavoisier contribute to the field of chemistry?

<p>He established the Law of Conservation of Mass. (C)</p> Signup and view all the answers

How do atoms combine to form compounds, according to the information provided?

<p>In the ratio of small whole numbers. (B)</p> Signup and view all the answers

What validity does the statement 'atoms are indivisible particles' hold in the content provided?

<p>Atoms are fundamental building blocks that cannot be created or destroyed in a reaction. (B)</p> Signup and view all the answers

Which of the following is a characteristic of a pure chemical compound?

<p>It has a constant composition regardless of how it is made. (C)</p> Signup and view all the answers

Which of the following statements is incorrect regarding the properties of atoms?

<p>Atoms can change their mass during chemical reactions. (C)</p> Signup and view all the answers

In the context of chemical reactions, what does it mean when it states that the 'mass of water before the reaction equals the combined mass of hydrogen and oxygen after the reaction'?

<p>Mass is not affected by the chemical reaction. (B)</p> Signup and view all the answers

Which of the following represents a polyatomic ion?

<p>Hydroxide OH- (B)</p> Signup and view all the answers

What is the valency of Aluminium?

<p>3 (C)</p> Signup and view all the answers

Which ion has a valency of 1?

<p>Hydride H- (C)</p> Signup and view all the answers

What does the chemical formula of a compound represent?

<p>The composition using element symbols and valencies (D)</p> Signup and view all the answers

Which of the following ions has a charge of -3?

<p>Nitride N3- (A)</p> Signup and view all the answers

Which element has a valency that matches its charge in its ionic form?

<p>Sodium Na+ (B)</p> Signup and view all the answers

What is the valency of Phosphate in a compound?

<p>3 (B)</p> Signup and view all the answers

Which of the following symbols correctly represents an ion with a positive charge?

<p>Sodium Na+ (C)</p> Signup and view all the answers

Flashcards

Ancient Indian Philosophers

Ancient Indian thinkers who pondered about matter's smallest components.

Maharishi Kanad

Ancient Indian philosopher who proposed the concept of Parmanu.

Parmanu

Smallest particles of matter, according to Maharishi Kanad.

Law of Conservation of Mass

Mass is conserved in a chemical reaction (neither created nor destroyed).

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Chemical Reaction

Process where substances rearrange to form new substances.

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Lavoisier and Proust

Chemists who established the laws of chemical combination through experiments.

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Law of Constant Proportions

In a chemical compound, elements always combine in a fixed ratio by mass.

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Democritus & Leucippus

Ancient Greek philosophers who proposed the concept of atoms.

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Elements

Basic building blocks of matter that cannot be broken down further by chemical means.

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Compounds

Substances formed by the combination of two or more elements in a fixed ratio.

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Atomic Theory - indivisible particles

Atoms are the smallest unit of an element that can take part in a chemical reaction and cannot be further divided.

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Atom - Identical properties

Atoms of the same element share the same properties, including mass.

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Atom - Different elements

Atoms of different elements have different properties and masses.

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Atoms in compounds

Atoms combine in a simple whole-number ratio to form compounds.

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Fixed ratio for compound

A given compound always has the same relative number and types of atoms.

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Element Symbol

A unique one or two letter abbreviation representing a chemical element, standardized by IUPAC.

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IUPAC

International Union of Pure and Applied Chemistry; the organization responsible for standardizing element symbols.

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Dalton's Contribution

John Dalton, the first to use symbols for elements, representing a definite quantity (one atom) of each element.

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1 nm = 10⁻⁹ m

One nanometer (nm) is equal to one billionth of a meter (m).

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1 m = 10⁹ nm

One meter (m) is equal to one billion nanometers (nm).

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Nitrogen Symbol

The symbol for nitrogen is 'N'.

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Oxygen Symbol

The symbol for oxygen is 'O'.

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Potassium Symbol

The symbol for potassium is 'K'.

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Silicon Symbol

The symbol for silicon is 'Si'.

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Silver Symbol

The symbol for silver is 'Ag'.

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Sodium Symbol

The symbol for sodium is 'Na'.

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Sulphur Symbol

The symbol for sulphur is 'S'.

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Atomicity

The number of atoms present in a molecule of an element. For example, the atomicity of oxygen is 2, as there are two oxygen atoms in an oxygen molecule (O2).

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Monoatomic

An element that exists as a single atom. Examples include noble gases like Helium (He) and Argon (Ar).

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Diatomic

An element that exists as a molecule containing two atoms. Examples include oxygen (O2), nitrogen (N2), and hydrogen (H2).

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Polyatomic

An element that exists as a molecule containing more than two atoms. An example is phosphorus (P4).

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What is the ratio by mass of hydrogen to oxygen in water?

The ratio of mass of hydrogen to oxygen in water is 1:8. This means that for every 1 gram of hydrogen, there are 8 grams of oxygen in water.

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What is the ratio by number of atoms of hydrogen to oxygen in water?

The ratio of number of atoms of hydrogen to oxygen in water is 2:1. This means that for every 2 hydrogen atoms, there is 1 oxygen atom in water.

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What is a molecule of a compound?

A molecule of a compound is formed by the combination of atoms of different elements in a fixed ratio. For example, water (H2O) is a compound formed by the combination of hydrogen and oxygen in a 2:1 ratio.

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What is an ion?

An ion is an atom or group of atoms that has gained or lost electrons, resulting in a net electric charge. Ions can be positively charged (cations) or negatively charged (anions).

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What are polyatomic ions?

Groups of atoms that act as a single unit and carry a charge.

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What is valency?

The combining power of an element, which is its ability to gain, lose, or share electrons.

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What is a chemical formula?

A symbolic representation of a compound's composition using element symbols, valencies, and rules for balancing charges and order.

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What is the purpose of a chemical formula?

To represent the composition of a compound by using element symbols and valencies to show the ratio in which elements are combined.

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How do valencies help in writing chemical formulas?

Valencies indicate the combining capacity of elements, determining the number of each atom needed to balance charges and form a neutral compound.

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What is the difference between a monatomic ion and a polyatomic ion?

A monatomic ion is composed of a single atom, while a polyatomic ion comprises multiple atoms acting as a unit with an overall charge.

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How are charges balanced in chemical formulas?

The total positive charge of the cation(s) must equal the total negative charge of the anion(s) to form a neutral compound.

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What is the role of subscripts in chemical formulas?

Subscripts indicate the number of atoms of each element in a molecule.

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Study Notes

Introduction

  • Ancient Indian philosophers, like Maharishi Kanad (500 BC), considered dividing matter into smaller pieces.
  • Pakudha Katyayama furthered this concept.
  • Ancient Greek philosophers, Democritus and Leucippus, proposed the idea of indivisible particles called atoms.
  • 18th Century scientific advancements led to understanding of elements and compounds, and how they combine.
  • Antoine Lavoisier laid the foundation of chemistry.

Laws of Chemical Combination

  • Law of Conservation of Mass: Mass is neither created nor destroyed in a chemical reaction. The total mass remains constant.
  • Law of Constant Proportions: A chemical compound always contains the same elements in the same fixed proportion by mass.

Dalton's Atomic Theory

  • All matter is made of atoms.
  • Atoms of a given element are identical in mass and properties.
  • Atoms of different elements have different masses and properties.
  • Atoms combine in simple whole number ratios to form compounds.
  • Atoms are indivisible in chemical reactions.

Symbols of Atoms

  • Element symbols are derived from their names.
  • Dalton first used symbols for elements.
  • Berzelius suggested using one or two letters from the name.

Atomic Mass

  • Atomic mass is the relative mass of an atom compared to 1/12th the mass of a Carbon-12 atom.
  • Dalton proposed the concept of atomic mass.
  • Atomic mass is used to compare the masses of different atoms.

Molecules of Elements and Compounds

  • Atoms of most elements can't exist independently; they form molecules.
  • Molecules of elements consist of identical atoms.
  • Molecules of compounds are formed by different elements combining in definite mass ratios.

Molecules of Compounds

  • Atoms of different elements combine in definite proportions to form compounds.
  • Examples include water (H₂O), ammonia (NH₃), and carbon dioxide (CO₂).
  • Examples of molecules like water (H2O), ammonia (NH3), and carbon dioxide (CO2) are included to showcase combining ratios in compounds.

Formula Unit Mass

  • Formula unit mass is the sum of atomic masses in a formula unit.
  • It's similar to molecular mass but used for ionic compounds.
  • Calculated by adding atomic masses of each atom in the formula unit.

Molecular Mass

  • Molecular mass is the sum of atomic masses of all atoms in a molecule.
  • Calculated by adding atomic masses of each atom in the molecule.
  • Unit is atomic mass units (u).

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Description

Explore the foundational concepts of chemistry in this quiz covering ancient philosophies and essential laws of chemical combination. Delve into the origins of atomic theory, including contributions from figures like Maharishi Kanad and Antoine Lavoisier. Test your understanding of laws governing mass and proportions in chemical reactions.

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