Chemistry Chapter on Ancient Philosophy and Laws

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Questions and Answers

What did Maharishi Kanad believe about matter?

Maharishi Kanad believed that matter could be divided into smaller pieces.

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

Pakudha Katyayama expanded on Maharishi Kanad's ideas by stating that these particles combine to form different kinds of matter.

What did Democritus and Leucippus believe about dividing matter?

Democritus and Leucippus believed that matter could be divided into smaller pieces.

When did the ideas of Democritus and Leucippus become more widely accepted?

The ideas of Democritus and Leucippus were not scientifically tested until the 18th century. Signup and view all the answers

What was Antoine L. Lavoisier's key contribution to chemistry?

Antoine L. Lavoisier laid the foundation for modern chemistry. Signup and view all the answers

What does the Law of Conservation of Mass state?

The Law of Conservation of Mass states that mass can neither be created nor destroyed in a chemical reaction. Signup and view all the answers

Give an example of the Law of Conservation of Mass in action?

An example is the electrolysis of water, where water (H₂O) is split into hydrogen (H₂) and oxygen (O₂). The total mass of the water before the reaction is the same as the combined mass of the hydrogen and oxygen after the reaction. Signup and view all the answers

What does the Law of Constant Proportions state?

The Law of Constant Proportions states that a particular chemical compound always contains the same elements in the same proportion by mass, regardless of its source or method of preparation. Signup and view all the answers

What is a one-line explanation for the Law of Constant Proportions?

A chemical compound always has the same elements in the same fixed proportion by mass. Signup and view all the answers

Provide an example of the Law of Constant Proportions.

Water (H₂O) always contains hydrogen and oxygen in a mass ratio of 1:8. This ratio remains constant, regardless of the origin of the water. Signup and view all the answers

According to Dalton's Atomic Theory, what is all matter made of?

According to Dalton's Atomic Theory, all matter is made of very tiny particles called atoms. Signup and view all the answers

Dalton's Atomic Theory states that atoms can be created or destroyed in chemical reactions.

False (B) Signup and view all the answers

Atoms of the same element are identical in mass and chemical properties.

True (A) Signup and view all the answers

Atoms of different elements have the same mass and chemical properties.

False (B) Signup and view all the answers

How do atoms combine to form compounds?

Atoms combine in the ratio of small whole numbers to form compounds. Signup and view all the answers

What is the significance of the relative number and kinds of atoms in a compound?

The relative number and kinds of atoms are constant in a given compound. Signup and view all the answers

What is a one-line explanation for what atoms are?

Atoms are the tiny, fundamental building blocks of all matter, essential to everything in the world despite their minuscule size. Signup and view all the answers

How are atoms comparable to other building blocks?

Atoms are comparable to bricks in a building or grains of sand in an ant-hill. Signup and view all the answers

Atoms are extremely small, smaller than anything we can easily imagine.

True (A) Signup and view all the answers

Atomic radius is typically measured in millimeters.

False (B) Signup and view all the answers

What is a one-line explanation for element symbols?

Element symbols are derived from their names, using the first one or two letters, and standardized by IUPAC, ensuring each element has a unique symbol. Signup and view all the answers

What was Dalton's contribution to the use of symbols in chemistry?

Dalton was the first to use symbols for elements in a specific sense. Signup and view all the answers

What was Berzelius' suggestion for creating element symbols?

Berzelius suggested that element symbols should be derived from one or two letters of the element's name. Signup and view all the answers

The first letter in an element symbol is always lowercase.

False (B) Signup and view all the answers

Give an example of how an element symbol is derived from its Latin name?

An example is the element iron, whose symbol is Fe, derived from the Latin word ferrum. Signup and view all the answers

What is a one-line explanation of atomic mass?

Atomic mass is the relative mass of an atom compared to 1/12th the mass of a Carbon-12 atom. Signup and view all the answers

What concept did Dalton's Atomic Theory introduce?

Dalton's Atomic Theory introduced the concept of atomic mass, proposing that each element has a characteristic atomic mass. Signup and view all the answers

How does the concept of atomic mass relate to the Law of Constant Proportions?

The concept of atomic mass helps explain the Law of Constant Proportions by providing a basis for understanding the relative proportions of elements in compounds. Signup and view all the answers

What is the difference between individual atomic masses and relative atomic masses?

Individual atomic masses are difficult to measure directly, while relative atomic masses are determined using laws of chemical combinations. Signup and view all the answers

Why was Carbon-12 chosen as the standard reference for atomic mass in 1961?

Carbon-12 was chosen as the standard reference due to its relatively common availability and the fact that its atomic mass is close to a whole number (12 units). Signup and view all the answers

What is a one-line explanation for molecules of elements?

Molecules of elements consist of identical atoms, ranging from single-atom molecules to complex structures with many atoms, with their atomicity indicating the number of atoms in each molecule. Signup and view all the answers

In what ways can molecules of elements be classified?

Molecules of elements can be classified as single-atom molecules, diatomic molecules, or triatomic molecules. Signup and view all the answers

Give an example of a single-atom molecule.

An example of a single-atom molecule is helium (He). Signup and view all the answers

Give an example of a diatomic molecule.

An example of a diatomic molecule is oxygen (O₂). Signup and view all the answers

What is the definition of atomicity?

Atomicity is the number of atoms in a molecule. Signup and view all the answers

What is a one-line explanation for molecules of compounds?

Molecules of compounds are formed by atoms of different elements combining in definite mass ratios. Signup and view all the answers

What is the main element in water (H2O) and what is its combining ratio by mass?

The main elements in water are hydrogen and oxygen, with a combining ratio by mass of 1:8. Signup and view all the answers

What are the main elements in ammonia (NH3) and what is its combining ratio by mass?

The main elements in ammonia are nitrogen and hydrogen, with a combining ratio by mass of 14:3. Signup and view all the answers

What are the main elements in carbon dioxide (CO2) and what is its combining ratio by mass?

The main elements in carbon dioxide are carbon and oxygen, with a combining ratio by mass of 3:8. Signup and view all the answers

What is a one-line explanation for ions?

Ions are charged particles that can be single atoms or groups of atoms, with negatively charged ions called anions and positively charged ions called cations. Signup and view all the answers

What is the definition of an ion?

Ions are charged species in compounds of metals and nonmetals, and can be a single charged atom or a group of atoms with a net charge. Signup and view all the answers

Anions are positively charged ions.

False (B) Signup and view all the answers

Give an example of a polyatomic ion.

An example of a polyatomic ion is the sulfate ion (SO₄²⁻). Signup and view all the answers

What is a one-line explanation for writing chemical formulae?

The chemical formula of a compound represents its composition using element symbols and valencies, with rules for balancing charges, order of elements, and notation for polyatomic ions. Signup and view all the answers

What is the definition of a chemical formula?

A chemical formula is a symbolic representation of a compound's composition. Signup and view all the answers

What is valency and how is it used?

Valency is the combining power or capacity of an element and is used to determine how atoms of different elements combine. Signup and view all the answers

What is the analogy for understanding valency?

Valency can be thought of as the "arms" of an atom. For example, an octopus with 8 arms and humans with 2 arms. Signup and view all the answers

What is a one-line explanation for molecular mass?

Molecular mass is the sum of the atomic masses of all atoms in a molecule. Signup and view all the answers

What is the definition of molecular mass?

Molecular mass is the sum of atomic masses of all atoms in a molecule. Signup and view all the answers

What is the purpose of expressing molecular mass in atomic mass units?

Expressing molecular mass in atomic mass units provides a relative measure of a molecule's mass compared to other molecules. Signup and view all the answers

What is a one-line explanation for formula unit mass?

Formula unit mass is the sum of atomic masses in a formula unit of an ionic compound. Signup and view all the answers

How does the calculation of formula unit mass relate to molecular mass?

The calculation of formula unit mass is similar to molecular mass, involving the summation of atomic masses of the atoms present in the formula unit. Signup and view all the answers

What is the difference between molecular mass and formula unit mass?

Molecular mass applies to molecular compounds, while formula unit mass applies to ionic compounds. Signup and view all the answers

When is molecular mass used?

Molecular mass is used for substances whose constituent particles are molecules. Signup and view all the answers

When is formula unit mass used?

Formula unit mass is used for substances whose constituent particles are ions. Signup and view all the answers

What is the usage of molecular mass?

Molecular mass is used to calculate the mass of a single molecule of a substance. Signup and view all the answers

Give an example of how to calculate the formula unit mass of calcium chloride (CaCl2).

The formula unit mass of calcium chloride (CaCl₂) can be calculated by adding the atomic mass of calcium (Ca) which is 40 u, and twice the atomic mass of chlorine (Cl) which is 35.5 u. This gives a total formula unit mass of 111 u. Signup and view all the answers

Give an example of how to calculate the formula unit mass of sodium chloride (NaCl).

The formula unit mass of sodium chloride (NaCl) can be calculated by adding the atomic mass of sodium (Na) which is 23 u, and the atomic mass of chlorine (Cl) which is 35.5 u. This gives a formula unit mass of 58.5 u. Signup and view all the answers

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