Questions and Answers
What is the correct chemical symbol for sodium?
The symbol for cobalt is CO.
False
What is the latest abbreviation for atomic mass unit as recommended by IUPAC?
u
The chemical symbol for chlorine is ______.
Signup and view all the answers
Match the following elements with their symbols:
Signup and view all the answers
What is the formula for magnesium chloride?
Signup and view all the answers
The bracket is required when indicating one polyatomic ion in a chemical formula.
Signup and view all the answers
What is the formula for sodium nitrate?
Signup and view all the answers
In the compound magnesium chloride, there are ___ chloride ions for each magnesium ion.
Signup and view all the answers
Match the following compounds with their formulas:
Signup and view all the answers
How do you simplify the formula Ca2O2?
Signup and view all the answers
In binary compounds, the charges on the ions must balance each other.
Signup and view all the answers
The formula for hydrogen chloride is ___ .
Signup and view all the answers
Who postulated the idea of dividing matter into smaller particles known as Parmanu?
Signup and view all the answers
The concept of indivisible particles called atoms was introduced by Paul Dirac.
Signup and view all the answers
What does the term 'atom' mean?
Signup and view all the answers
According to the ancient philosophers of India, if matter is divided, we will eventually reach the smallest particles called __________.
Signup and view all the answers
Match the following philosophers with their contributions:
Signup and view all the answers
What was the main focus of ancient Indian and Greek philosophers regarding matter?
Signup and view all the answers
The law of conservation of mass states that mass can be created during a chemical reaction.
Signup and view all the answers
The ancient philosopher who suggested that matter cannot be divided further is __________.
Signup and view all the answers
What is the correct chemical formula for calcium hydroxide?
Signup and view all the answers
The molecular mass of water is equal to 18 atomic mass units.
Signup and view all the answers
How many hydrogen atoms are present in one molecule of ammonium sulfate, (NH4)2SO4?
Signup and view all the answers
The molecular mass of nitric acid (HNO3) is ____ u.
Signup and view all the answers
Which of the following describes the concept of molecular mass?
Signup and view all the answers
In the molecular formula Na2CO3, brackets are required for the carbonate ion.
Signup and view all the answers
Calculate the molecular mass of calcium hydroxide, Ca(OH)2.
Signup and view all the answers
Match the chemical formulas on the left with their common names on the right:
Signup and view all the answers
What is the smallest particle of an element that cannot usually exist independently?
Signup and view all the answers
A molecule can exist independently and shows all the properties of the substance.
Signup and view all the answers
What is a polyatomic ion?
Signup and view all the answers
The chemical formula of a compound shows its constituent elements and the number of _____ of each combining element.
Signup and view all the answers
Match the following compounds with their chemical formulae:
Signup and view all the answers
When 3.0 g of carbon is burned in 8.00 g of oxygen, which law of chemical combination is demonstrated?
Signup and view all the answers
In ionic compounds, the chemical formula is determined by the mass of the ions present.
Signup and view all the answers
List two examples of polyatomic ions.
Signup and view all the answers
Study Notes
Chemical Formulas and Ionic Compounds
- Magnesium chloride has the chemical formula MgCl2, indicating two chloride ions per magnesium ion.
- Chemical formulas are written by combining the symbols of the elements and their respective valencies.
- When multiple identical polyatomic ions are present, their formula is enclosed in brackets with a subscript indicating quantity.
Binary Compounds
- Binary compounds consist of two different elements.
- Valencies can be crossed over to determine the formula; for example, calcium oxide simplifies from Ca2O2 to CaO.
Notable Examples
- Hydrogen chloride: HCl
- Aluminum oxide: Al2O3
- Calcium hydroxide: Ca(OH)2, depicting two hydroxyl groups.
- Sodium nitrate: NaNO3
- Sodium carbonate: Na2CO3
- Ammonium sulfate: (NH4)2SO4
Molecular Mass
- Molecular mass refers to the sum of atomic masses of all atoms in a molecule, expressed in atomic mass units (u).
- Example calculations show water (H2O) has a molecular mass of 18 u; HNO3 totals 63 u.
Historical Context of Matter
- Ancient philosophers theorized about the divisibility of matter; the concept of 'Parmanu' by Maharishi Kanad represents the smallest particles.
- The term "atom" was coined by Democritus, meaning "indivisible".
Modern Chemistry Foundations
- The law of conservation of mass states that mass remains constant during a chemical reaction.
- Chemical formulas identify both the elements and their quantities in a compound.
Polyatomic Ions
- Polyatomic ions are clusters of atoms that carry a fixed charge.
- Formulae include brackets when multiple identical units are present; e.g., in calcium hydroxide, brackets indicate two hydroxyl ions.
Exercises on Understanding Chemistry
- Weight composition and mass calculations in chemical reactions exemplify practical applications of the laws of chemical combinations.
Group Activity Suggestion
- Create a fun placard game to reinforce knowledge of the symbols, valencies, and formulae of elements.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Dive into the chemical composition of magnesium chloride in this quiz. Learn about the ionic structure and how to represent formulas with polyatomic ions. Test your understanding of chemical formulas and ionic bonds.
