ATOMS AND MOLECLUES in 1 Shot || FULL Chapter Coverage (Concepts+PYQs) || Class 9th Chemisty
Physics Wallah Foundation・83 minutes read
Atoms are the smallest indivisible particles of matter, combining in fixed ratios to form compounds. Dalton's Atomic Theory, while incorrect on some points, laid the foundation for our understanding of atomic structure and chemical reactions.
Insights
- Atoms are the smallest particles that make up matter and cannot be created, destroyed, or divided further by chemical reactions.
- The Law of Conservation of Mass states that the total mass of reactants equals the total mass of products in a chemical reaction, ensuring mass is conserved.
- Dalton's Atomic Theory, while groundbreaking, had limitations such as the indivisibility of atoms, which can be divided into subatomic particles like protons, neutrons, and electrons.
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Recent questions
What is Dalton's Atomic Theory?
Dalton's Atomic Theory posits that all matter is made up of indivisible atoms, with atoms of a given element having identical mass and chemical properties. Atoms of different elements exhibit varying mass and chemical properties, combining in small whole number ratios to form compounds. Dalton's theory emphasizes that atoms cannot be divided into halves and do not combine as fractions, with the relative number and kinds of atoms remaining constant in a given compound.
How are elements represented by symbols?
Elements are represented by symbols derived from their names, with the first letter capitalized and the second in lowercase. The symbols were proposed by JJ Bergius, using the first letter and another letter of the element's name. The International Union of Pure and Applied Chemistry approves the names of elements, their symbols, and units to standardize symbols. Symbols do not have to be based on English names and can be from other languages, like Latin. For example, the symbol for helium is "He," and the symbol for potassium is "K."
What is the Law of Conservation of Mass?
The Law of Conservation of Mass states that the total mass of reactants equals the total mass of products in a chemical reaction. This law asserts that mass is neither created nor destroyed during a chemical reaction, highlighting the importance of balancing chemical equations to ensure the conservation of mass.
How are molecules classified based on atomicity?
Molecules are classified based on atomicity, referring to the number of atoms present in a molecule. Molecules can be monoatomic, diatomic, triatomic, tetraatomic, or polyatomic, depending on the number of atoms they contain. The molecular mass of a molecule is the sum of the masses of all atoms in the molecule, calculated by adding the masses of each atom present in the compound.
What is valency in chemistry?
Valency is the combining capacity of atoms to achieve stability, determined by the number of electrons lost, gained, or shared by an atom. It remains the same for an atom regardless of how it achieves stability and helps determine how atoms combine to form molecules. Valency plays a crucial role in understanding how elements combine with each other to form chemical compounds, influencing the composition and properties of the resulting substances.
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