atom, elements, molecule and compounds #CBSE, #IX class, #chapter-3, #ATOMS&MOLECULES,

#cbseclass-9th, #atomsand molecules, #Classification, of Matter
Matter can be classified into pure substances and mixtures:

Pure Substances

Elements: Consist of only one type of atom (e.g., Iron (Fe), Nitrogen (N2)).
Compounds: Consist of two or more types of atoms chemically bonded in a fixed ratio (e.g., Water (H2O), Carbon dioxide (CO2)).
Mixtures

Homogeneous Mixtures (Solutions): Uniform composition throughout (e.g., Saltwater, Air).
Heterogeneous Mixtures: Non-uniform composition, components are distinguishable (e.g., Salad, Sand and iron filings).
Atom
Definition: The smallest unit of matter that retains the identity of a chemical element. Example: A single helium atom.Element
Definition: A pure substance consisting of only one type of atom, distinguished by its atomic number (the number of protons in the nucleus).Example: Oxygen (02)Molecule
Definition: Two or more atoms chemically bonded together. Molecules can consist of atoms of the same element or different elements.
Types:
Diatomic Molecules: Two atoms, either of the same element (e.g., 02)or different elements (e.g.,
CO).
Polyatomic Molecules: More than two atoms
Example: Water (H2O), Carbon dioxide (CO2). Compound
Definition: A substance formed when two or more different types of atoms chemically bond in a fixed ratio.
Properties: Compounds have properties different from their constituent elements.
Example: Sodium chloride (NaCl), Glucose (C6H12O6).
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1. 1 The essence of matter Definition: Anything that has mass and occupies space is called matter .

2. 2 Matter (Solid, liquid, Gas) Mixtures Pure substances Heterogeneous Homogeneous Aerosols Cigarette smoke Water spray Car exhaust Gas mixtures Air Protective gas Superheated steam Compounds Water (H2O) Carbon dioxide (CO2) Alloys Brass Bronze solder Solutions Sugar water Carbonated soda Elements Hydrogen (H) Iron (Fe) Carbon (C) Solid sol Iron ore Granite marble Emulsions Oil water Milk mayonnaise suspensions Iron sludge Quicksand Liquid concrete Classification of matter Metals Metalloids Non-metals Inorganic compounds Organic compounds

3. D efinition: Atoms are the basic building blocks of element and matter Atoms are indivisible particles, which cannot be created or destroyed in a chemical reaction Atoms have a nucleus ( కేంద్రకం ) : small, heavy part of the atom. An electron cloud: large light weight part of the atom An atom itself is made up of three tiny kinds of particles called subatomic particles : protons, neutrons and electrons. 3 Atom

4. Element 4 Definition: An element is a substance that is made entirely from one type of atom.

5. 5 Definition: A molecule formed when two or more atoms of the same or different types of elements combine in a fixed ratio. Molecules are of three types – monoatomic, diatomic and polyatomic molecules What are molecules? Types of molecules Atomicity : the number of atoms contained in a molecule of a substance (element or compound) is called its atomicity

6. A compound is a molecule that contains at least two different elements. Compounds contain more than one type of atom! Compounds are divided into two types Organic compounds In-organic compounds Examples of organic compounds: A compound with carbon atoms Examples of Inorganic C ompounds: A compound with no carbon atoms. All compounds are molecules but not all molecules are compounds. 6 compound

7. An ion is an atom or group of atoms with a positive or negative charge!! A particle with a neutral charge has the same number of protons and electrons. An ion does not have the same number of electrons and protons. Examples of ions: He + - A helium atom that is missing one electron. The atom has one more proton than electron, and must have a positive charge. CO 3 2- - Carbonate has two more electrons than protons 7 IONS Neutral Atom Cation (+) Anion (-) Loss of electron(s) Gain of electron(s)

8. 1Q:What is the molecular formula of hydrogen? A: H2 (H-H) 2Q: How many number of atoms present in a water molecule (H2O)? A: Total 3 atoms present in water molecule, in this 2-hydrogen atoms, 1- Oxygen atom 3Q: what is the atomic number of sodium element? A: The atomic number of sodium is -11 4Q: what is the atomicity of K2Cr2O7? A: 11 5Q: what is the chemical symbol of Cadmium? A; Cd 8 worksheet