class9
atoms and molecules
1.what is atom
2.what is molecules
3.low of chemical combination
4.postulates of Dalton theory
5. if anybody has this chapter note please send me
Answers
Answer:
1) the smallest particle of a chemical element that can exist.
2)a group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.
3)The law states that, 'Mass can neither be created nor destroyed in a chemical reaction. ' .According to this law, whenever matter undergoes a chemical change or physical change in an enclosed system, the total mass of reacting matter (reactants) is exactly equal to the total mass of the products of the reaction.
4)All matter consists of indivisible particles called atoms. Atoms of the same element are similar in shape and mass, but differ from the atoms of other elements. Atoms cannot be created or destroyed. Atoms of different elements may combine with each other in a fixed, simple, whole number ratios to form compound atoms.
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Explanation:
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Answer:
1. An atom is the smallest unit of ordinary matter that forms a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are extremely small, typically around 100 picometers across.
2. Molecule, a group of two or more atoms that form the smallest identifiable unit into which a pure substance can be divided and still retain the composition and chemical properties of that substance.
3. The combination of elements to give compounds. There are three laws of chemical combination.
(1) The law of constant composition states that the proportions of the elements in a compound are always the same, no matter how the compound is made. It is also called the law of constant proportions or definite proportions.
(2) The law of multiple proportions states that when two elements A and B combine to form more than one compound, then the masses of B that combine with a fixed mass of A are in simple ratio to one another. For example, carbon forms two oxides. In one, 12 grams of carbon is combined with 16 grams of oxygen (CO); in the other 12 g of carbon is combined with 32 grams of oxygen (CO2). The oxygen masses combining with a fixed mass of carbon are in the ratio 16:32, i.e. 1:2.
(3) The law of equivalent proportions states that if two elements A and B each form a compound with a third element C, then a compound of A and B will contain A and B in the relative proportions in which they react with C
4. All matter consists of indivisible particles called atoms. Atoms of the same element are similar in shape and mass, but differ from the atoms of other elements. Atoms cannot be created or destroyed. Atoms of different elements may combine with each other in a fixed, simple, whole number ratios to form compound atoms.
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