Tag: history of atomic model

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Multiple choice chemistry atoms, molecules and radicals history of atomic model atomic theory of dalton daltons atomic theory

______ are the smallest unit of matter that can take part in a chemical reaction.

  1. Molecules

  2. Compounds

  3. Atoms

  4. Electrons
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Dalton's atomic theory states that atoms are the smallest unit of matter that can participate in a chemical reaction. Chemical reactions involve the combination, separation, or rearrangement of atoms, but atoms are neither created, destroyed, divided into parts, or converted into atoms of any other kind.

Multiple choice chemistry atoms, molecules and radicals history of atomic model atomic theory of dalton daltons atomic theory

Dalton's theory of same element have same mass and properties was proved wrong with the invention of:

  1. molecules

  2. isotopes

  3. neutrons

  4. compounds
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to Dalton Atomic Theory, atoms of an element are identical in mass, size and many other chemicals or physical properties. 


But, practically we observe that atoms of several elements differ in their densities and masses. 

These atoms with the different masses are known as isotopes. For example, Chlorine (Cl) has 2 isotopes with the mass numbers of 35 and 37.

Hence, the correct option is $\text{B}$

Multiple choice chemistry atoms, molecules and radicals history of atomic model atomic theory of dalton daltons atomic theory

Various theories were put forth to study the nature of atom. The main postulates of Dalton's atomic theory are :

  1. all matter are composed of atoms

  2. all matters are composed of molecules

  3. all atoms of an element are identical.

  4. the atoms of different elements vary in size and mass.
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

It was John Dalton who firstly developed a theory on the structure of matter, later on which is known as Dalton's atomic theory.


DALTON'S ATOMIC THEORY :

1. Matter is made up of very small undivisible particle called atoms.
2. All the atoms of a given element is identical in all respect i.e. mass, shape, size, etc.
3. Atoms cannot be created nor destroyed by any chemical process.
4. Atoms of different elements are different in nature.

Multiple choice chemistry atoms, molecules and radicals history of atomic model atomic theory of dalton daltons atomic theory

Dalton suggested that atoms were indestructible and unchangeable to explain:

  1. why mass is conserved in chemical reactions.

  2. why elements combine in fixed weight ratios to form compounds.

  3. why elements are characterized by the mass of their atoms.

  4. why compounds combine in fixed weight ratios in chemical reactions.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Atoms cannot be subdivided, created or destroyed into smaller particles when they are combined,separated or rearranged in chemical reactions. The whole matter remains conserved in the form of reactants changing to products.

Multiple choice chemistry atoms, molecules and radicals history of atomic model atomic theory of dalton daltons atomic theory

Which of the following is not a postulate of Dalton's atomic theory? 

  1. Different elements have atoms of different masses.

  2. Atoms combine in simple whole number ratios to form compounds..

  3. Atoms are not created or destroyed in chemical change.

  4. Atoms of a single element can have different masses.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Postulates of Dalton's atomic theory:

  • All matter consists of indivisible particles called atoms.
  • Atoms of the same elements 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.
  • The atom is the smallest unit of matter that can take part in a chemical reaction.