What statement about atoms did Dalton propose?

Answer 1

John Dalton (1766 to 1844) of Manchester, as part of a life-long series of weather observations and research on gases, speculated upon the nature and constitution of the atmosphere. Issac Newton had describe an elastic fluid composed of small particles or atoms repelled by an inverse square force. It occured to Dalton to contemplate the effect of the difference of size of the particles in such a fluid under different pressures and temperatures. He tried to determine the relative sizes and weights of atoms from the numbers of atoms in a given volume. This led to consideration of combinations of gases and the numbers of atoms in such combinations. In 1801 Dalton applied the atomic concept to account for a mixture of gases exerting a pressure equal to the sum of the partial pressures. (I.e., each gas exerts its own pressure independent of other gases.) In 1803 he announced that the amount of gas dissolved in water from a mixture of gases is proportional to the partial pressure of that gas. In studying two gases made of only carbon and hydrogen, olefiant gas and carburetted hydrogen, Dalton found the latter had exactly twice as much hydrogen in relation to carbon. After applying the procedure to carbonic oxide, ammonia, and water, he published in 1808 New System of Chemical Philosophy describing how the Atomic Theory could account for chemical compositions. Dalton's Atomic Theory * Substances are composed of indivible particles called atoms. * Each element consists of a characteristic kind of identical atom. Thus there are as many kinds of atoms as elements. Atoms of a particular element are perfectly alike. * Atoms are unchangeable. * When elements combine to form a compound, the smallest portion of the compound is a group containing a definite number of atoms of each element. * In chemical reactions, atoms are never created nor destroyed, but only rearranged. Dalton listed the atomic weights of each element relative to the lightest element, hydrogen, being set equal to 1. In determining relative weights, Dalton relied on the results of quantitative analysis of compounds, and the assumed formulas for the compounds. Dalton presumed the simplest of formulas: thus water was composed of one atom hydrogen to one atom of oxygen.

Answer 2

Postulates of Dalton's Atomic Theory:

1. Atoms are made up of small indivisible particles called atoms.
2. Atoms can neither be created, nor be destroyed.
3. Atoms of same elements are similar in all respects, and atoms of different elements are different in all respects.
4. Atoms combine together in simple whole number ratios, forming molecules.

Of all these postulates, only the last one is correct.

Answer 3

You can search the internet for a full list of statements, however the most important where that:

Elements consist of atoms, which cannot be broken down any further.

The structure of the atom is called the 'billiard ball model' since it is solid and unbreakable.

Molecules consist of atoms joined together in simple, definite proportions.